Interfaces and surfaces are where the action happens. Catalysis, molecular recognition, charge transfer, polymerization and many other critical processes take place at the boundary between one medium and another. With the need to integrate new materials into devices, and applications ranging from catalysis to sensors, medicine to self-cleaning surfaces, and displays to lasers, fundamental and applied studies of surface and interface processes and optimization are of critical importance in developing new technology to meet today's challenges. The selection of recent research articles presented below illustrates the vast potential of this field.
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To expand the utilization of cellulose beyond its traditional uses, it is necessary to modify the surface of the fibers. This paper summarizes the modification of cellulose by controlled polymerization methods such as ATRP, RAFT, ROP, and ROMP. The combination of the excellent properties of cellulose with functional polymers creates new materials of great potential in advanced material applications.
A simple and versatile procedure, based on the immersion method, is developed to fabricate chemical gradients on Si/SiO2 surfaces by using a silane self-assembly monolayer. The spontaneous motion of water droplet is demonstrated and the results are rationalized by dissipative particle dynamics simulations that shows that the intrinsic nature of the gradient affects the velocity of the motion.
A novel method to prepare nanoporous silver structures (NPSs) is introduced. Soluble starch is used as the in situ template, and an aqueous AgNO3 solution is used as the silver precursor. The porous NPS film is introduced in a plasmonic sensor using the Kretschmann configuration. The obtained device responds well to environmental reflective-index changes.
Multimodal plasmonic resonances: Silicon nanowires that contain multiple, dimensionally controlled, axially registered doped regions were synthesized and investigated by angle-dependent mid-infrared spectroscopy (see picture; P=partial pressure). The wires support mid-infrared multimodal localized surface plasmon resonances (LSPRs).
Defect engineering of conducting interfaces in oxide LaAlO3–SrTiO3(001) heterostructures by incorporation of a strontium copper oxide nanolayer strongly reduces the impurity scattering, opening the door to high carrier mobility materials. This remote cuprate layer facilitates enhanced suppression of oxygen defects by reducing the kinetic barrier for oxygen surface exchange in the hetero-interfacial film system.
A general strategy to overcome the limits of the grafting-to approach concerning the intrinsic limitation of the grafting density, connected with a simultaneous improvement of the switching behavior of a temperature-responsive polymer brush, is reported. The thermal azide–alkyne cycloaddition reaction is used to perform a chain extension of alkyne-functionalized poly(N-isopropylacrylamide) (PNiPAAm) brushes with azide-functionalized PNiPAAm molecules to increase the molecular weight of the attached chains without changing the grafting density.
Hole in one! Hole–shell microparticles (blue, see picture) with controllable structures and flexible internal surfaces have been fabricated from W/O/W emulsions. These microparticles could be used as microcontainers for the controlled capture/release of molecules, microsphere classification/separation, confined cell culture, or as microreactors for catalysis.
Bind until you bend: Ozone-adsorption-induced band bending is observed on Ti- and Fe-oxide surfaces under dry and humid conditions. X-ray photoelectron spectroscopy results indicate that O3 adsorption and decomposition proceed via a mechanism including a reversibly adsorbed precursor. These results contribute to the fundamental understanding of O3 adsorption and decomposition mechanisms on oxides of environmental and technological relevance.
Silver nanoparticles (Ag NPs) of various colors were synthesized within the mesopore structure of SBA-15 by using microwave-assisted alcohol reduction. The charge density is partially localized on the surface of these Ag NPs owing to localized surface plasmon resonance. This charge localization results in them having enhanced catalytic activity under visible light irradiation compared to Ag NPs obtained by thermal processes.
Three different delivery concepts (standard diffusion, global electrodynamic precipitation, and localized nanolens-based precipitation) and three different SERS enhancement layers (a silver film, a nanolens-based localized silver nanoparticle film, and the standard AgFON) are compared. The nanolens concept is applied to increase the SERS signal: a factor of 633, when compared to a standard mechanism of diffusion, is observed.
More than they appear on the surface: The treatment of SiO2 nanoparticles under mild conditions with two organoboron derivatives led to boron-containing monolayers with different types of surface species (see picture) through the direct formation of Si-O-B bonds. The organoboron-modified SiO2 NPs showed selective reactivity towards diols.
Poly (dimethylsiloxane) (PDMS) is used to fabricate micro-structured complementary surfaces by molding into a silicon master with micro-channel profiles patterned by photolithography. For each pair of complementary surfaces, dislocation defects are observed in the form of visible striations, and misalignment angle is found to be the key factor controlling dislocation distribution and adhesion strength. The ability to control the orientation and periodicity of dislocation patterns by changing misalignment angle makes this system eminently controllable.
Two new techniques to create chemical and structural heterogeneities within soft alginate substrates are presented and employed to engineer anisotropic cardiac and vascular smooth muscle monolayers. These micropatterned hydrogel substrates are ideally suited for building in vitro models of muscle contractility and tissue engineering applications as they recapitulate the mechanical properties of muscle microenvironment and their anisotropic structure.
A versatile approach based on nanosphere lithography is proposed to generate surface-imprinted polymers for selective protein recognition. Nanogravimetric measurements demonstrate that the protein (avidin) coating of the nanospheres generates selective recognition sites for avidin on the surface of the PEDOT/PSS film. This methodology coupled with oriented conjugation of the macromolecular template to the nanospheres offers the possibility of site-directed imprinting.
A robust, air-stable negative electron affinity diamond surface with giant secondary electron yield enhancement is introduced. Starting with oxidized diamond (100), lithium deposition and annealing induce a structural and electronic change to a negative electron affinity surface showing electron yield enhancement greater than 200.
The interplay between surface tension, viscosity, and drying time of organic semiconducting inks is taken into account to fabricate homogeneous active layers for organic light-emitting diodes (OLEDs) by gravure printing. The optimal formulation of the ink is identified when its properties allow a film leveling time shorter that the critical “freezing” time.
The different exfoliation routes of graphite to produce graphene by sonication in solvent, chemical oxidation, and electrochemical oxidation are compared. The results obtained show the trade-off between exfoliation speed and preservation of graphene quality. A key step to achieve efficient exfoliation is to couple gas production and mechanical exfoliation on a macroscale with non-covalent exfoliation and preservation of graphene properties on a molecular scale.
Nanorod arrays of functionalized poly(3,4-ethylenedioxythiophene) (PEDOT) are assembled by using an anodic alumium oxide template directly fabricated on gold-coated silicon wafers. These nanorod arrays are promising for organic electronic and biomedical applications. This approach allows a platform to understand the molecular and nanostructural effect on the surface wettability of these materials.
Two basic building blocks including nano-field-effect transistor (nano-FET) and nano-Schottky barrier diode (nano-SBD) can be constructed, indicating the great potential of β-AgVO3 nanoribbons (NRs) for their applications in nanoelectronic devices.
Solid phase epitaxy of the amorphous alloy CoFeB is used to fabricate crystalline ferromagnet/graphite interfaces, which are of great interest for carbon spintronics but hardly achievable with conventional thin film deposition techniques. The heterointerface features a strong body-centred-cubic (110) texture and is free from boron accumulation upon crystallization, favorable for obtaining a high spin polarization at the CoFe/graphite interface.
Patterned photoswitchable surfaces are prepared by employing a nitrile imine-mediated tetrazole ene cycloaddition (NITEC) photoinduced process in the presence of dipolarophiles based on photoresponsive azobenzene moieties. Trans-to-cis azobenzene isomerization of the surface allows for the spatially resolved tuning of the surface properties.
Unique near-field enhanced plasmonic-magnetic bifunctional nanotubes are fabricated and their plasmonic properties are investigated by both experimentation and theoretical modeling. By leveraging the bifunctionality, a nanotube can be precisely transported to a single living Chinese hamster ovary (CHO) cell amidst many and its membrane chemistry (lipid and protein) is revealed with surface-enhanced Raman scattering (SERS) spectroscopy.
Cross-linked polypeptide-based films are fabricated via a novel and robust method employing surface-initiated ring opening polymerization of α-amino acid N-carboxyanhydrides (NCA-ROP). The judicious combination of amine-based hyperbranched macroinitiators and benzyl ester-protected NCA derivatives promotes network formation by cross-chain terminations, which allows the formation of stable cross-linked peptide-based capsules in a one-pot system.
Microparticle manipulation: The photoisomerization of surfactants adsorbed at a gas–liquid interface drives a Marangoni flow that can be used for the trapping and manipulation of small particles. By switching the laser wavelength, a flow either into or away from the focal spot can be induced. The picture shows a microparticle trapped in the focal region by the inflow.
Gold nanoparticles are enclosed in cellular membranes derived from natural red blood cells (RBCs) by a top-down approach. The gold nanoparticles exhibit a complete membrane surface layer and biological characteristics of the source cells. The combination of inorganic gold nanoparticles with biological membranes is a compelling way to develop biomimetic gold nanostructures for future applications, such as those requiring evasion of the immune system.
Wrinkling of elastomeric coatings by an electric field is reported. The associated changes in the coating's optical properties yield switchable mirrors and windows. The field Ec needed to induce wrinkling is a factor of 4.4 lower than the theoretically predicted value, which is attributed to space-charge injection.
Direct detection of glycans on live cells using surface-enhanced Raman scattering (SERS) has been shown. A bioorthogonal Raman reporter was directly installed onto the monosaccharide analogs. Once metabolically incorporated into cell surface glycans, the Raman reporter was detected using SERS (see picture).
See beneath the surface! Surface analysis of biologically relevant composites leads to an improved understanding of the chemistry of nanocomposite constituents and the interactions between them (see picture).
The interaction of surfaces with biological species is largely controlled through the initial adsorption of proteins. Surface-attached hydrogel coatings can suppress protein adsorption and, subsequently, cell or blood platelet adhesion. The strong swelling of theses coatings excludes proteins either via size exclusion and/or via entropic shielding.
A patterned surface is fabricated based on controlled surface-initiated polymerization of monomer and degradation of the obtained polymer at the UV-exposed domains on the polymer surface with UV irradiation. Switching on and off of platelet adhesion on the polymer surface is realized with a precision down to single cell level. The dysfunctional platelets can be quantitatively detected based on the adhesive pattern.
The influence of varying the length of the spacer, attached to polymer nanoparticles, on the formation of a protein corona and cellular uptake are studied. Although the composition of the protein corona is not affected by different spacer lengths, an influence on cellular uptake can be identified.
A weak but productive donor: Mechanistic and kinetic insights into light-driven biphasic hydrogen evolution in the presence of the weak electron donor decamethylosmocene , which on white-light illumination produces an excited-state species that can reduce organically solubilized protons (see picture), are obtained by gas chromatographic, cyclic voltammetric, and UV/Vis and 1H NMR spectroscopic analysis.
Die another DNA: The decompaction of the DNA/hexadecyltrimethylammonium bromide (CTAB) complex is strongly influenced by the concentration of β-cyclodextrin (CD) and by the reaction temperature, owing to a subtle balance between the hydration of the complex and the lower compressibility of the native structures. Moreover, the formation of self-assembled layers of β-CD/CTAB complexes on glass or mica surfaces facilitates the immobilization of DNA, either in its coil or globule conformations (see picture).
Facile “graft-to” cycloaddition-mediated polymer functionalization of hydrothermal carbonization (HTC)-derived materials is carried out by use of a dienophile-functionalized polymer. Masked maleimide terminated poly(ethylene glycol) (PEG) is used as a model dienophile containing polymer to graft onto the surface of the HTC material. Analysis of PEGylated carbons (Fourier transform infrared, elemental analysis, X-ray photoelectron spectroscopy, and dispersion studies) all indicate the successful surface modification.
Hybridization between complementary single-stranded DNA (ssDNA) molecules loosely adsorbed on a mica surface is achieved by fine-tuning the composition of the hybridization buffer. The detection of single-molecule DNA hybridization events is performed by measuring the contour length of DNA in atomic force microscopy images.
Emulsion inversion, from water-in-oil (w/o) to oil-in-water (o/w), was accomplished by employing tetrahydropyran-containing ligands that undergo facile deprotection, converting the nanoparticles from hydrophobic to hydrophilic. These ligand-tailored nanoparticles were used to prepare w/o emulsions that were disrupted, and inverted, to o/w systems simply by lowering the solution pH. The inversion process could be triggered by light using a photoacid generator.
In situ homeotropic alignment is achieved by photochromic trans- to cis-isomerization of an azo-dye doped in a nematic host. The augmented dipole moment of the cis-isomer formed under UV-irradiation expedites molecular assembly into crystalline aggregates. Subsequent deposition of the aggregates creates a roughened surface and induces an anchoring transition from the initial planar to a homeotropic alignment of the LCs.
Matrix-assisted catalytic printing (MACP) is developed as a low-cost and versatile printing method for the fabrication of multiscale metal conductors on a wide variety of plastic, elastomeric, and textile substrates. Highly conductive Cu interconnects (2.0 × 108 S/m) fabricated by MACP at room temperature display excellent flexibility, foldability, and stretchability.
Performance by an oxidant in a leading role: In the electroless etching of silicon to form nanocrystalline porous-silicon thin films, the oxidant extracts one electron from the silicon valence band to initiate etching and then a second from the conduction band to suppress H2 formation. This discovery overturns the conventional wisdom regarding the role of the oxidant in stain etching, the stoichiometry of which was derived from the UV/Vis spectra shown.
Broadband visible-light harvesting over TiO2 is achieved by introducing gold nanorods (Au NRs) as antennas based on localized surface plasmon resonance. Furthermore, surfactant removal is achieved by an HClO4 oxidative method. Not only transversal but also longitudinal plasma of Au NRs can induce photooxidation of 2-propanol, which extends the light harvesting to the near-infrared region. Scale bar: 10 nm.
Surface modification for protein resistance: Oligo(ethylene glycol) aryl diazonium derivatives electrochemically deposited on carbon and gold surfaces reduce non-specific protein adsorption (see picture). The influence of ligand length, distal end group, and ligand packing density on protein resistance is investigated. This approach could be used to produce stable antifouling layers for electrochemical biosensors.
An experimental model is introduced for the induction of endothelial cell (EC) tubulogenesis after 24 h of incubation on micropatterned polymer surfaces. Pericytes or mesenchymal stem cells are added separately to this system to evaluate their effect on tubular stabilization. In the absence of additional cells, the tubular structures are lost after 36 h. Addition of only pericytes, however, stabilizes the EC vasculogenic tubes.
Developments in instrumentation for “high-speed AFM” (HSAFM) have been ongoing since the 1990s, and now nanometer resolution imaging and lithography at video rate is readily achievable. This review provides a summary of different approaches to and advances in the development of high-speed AFMs, highlights important discoveries made with new instruments, and discusses new possibilities for HSAFM in materials science.
Extremely high light out-coupling efficiency from a transparent organic light-emitting diode integrated with microstructures on both sides of the device is reported. The metal free device offers dramatically reduced surface plasmonic and intrinsic absorption losses. Moreover, high refractive index micro patterns with optimal light extraction condition are fabricated based on the well matched analysis of optical simulations.
Self-assembly of ZnO porous nanosheets with novel parallelogram morphology and high specific surface area is achieved by a one-pot alkalization reaction. The growth mechanism relies on the dual roles of the precursor: providing the building blocks and the assembling template concurrently. This porous structure with active surface defects serves as a high-performance semiconductor substrate for surface-enhanced Raman scattering (SERS).
The interfacial strength between individual double-walled carbon nanotubes and poly(methyl methacrylate) is characterized using an in situ nanomechanical single-tube pull-out testing scheme inside a high-resolution electron microscope. These measurements reveal the shear lag effect on the nanotube–polymer interface and demonstrate that the effective interfacial load transfer occurs only within a certain embedded length.
Direct imprinting of metal films by silicon molds without the need of resists or any intermediate layers is demonstrated using pressures of <4 MPa and temperatures of 25–150 °C. Three-dimensional metal structures with smooth and vertical sidewalls, down to sub-10 nm resolution, are generated in silver and gold films. Large-scale vivid images through extraordinary optical transmission and strong surface-enhanced Raman scattering substrates are realized quickly, repeatedly, and at a low-cost.
So simple: The in situ synthesis of an aryldiazonium salt and an azo-aryldiazonium salt by azo coupling from sulfanilic acid and aniline is reported. Formation of a mixed organic layer is monitored by cyclic voltammetry and atomic force microscopy. A compact mixed layer is obtained with a global roughness of 0.4 nm and 10–15 % vertical extension in the range 1.5–6 nm.
The strong coupling of porphyrin J-aggregates to plasmonic nanostructures of different symmetry is investigated. The nanostructures of higher symmetry show the strongest interaction with the molecular layer. At high coupling strengths a new, weakly dispersive mode appears. These findings point to new ways for optimizing strong coupling and thereby realize its full potential for molecular and material science.
Stand up straight! Vertically oriented α-Fe2O3 nanorod arrays are synthesized under hydrothermal conditions over a large area, as an active platform for surface-enhanced resonance Raman scattering (SERRS) and surface-enhanced fluorescence (SEF, see picture; LB=Langmuir–Blodgett layer of probe molecule). The morphology of the arrays is preserved after the surface is covered with a 6 nm Ag layer deposited by physical vapor deposition (PVD).
Forming micelles: The first in situ AFM study of Gibbs films of semifluorinated alkanes at liquid crystal/air interfaces is presented. The Gibbs films self-organize in a hexagonal close packing of surface micelles with shapes and lateral dimensions that are similar to micelles forming on aqueous and solid surfaces. It is concluded that he formation of surfaces micelles and their self-organization in large-area dense hexagonal arrays are intrinsic properties of semifluorinated alkane molecules.
Surface factors: The adsorption properties of water molecules on an MgSO4(100) surface are studied by using density functional theory (see picture). The configurations of water molecules adsorbed on atoms of the second and third atomic layers of MgSO4(100) are quite stable. In addition, water molecules preferentially adsorb onto a defective surface.
Self-organized graphene nanosheets with corrugated, ordered tip structures ae fabricated by a straightforward self-assembly method. The size, uniformity of the arrays, and alignment of tips are successfully controlled by the viscosity of the graphene oxide/octadecylamine solution. The vertically aligned tip structures of graphene thin films fabricated on polymeric substrate show excellent field emission characteristics upon bending.
Modern-day wonders of the world: Nanostructured films of plasmonic pyramid arrays (see picture) were prepared by the simple stamping of preformed homogeneous nanocolloids. These materials show very high efficiency as optical enhancers and can be exploited for the design of quantitative, cheap, portable, and ultrasensitive optical sensors with excellent reversibility.
Prolonged periodical variations of the surface density of a film of phospholipids adsorbed on the surface of an air bubble and in contact with a dispersion of phospholipid vesicles (orange) lead to accelerated phospholipid adsorption and lowering of the interfacial tension. The phenomenon is assigned to a coupling between the periodical variation of the surface density of the phospholipid at the interface and its dilute-to-condensed (LE-to-LC) phase transition.
Surface pyroelectricity: Centrosymmetric crystals of α-glycine display an anomalous quadrupole-like pyroelectric current. This observation implies the formation of water–glycine hybrid polar layers at the (010) faces of the α-glycine crystals (see picture).
There's the rub: Friction of single polymers on solid bodies in a liquid environment was investigated. Apart from expected mechanisms, such as slip and stick, a third nanoscale friction mechanism exists that is independent of normal force, velocity, and adsorbed polymer length. A model is proposed for this mechanism that is based on measurements with various polymers on topographically and chemically nanostructured surfaces.
Add an O: A new strategy for preparing solution-processed organic thin-film transistors (OTFTs) is based on enhancing the surface energy of self-assembled monolayers (SAMs) by inserting polar oxygen atoms into the long alkyl chain of phosphonic acids. SAMs of these phosphonic acids on a high-k metal oxide layer lead to solution-processed n-channel OTFTs with average field effect mobilities of up to 2.5 cm2 V−1 s−1 and low operational voltages.
A highly ordered hierarchical periodic structure with large area is fabricated to support surface plasmon (SP) and surface-enhanced Raman scattering (SERS). This novel metallic submicro-nano structure exhibits a complex honeycomb-like geometry, which is confirmed in experiments to support both PSPs and LSPs. Multiple modes of SPs are expected to have co-enhanced Raman scattering, heralding the development of more sophisticated hybrid surface plasmonic nanodevices.
Manipulating droplets on an open surface promises an easier, more flexible, and more scalable platform of liquid control, than does microchannel-based fluidics. In this report, a surface-energy-trap-enabled magnetic droplet handling platform is introduced that is capable of comprehensive droplet manipulations, including droplet dispensing, transport, fusion, and particle extraction.
Tell me how: The mechanism of hydrogen recombination on a Pd(111) single crystal and well-defined Pd nanoparticles is studied using pulsed multi-molecular beam techniques and the H2/D2 isotope exchange reaction. It is found that various kinetic models are required to account for the observed phenomena.
Direct growth of a single to a few layers of graphene on a germanium nanowire (Gr/Ge NW; see picture) was achieved by a metal-catalyst-free chemical vapor deposition (CVD) process. The Gr/Ge NW was used as anode in a lithium ion battery. This material has a specific capacity of 1059 mA h g−1 at 4.0 C, a long cycle life over 200 cycles, and a high capacity retention of 90 %.
Sir, yes sir! Chiral induction and amplification in surface-confined supramolecular monolayers are investigated at the liquid–solid interface. Scanning tunneling microscopy proves that achiral molecules can self-assemble into globally chiral patterns through induction by chiral solvents or by a novel chiral amplification method.
A sub-monolayer distribution of isolated molecular Fe14(bta)6 nanomagnets is deposited intact on a Au(111) surface and investigated by X-ray magnetic circular dichroism spectroscopy. The entropy variation with respect to the applied magnetic field is extracted from the magnetization curves and evidences high magnetocaloric values at the single molecule level.
A novel approach to manipulating multiple optical signals at subwavelength scale is proposed in dendritic organic/metal nanowire heterostructures. The heterostructures are prepared by embedding Ag nanowires in fac-tris(2-phenylpyridine) iridium microwires during the self-assembly in liquid phase. Optical signals inputted from the organic waveguide can be selectively transferred to the predetermined subwavelength output ports based on the angular dependence of the photon-plasmon coupling.
Real-time surface microscopy and in situ spectroscopy can provide unique insight into graphene and other 2D materials on metal substrates. The power of in situ microscopy in realizing and probing important functionalities in 2D materials is illustrated by reviewing recent progress in understanding scalable graphene growth on metals, processing by selective chemistry at the graphene/metal interface, and important properties such as band structure, work function, etc.
Self-assembled plasmonic nanoring cavity arrays are formed alongside the curvature of highly packed metallic nanosphere gratings. The sub-10-nm gap size is precisely tuned via atomic layer deposition and highly ordered arrays are produced over a cm-sized area. The resulting hybrid nanostructure boosts coupling efficiency of light into plasmons, and shows an improved SERS detection limit. These substrates are used for SERS detection of the biological analyte, adenine, followed by concurrent localized surface plasmon resonance sensing.
Hollow composite microcapsules are prepared by the assembly of pre-formed nanocrystals of metal-organic frameworks (MOFs) around emulsion droplets, followed by interfacial polymerisation of the interior. The micropores of the MOF crystals embedded within a semipermeable hierarchically structured polymeric membrane are an effective combination for the retention of encapsulated dye molecules. Release can be triggered however by acid dissolution of the MOF component.
DNA nanotrain: Anchoring of preformed fluorescent DNA nanodevices (NDs; see picture) and in situ self-assembly of fluorescent DNA NDs on target living cell surfaces are reported. The in situ self-assembly of the nanodevice was further shown on surfaces of living cells in cell mixtures. These DNA NDs exhibited fluorescence emission and underwent fluorescence resonance energy transfer (FRET) on living cell surfaces.
The active state of a catalyst: A high-pressure scanning tunneling microscope (STM) was used to bridge the pressure gap for the Ag-catalyzed ethylene epoxidation. An active oxygen species on an Ag(111) single crystal was characterized under ultrahigh vacuum conditions. The same species was identified with STM in an ethylene/oxygen mixture (see picture). In the STM cell the formation of ethylene oxide was detected.
Due to the recent development of bottom-up and top-down approaches for material design and fabrication at the nanoscale, giant chiroptical effects have been reported from plasmonic nanostructures. These effects are exhibited both in the linear and in the nonlinear optical regimes and are sensitive to the chirality of nanostructures, the chirality of the experiments and the chirality of light itself.
A possible way to fabricate a half-metallic sandwich molecular wire on a silicon surface is proposed using first-principle calculations. The magnetic state of this molecular wire is sensitive to the electric field and can be changed between two states. The hybrid system has very promising application in emerging molecular electronic or spintronic devices.
Exposure of organic solar cells (OSCs) to light results in degradation in all OSC parameters, even in inert environments. The use of electron extraction layers (EELs) in between the organic layer and an Al layer can largely suppress contact photo-degradation and enhance OSC photo-stability. Lithium acetylacetonate, as a new EEL material, provides efficiency improvement on par with the ubiquitous LiF, but with some additional stability improvement.
Las-ing around: Quantum mechanical desorption induced by electronic transition simulations in 3D is reported to describe the recombinative desorption of H2 and D2 from Ru(0001) produced by low-intensity laser fields. The experimental trends at low laser fluences are well reproduced for the isotopic ratio and the translational and rotational energies. A single temperature is sufficient to characterize the energy distributions for all degrees of freedom.
The tuning of the molecular material work-function via strong coupling with vacuum electromagnetic fields is demonstrated. Kelvin probe microscopy extracts the surface potential (SP) changes of a photochromic molecular film on plasmonic hole arrays and inside Fabry-Perot cavities. Modulating the optical cavity resonance or the photochromic film effectively tunes the work-function, suggesting a new tool for tailoring material properties.
Surface properties of functionalized nanoparticle (NPs) under different solvent conditions are modified by electron beam treatment. The specific surface layer (proximity length) of the NPs is activated, which modifies the NPs' light-responsiveness. For example, amine-functionalized NPs activated by the electron beam, exhibit UV-vis absorbance at the lower wavelength than that those without electron beam treatment. This NP activation technology is advantageous for effective light energy use.
Where oxide and metals meet: The activation of an efficient associative mechanistic pathway for the water–gas shift reaction by an oxide–metal interface leads to an increase in the catalytic activity of nanoparticles of ceria deposited on Cu(111) or Au(111) by more than an order of magnitude (see graph). In situ experiments demonstrated that a carboxy species formed at the metal–oxide interface is the critical intermediate in the reaction.
Classical diffusion—quantum barrier: On Cu(111), pyrrole diffuses in channels, hopping between adjacent bridge sites over a barrier above hollow sites. The motion of the center of mass can be described classically; however, the activation barrier arises from the quantum character of internal vibrational modes that are largely unexcited during the motion. The unique helium spin-echo experiment is indicated by the green sphere and arrows.
A well-defined amphiphilic polypeptide, poly(glutamic acid)22-block-poly(alanine)8 (PGlu22-b-PAla8) is taken as organic additive to mediate the mineralization of CaCO3. Asymmetrical calcite particles with various shapes are obtained at the air/water interface and PGlu22-b-PAla8 acts as a bifunctional template in the mineralization process according to time-dependent observations.
Resorbable poly(trimethylene carbonate-co-ε-caprolactone) networks with a wide composition range are prepared by γ-irradiation of the corresponding linear polymers. It is shown that the network composition has a large effect on the mechanical properties as well as on the erosion behavior. These biocompatible networks are suitable for a variety of applications in medicine such as in drug delivery and tissue engineering.
Flavin away: Dodecin binds oxidized flavins, whereas reduction of the bound flavin induces dissociation of the holoprotein into apododecin and free flavins. The stepwise reconstitution of dodecin on flavin-terminated ds-DNA monolayers showed that although electrochemical flavin reduction (i.e. electron transfer through DNA) was not possible, apododecin (gray circles) could be released by chemical reduction (see scheme).
Taking the bait: Protein-interaction arrays were generated in living cells by the interaction of bait-presenting artificial receptor constructs (bait-PARCs) with micrometer-scaled antibody surface patterns (see figure). This method was applied to simultaneously monitor the interaction kinetics of a prey protein with two distinct bait proteins in individual living cells.
A full understanding of the mechanism of the formation of a two-dimensional electron gas (2DEG) at the interface between insulating LaAlO3 (LAO) thin films and bulk SrTiO3 (STO) crystals is a prerequisite for the full exploitation of this class of materials. Here, by using a combination of advanced X-ray synchrotron-based spectroscopic and structural measurements, it is shown that a structural and electronic reconstruction of the interface occurs before the realization of the 2DEG.
Opto-chemical sensors are prepared by self-assembly of SiO/SiO2 nanomembranes into microtube structures. Dynamic molecular processes of H2O and C2H5OH are detected on the surface of sub-wavelength-thin nanomembranes. Based on the perturbation theory, quantitative information of molecule layer changes is acquired. The nanomembrane-based molecular-sensing ability constitutes a versatile platform for the detection of diverse surface phenomena in a label-free fashion.
Superhydrophobic porous surfaces with hydrophilic polymers adsorbed in pores are designed to control the coalescing behavior of microdroplets as well as their quick self-removal. The combination of chemical composition and surface structure are greatly important in the design of new materials for heat exchange, antifogging, and anti-icing.
A purely topographical method for controlling liquid spreading by using easy-to-fabricate undercut edges is reported. By periodic repetition of such edges, it is shown that multiple droplets can be patterned in well-controlled shapes, and highly anisotropic wetting can also be achieved at a large scale. Apparent contact angles close to 180° at the edge are shown, even for low surface tension liquids.
Graphene is a unique platform for surface-enhanced Raman spectroscopy (SERS). The multi-role of graphene played in SERS is overviewed, including as a Raman probe, as a substrate, as an additive, and as a building block of a flat surface for SERS. Apart from versatile improvements on SERS performance towards applications, graphene-involved SERS studies are also expected to shed light on the fundamental mechanism of the SERS effect.
A self-limiting growth process based on the interface-controlled reaction of molten boron oxide (B2O3) with ammonia (NH3) is demonstrated for the facile and lost-cost synthesis of ultrathin (20–30 nm) crystalline hexagonal boron nitride (h-BN) films over large areas. The as-grown h-BN films are of high quality, being densely continuous, uniform and smooth, and highly transparent over a broad wavelength range.
Amazing ammonia: The molecular spin state of NiII porphyrin, supported on a ferromagnetic Co surface, can be reversibly switched between spin-off (S=0) and spin-on (S=1) states upon coordination and decoordination of the gaseous ligand NH3, respectively (see picture). This finding clearly indicates the possible use of the system as a single-molecule-based magnetochemical sensor and in spintronics.
The hydroxyl functionalities in graphene oxide (GO) are subjected to Johnson−Claisen rearrangement conditions, which trades the labile CO bond for a robust CC bond. Further functionalization allows for the synthesis of highly charged, water-soluble graphene. The negatively and positively charged graphenes (zeta potentials of –75 mV and +56 mV), are successfully used to build layer-by-layer (LBL) constructs.
It is shown that the metal capping electrode in an organic photovoltaic device affects the stratification of materials in the bulk heterojunction (BHJ) and that solvent additives can inhibit stratification. It is found that some metals can donate charge to (6,6)-phenyl-C61-butyric acid methyl ester (PCBM). The enrichment and charging of PCBM at the interface with the metal increases device power conversion efficiency.
Bacterial adhesion can be controlled by applying electrical potentials to surfaces incorporating well-spaced negatively charged 11-mercaptoundecanoic acids. When combined with electrochemical surface plasmon resonance, these dynamic surfaces become powerful for monitoring and analysing the passage between reversible and non-reversible cell adhesion, opening new opportunities to advance our understanding of cell adhesion processes.
A matter of doping: Graphene nanoribbons (GNRs) were generated through an on-surface bottom-up synthesis and selectively doped at their edges by introducing nitrogen atoms in the precursor monomers. While the size of the band gap of 2.8 eV remains almost unchanged upon N substitution, a linear shift of the band structure is observed and corresponds to n-type doping (see picture; CB=conduction band and VB=valence band).
Precise estimates of properties such as surface roughness, height, electrical characteristics and surface potential are obtained from scanning probe microscopy images by means of a quantitative approach based on histogram analysis (see picture).
A single gold microshell, which was elaborately fabricated to carry numerous hot spots on its own surface, enabled the acquisition of the SERS spectra from the molecules on non-SERS active substrates such as Si/SiO2, ITO, and glass. A self-assembled monolayer of 11-mercaptoundecanols on the gold microshell offered an easy and reliable way to electrically insulate from the underlying flat Pt electrode and accomplish in situ monitoring the electrochemical reaction with minimal interference.
Reduced degradation (oxidation) of silver nanoparticles (NPs) is achieved by contacting Ag with immiscible Co NPs. The relative decay of the plasmon peak (plot) shows that pure Ag NPs (blue dashed curve) decay by 25% in ca 20 days, whereas AgCo NPs last about 10 times longer, requiring nearly five months for a similar decay (red solid curve). The TEM images for both Ag and AgCo were taken after 50 days of storage under ambient conditions.
“Photothermometer”: A PAOF system was constructed using a diode laser as the energy source, an aqueous suspension of plasmonic nanostructures as the photothermal transducer, and a glass capillary for measuring the volumetric expansion of the suspension (see picture). The suspension could be driven to move up the capillary by more than 30 mm and be used to control the operation of an electrical switch.
Large-sized, 2D single crystals of perylene are grown by both solution-cast and physical vapor transport methods. The crystals have a atomically flat parallelogram morphology and the aspect ratios of the lateral extension compared to the thickness are up to 103. The atomically flat feature leads to good interface contact, making a single-crystal field-effect transistor with higher mobility. The mobility of atomically flat crystals can be 103–104 times higher than rough crystals.
Peptide micropatterning on polymer surfaces are designed to control endothelial cell (EC) functions. ECs form tubular structures with a central lumen depending on both microgeometrical cues of peptide micropatterns and different migration modes of actin machinery on the peptide micropatterns.
A novel post etch chemical process is developed to etch III–V materials with monolayer precision in an inverse epitaxial manner. The process, which also simultaneously passivates the surface, is applied to push the limits of top-down fabrication. InP-based high-optical quality nanowire arrays with aspect ratios more than 50 and nanostructures with new topologies are demonstrated.
SiO2 thin films prepared at glancing geometries are used as templates to grow gold nanoparticles that depict optical dichroism around the azimuthal and polar axis of the films and yield unprecedented possibilities for the encryption of optical information.
An open-and-shut case: By using tailored molecules, the formation of open or close-packed supramolecular network can be achieved on a silicon-based surface. The role of molecule–molecule interactions and molecule–substrate interactions to control the geometry of organic network on semi-conductor surface is investigated.
The first direct probing of the nanomechanics of cation–π interactions in aqueous media was accomplished by using a surface forces apparatus with complementary theoretical simulations. The tetraethylammonium (TEA) ion breaks the adhesion between poly-L-tryptophan (PTrp) and poly-L-lysine (PLL) with a 100 times higher sensitivity relative to the K+ ion (PS=polystyrene, PTyr=poly-L-tyrosine, and ACh=acetylcholine).
On-surface synthesis is a promising approach for constructing covalently bound nanostructures. However, the number of reliable chemical reactions suitable for on-surface chemistry is very limited. Arylalkynes can be coupled at various surfaces in a novel 2D Glaser coupling (see picture). This approach can be used for constructing conjugated materials directly on surfaces.
A single H adatom on an anatase (001) surface can lower dramatically the dissociation barrier of the O2 molecule (see picture; O2 blue, H green). With two H adatoms, O2 is also strongly adsorbed with O=O bond cleavage, but the system energy increases after dissociation.
Bead up: A coarse-grained (CG) model for the simulation of nanoconfined water between graphene surfaces is developed (see picture). The constructed CG potentials are shown to be pore-size transferable, capable of predicting structural properties of confined water over a wide range of pore sizes. The model predicts the layering of water in contact with the surfaces and the solvation force is in complete agreement with the mixed-grained model.
Gas sensors at work: The mode of operation of metal-oxide gas sensors can be studied by simultaneous measurement of the sensor response, adsorbates, changes in the metal-oxide material, and gas-phase composition by operando Raman–FTIR spectroscopy. Depending on the gas environment and temperature, for EtOH sensing by In2O3, a correlation has been found between the sensor signal, presence of adsorbates, oxidation state of the sensor material, and intensity of surface hydroxy groups.
Creating patterns of extreme wettability on surfaces leads to new functionalities and possibilities in a wide variety of applications. We highlight novel applications of superhydrophilic-superhydrophobic patterned surfaces that are currently being explored, from miniaturized cell and chemical screening platforms to surface tension confined microchannels for separation and diagnostic devices, and give an outlook on the progress in this field.
New insights in capillary interactions between nanofilaments have led to versatile and scalable methods to build complex structures that cannot be achieved by any other processing technique. Understanding the control of this process is conducive to the development of high-performance battery and capacitor electrodes as well as photovoltaics, electrical interconnects, and other smart materials.
Catechols participate in several natural processes and functions that range from the adhesive properties of marine organisms to the storage of certain metals ions. Accordingly, many scientists worldwide have been studying and mimicking these natural systems to develop new active materials and coatings. A detailed revision of a wide variety of relevant studies in this field is discussed in this Review.
In this review, a brief introduction to surface modification using poly(N-vinylpyrrolidone) and its copolymers and their potential biomedical applications is presented. Some perspectives on future research in the areas are also discussed.
In a molecularly decorated surface, the molecular tiles are “glued” to the surface by binding constants and possibly further “glued” to each other by cooperativity factors. At odds with mosaics, these “glues” come with the tiles and cannot be removed or supplemented. Binding polynomials quantify glue amounts from experimental data and may predict molecular self-organization on surfaces that can be exploited in organic (opto-)electronics.
Dynamic surfaces: Construction and applications of dynamic surfaces on which surface properties can be modulated by an external stimulus on user demand are reviewed, with focus on self-assembled monolayers with dynamicity that stems from (bio)chemical conversions on the surface in response to stimuli such as electrical potential, light, enzymes, and pH (see picture).
Monolayer zeolite? The application of a variety of “surface-science” techniques to elucidate the surface structures and mechanisms of chemical reactions at zeolite surfaces has long been considered as almost impossible. The growth of a thin aluminosilicate film on a metal single crystal under controlled conditions results in adequate and well-defined model systems for zeolite surfaces.
In a different light: In a provocative look at nanoscience, Nobel Laureate Roald Hoffmann considers the structural and electronic perplexities of dimensionality, the consequences of bond severance in nano-object formation, the implications of simple acid-base chemistry for stabilization of nanostructures, and what lessons might be learned from surface science on structural relaxation and reconstruction.
Scratching the surface: For over 100 years the interactions of molecules at surfaces have been studied at the Fritz Haber Institute of the Max Planck Society, Berlin. Nobel Laureate Gerhard Ertl looks back at some of the key developments in this time, and the people who made them.
Bubble, bubble: Why does champagne bubble? Why does it stop bubbling? Does the vintage affect its fizz? Chemistry can answer these and other questions about the wine that is so often associated with celebrations and anniversaries.
The origin of the charge on oil/water interfaces that can be found from electrokinetic mobility measurements is a long-standing issue that has invoked different explanations. Sum frequency scattering (SFS) shows that impurities are likely not a general cause for the charge (see picture).
The effect of fatty acid impurities on the electrophoretic mobility of hexadecane in water emulsions is reinterpreted, occasioned by an error in the surface charge attributed to the fatty acids. The results are consistent with a surface charge contributed by both hydroxide ions and deprotonated fatty acids (see picture).
Pure is uncharged: Uncontaminated hydrophobic interfaces, such as PMMA-H/water interfaces, are uncharged. If the macromolecules have instead ionizable carboxylic acid endgroups, such as PMMA-COOH, a surface charge similar to the contaminated oil/water interface is obtained.
A simple and inexpensive approach is used to coat metal oxide surfaces (SBA-15) with thin films of carbon. These carbon films provide improved hydrothermal stability to oxides, such as silica and alumina, which are not otherwise stable at elevated temperatures in the presence of liquid water (see picture). Furthermore, the carbon film changes the surface chemistry of the support.
Particle characterization by asymmetrical flow field-flow fractionation (AF-FFF) and thermal field-flow fractionation (ThFFF) in aqueous solution is highly affected by the electrolyte in the carrier liquid. In this feature article, the impact of salinity and ion specificity on fractionation behavior is discussed. Forces acting in the fractionation channel and electrostatic particle–particle and particle–wall forces are highlighted.
Space, the final frontier? Microfluidic technologies for controlling liquid dispensing and handling will become central for localizing (bio)chemical reactions/functions on biological interfaces. However, microfluidic systems must then operate in the “open space”, that is, without the sealed channels and chambers commonly used (see picture). The development of such open-space microfluidic technologies is reported.
Experimental and theoretical progress on surface-catalyzed reactions of p,p'-dimercaptoazobenzene (DMAB), produced from para-aminothiophenol (PATP) and 4-nitrobenzenethiol (4NBT), assisted by local surface plasmons (LSPs) and a plasmonic waveguide is reviewed. “Hot” electrons generated by surface plasmon decay play an important role in chemical reactions. A novel method to synthesize new molecules, assisted by local LSPs or plasmon waveguides at the nanoscale, is proposed.
Interface unveiled: A new massless model for use in dynamic atomic force microscopy experiments aids in the study of solid–liquid interfaces of viscous liquids.
Faster, higher, stronger,... simply better. True to the Olympic motto: late lanthanide metallocenes polymerize vinylphosphonates extremely fast (TOF up to 125 000 h−1) and give access to high-molecular-weight polymers. The reaction proceeds in a living fashion via a rare earth metal-mediated group transfer polymerization mechanism. Surface-initiated group transfer polymerization allows fast and efficient preparation of thick and uniform polymer brushes.
A two-dimensional array of gold optical antennas integrated with a one-dimensional array of gold strips and mirrors is introduced and fabricated. The experimental results show that this design achieves average surface-enhanced Raman scattering (SERS) enhancement factors as high as 1.2 × 1010, which is more than two orders of magnitude larger than optical antennas without the gold strips and gold mirror.
The rapid development of nanomaterials as SALDI-assisting agents in SALDI-TOF-MS has greatly enhanced the capability of this analytical technique. This article describes the ingress of this technique into the field of forensic analysis.
Conventional optical tweezers, in which lasers are focused with microscope objectives, are limited in the trapping force they can exert on an object for a given laser power. In this Concept, the authors review the fundamentals of optical tweezers and describe an optical nanotweezer (see picture) that exceeds the performance limitations of conventional tweezers while avoiding thermal effects with a heat-sinking approach.
Of all shapes and sizes: Precise control over graphene synthesis is crucial for probing their fundamental physical properties and introduction into promising applications. In this Minireview, the recent progress that has led to the successful chemical synthesis of graphene with a range of different sizes and chemical compositions based on both top-down and bottom-up strategies is highlighted (see figure).
Atomic layer deposition (ALD) is a highly tunable technique for fabricating various nanostructured materials that can potentially be used in lithium-ion batteries (LIBs) as anodes, cathodes, or inorganic solid electrolytes. It is also a viable approach to coat electrode materials of LIBs for improved performance.
Increasing lattice parameters for nanoparticles of decreasing sizes have been reported for a large variety of materials. The authors summarize experimental results and examine the theoretical foundation of this seemingly anomalous behavior, revealing that negative surface stress is the decisive factor. The picture shows the local atomic strain in a hexagonal GaN nanoparticle (where the blue shades represent negative strains, or contraction, and the yellow–red ones denote positive strains, i.e., expansion).
Hybrid materials for photovoltaics: The recent development of solution-processed hybrid polymer–nanocrystal photovoltaic cells is reviewed. The tailoring of colloidal nanocrystals and conjugated polymers as well as the manipulation of polymer–nanocrystal interfaces and device architectures are highlighted. The picture shows device structure and J–V characteristics of a hybrid photovoltaic device.
Significant efforts have been made to develop functional biodegradable scaffolds for tissue regeneration that can enhance cell function and guide new tissue formation. This paper discusses the recent advancements of functionalizing synthetic biodegradable polymer scaffolds, focusing on polymer synthesis, surface modification, and cellular response on these functionalized scaffolds.
Recent developments in the area of bioinspired directional surfaces with precisely tuned physicochemical surface properties are summarized. These surfaces, characterized by asymmetric features, can transport droplets, provide directional wet and dry adhesion, and exhibit directional friction.
Forever blowing (nano)bubbles! Gas states observed at the nanometer scale include nanobubbles, micropancakes, multiple gas layers, and their coexistence (see picture). Molecular dynamic simulations showed that nanoscale gas bubbles may have a high inner density, which could be one reason why nanobubbles are stable at water/solid interfaces.
On the bubble: Surface and bulk nanobubbles (see picture) are two types of nanoscopic gaseous domain that occur in interfacial physics. The common and disparate features of both bubble types are described, and their possible stabilising mechanisms and potential applications are examined.
The incorporation of gold nanoparticles in surface plasmon resonance biosensing can be used to improve device sensitivity. A number of formats have been used in which gold nanoparticles enhance the signal for detecting a variety of biomolecules, including both label-free and labeled methods. These methods as well as device fabrication and the results of incorporation are reviewed.
Graphene oxide films were fabricated as low-cost and flexible nanogenerators to convert acoustic energy into electricity with a conversion efficiency of 12.1 % (see picture). The generated current sensitively depended on the pH value of the suspensions for graphene oxide (GO) film production.
After all, it's active: High-resolution scanning electrochemical cell microscopy (SECCM) demonstrates that electron transfer at the basal plane of highly oriented pyrolytic graphite (HOPG) is fast. This finding requires radical revision of the current textbook model for HOPG electrochemistry.
What's the charge? X-ray photoelectron spectroscopy was used to determine the charge state and dynamics of charge build-up and decay on a thin poly(methyl methacrylate) film. The film is initially negatively charged to around −2 V and becomes progressively positively charged during the course of the XPS analysis.
A detailed review of the experimental approaches followed for the structuration of magnetic nanoparticles on surfaces is presented. Special attention is given to understand the parameters that control self-assembly, including the use of biological templates. Finally, the implementation of all the knowledge previously gained is translated to the integration and implementation on sensors and devices.
The swelling behaviour of surface- tethered weak polyelectrolytes in salt solutions is studied by both ellipsometry and quartz crystal microbalance (QCM). Ellipsometry studies support the proposed solidified liquid layer (SLL) model. QCM experiments designed according to the SLL model are highly sensitive: a 0.18 nm thickness change of the SLL will lead to a 1 Hz frequency change.
In the swim: Until now, X-ray photoelectron spectroscopy (XPS) has been predominantly applied to the investigation of near-surface regions. Recent work has now brought XPS into a new domain with the direct monitoring of bulk reactions in the liquid phase. In the monitored reaction, the cation of an ionic liquid (IL) reacts with the anion of another IL (see scheme).
The first use of non-centrosymmetric Janus Au-TiO2 photocatalysts in efficient, plasmon-enhanced visible-light hydrogen generation is demonstrated. The intense localization of plasmonic near-fields close to the Au-TiO2 interface, coupled with optical transitions involving localized electronic states in amorphous TiO2 brings about enhanced optical absorption and the generation of electron-hole pairs for photocatalysis.
On the surface: The surface reconstruction of an MoVTeO complex metal oxide catalyst was observed directly by various electron microscopic techniques and the results explain the puzzling catalytic behavior.
A fragmented approach: 3-Phenyl-5-piperazino-1,2,4-thiadiazole (designated “compound 382” in the Ro5 Maybridge Fragment Library, see scheme) is demonstrated to be an effective inhibitor of human blood group glycosyltransferase B. The compound interferes with both acceptor and donor binding and also displaces the Mn2+ ion in the binding pocket.
With a little air, one can make a huge impact! Surface patterning is one of the most fundamental techniques in modern times. Recently air was employed as the separating barrier for surface patterning using superhydrophobic surfaces. This new concept has promising potential for flexible, high-throughput, and high-resolution micropatterning, and it is expected to further expand the applications of superhydrophobic surfaces.
One and all: Electron transport through a single molecule between metal electrodes is a topic of great interest in the development of nanoscale molecular electronic devices. π-Conjugated molecules have attracted attention due to their unique properties. The fabrication and electron-transport properties of the single π-conjugated molecule junction (see picture) are discussed.
Approaches to fabricate arrays of asymmetric 2D and 3D surface features, in polymers, metals, and ceramics are reviewed. These combinations of geometries and materials can impart unique anisotropy in surface properties including wetting, adhesion, thermal and/or electrical conductivity, optical activity, and capability to direct cell growth, and are of interest for applications including energy conversion, microelectronics, chemical and biological sensing, and bioengineering.
The latest developments in the fabrication of polymer nanostructures using scanning probe lithography (SPL) are highlighted, with special categorization by different material applications into polymer resists, polymeric carriers for functional materials, electronically active polymers and polymer brushes. The attributes of SPL in patterning polymer nanostructures are also summarized.
A comprehensive overview on the subject of current injection in organic thin-film transistors is given: physical principles concerning energy level (mis)alignment at interfaces, models describing charge injection, technologies for interface tuning, and techniques for characterizing devices. Finally, a survey of the most recent accomplishments in the field is given.
Not your cup of tea? “Coffee rings” of spherical colloidal particles are left behind after water droplets resting on surfaces have dried out. This controlled evaporation of colloidal solutions can be exploited to deposit material in regular patterns (see picture). It is now shown that if spherical colloids are replaced by slightly elongated ones, the coffee ring is not formed and is replaced by an even more uniform deposition.
Surface chemistry on nanodiamond has developed into a field in its own right in recent years. The large variety of possible functionalization reactions on the surface of this purportedly inert material is presented. These modifications enable the application of nanodiamond in areas such as bioimaging, composites, or quantum engineering.
In an organic field-effect transistor redox reactions at the surface of the gate dielectric involving water can lead to conversion of holes in the accumulation layer into protons. The protons diffuse into the gate dielectric and cause a shift of the threshold voltage of the transistor.
Smart stimuli-responsive polymeric systems with smart surfaces are used for engineering a biological construct embedded with cells and biomolecules/drugs. Upon response to suitable stimuli like pH in vivo, the polymer unwinds and becomes hydrophobic thereby delivering cells and biomolecules to the target organ in the human body.
The recent experimental and theoretical work on the fabrication of well-ordered mesoscopic structural surfaces over large areas is reviewed. Methods such as the Langmuir–Blodgett (LB) technique are described. Furthermore, the patterning of materials with LB transfer or other dynamic processes such as dip-coating is summarized.
Preassembling singly charged, uncharged, or water-repellent building blocks in an unconventional layer-by-layer fashion enhances the ability for advanced functionality, in particular, surface molecular imprinting, of the resulting multilayer film.
Linear alkane polymerization is achieved on the Au(110) surface with 1D constrained nanochannels, which play a key role in the selective C–H activation and C–C bond coupling.
Less is more: Basic concepts, examples and applications of organic–organic heterostructures are reviewed (see picture). Heterostructures in the monolayer regime, including nanostructuring concepts and systems involving self-assembled monolayers, as well as various other architectures, including superlattices, are discussed.
Chemical etching is widely applied to texture the surface of sputter-deposited zinc oxide for light scattering in thin-film silicon solar cells. Based on experimental findings from the literature and our own results we propose a model that explains the etching behavior of ZnO depending on the structural material properties and the etching agent (see picture).
Bottom-up fabrication methods based on self assembly of molecules are developed for solution-processed production of organic semiconductor devices. Our methods enable area selective crystallization of molecules and direct formation of organic single crystals from solution. Since these methods can be processed under ambient condition at room temperature, they are fully compatible with printable electronics technology.
A rich source: Calculated reaction and activation energies for elementary coupling reactions occurring on metal surfaces can be found by using a web application. This tool provides access to data for reactions of molecules with up to three C, N, or O atoms on a number of different transition-metal surfaces. The underlying dataset is generated from a consistent set of DFT calculations and extrapolations based on linear scaling relations.