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When a gecko moves on a ceiling it makes use of adhesion and stiction. Stiction--static friction--is experienced on microscopic and macroscopic scales and is related to adhesion and sliding friction (1). Although important for most locomotive processes, the concepts of adhesion, stiction and sliding friction are often only empirically correlated. A more detailed understanding of these concepts will, for example, help to improve the design of increasingly smaller devices such as micro- and nanoelectromechanical switches (2). Here we show how stiction and adhesion are related for a liquid drop on a hexagonal boron nitride monolayer on rhodium (3), by measuring dynamic contact angles in two distinct states of the solid-liquid interface: a corrugated state in the absence of hydrogen intercalation and an intercalation-induced flat state. Stiction and adhesion can be reversibly switched by applying different electrochemical potentials to the sample, causing atomic hydrogen to be intercalated or not. We ascribe the change in adhesion to a change in lateral electric field of in-plane two-nanometre dipole rings (4), because it cannot be explained by the change in surface roughness known from the Wenzel model (5). Although the change in adhesion can be calculated for the system we study (6), it is not yet possible to determine the stiction at such a solid-liquid interface using ab initio methods. The inorganic hybrid of hexagonal boron nitride and rhodium is very stable and represents a new class of switchable surfaces with the potential for application in the study of adhesion, friction and lubrication., Every object at rest sticks with some adhesion to its substrate. If this object is moved, then a force must act on it. This force has to overcome the stiction [...]

An electrochemical STM setup was employed to study the electron transport characteristics in redox molecule-modified tunneling junctions Au(111)/6-thiohexanoylferrocene (Fc6)/solution gap/Au STM tip in the absence and in the presence of gold nanoclusters. The results demonstrated the power of the electrochemical approach in molecular electronics and offered a new perspective toward two-state and multistate electronic switching in condensed media at room temperature.

Study is conducted to show that individual nanoparticles can be operated as multistate switches in condensed media at room temperature, displaying distinct peak features in the tunneling current. The tunneling conductance increases with particle charge, suggests that solvent reorganization and dielectric saturation become increasingly important.

An efficient strategy for the specific immobilization of fully functional proteins onto the surface of nanoparticles is described. The absence of nonspecific protein adsorption and the specificity of the binding site are verified using several analogues of the enzymes without the histidine tag.

[Display omitted] • Two strategies for covalent attachment of MOFs to graphene are proposed. • High density of COOH groups on graphene leads to 'desert rose' MOF growth. • The 'desert rose' NiCo MOF/graphene composite is superior as OER electrocatalyst. Highly efficient and stable earth-abundant metal electrocatalysts are of great significance for improving water splitting systems and rechargeable metal–air batteries, in which the oxygen evolution reaction (OER) plays a central part. Among other strategies, anchoring metal–organic frameworks (MOFs) onto conductive materials has proven fruitful towards enhancing their OER performance. Here we explore two strategies for covalent functionalization of graphene flakes as templates for in situ growth of a bimetallic MOF (NiCo-H 2 bpydc) that is formed using 2,2′-bipyridine-5,5′-dicarboxylic acid as the organic linker, and Ni2+/ Co2+ (1:1) as the metal nodes. The graphene template modified with low density functional groups preserves the original octahedral shape of 3D NiCo-H 2 bpydc, while functionalization with high density functional groups transforms the MOF octahedra into nanoflowers with 'desert rose' morphology, leading to increased accessible active sites, electric conductivity and enlarged active surface area, thus boosting the OER performance with a small overpotential (241 mV) at 10 mA cm−2 in alkaline solution. This synthetic strategy therefore presents an efficient pathway towards controlling morphology and properties of graphene supported electrocatalytic materials with excellent OER performance. [ABSTRACT FROM AUTHOR]

The adsorption and self-assembly of several thiacarbocyanine dyes on hexagonal boron nitride (hBN) was investigated by combining steady-state spectroscopy and atomic force microscopy. The adsorption isotherms indicate that at saturation the density of the cationic TDC (5,5-dichloro-3-3′-diethyl-9-ethyl-thiacarbocyanine) molecules on hBN is similar to that of TD2 (3-3′-diethyl-9-ethyl-thiacarbocyanine) molecules, while the densities of TD0 (3-3′-diethyl-thiacarbocyanine) molecules and the zwitterionic THIATS (5,5-dichloro-3-3′-disulfopropyl-9-ethyl-thiacarbocyanine) molecules are significantly higher. The intermolecular distances between neighboring adsorbed dyes, calculated from these saturation densities indicate a flat-on adsorption for TDC, TD2 and TD0 and a partial edge-on adsorption for THIATS. AFM micrographs of the adsorbed TDC, TD0 and THIATS molecules indicate that already at low dye concentrations in the solution, where only a small fraction of the hBN surface is covered, the dye molecules already form upon adsorption to hBN aggregates of at least 10 nm, separated by areas where no adsorbed dye molecules can be detected. The resolution of the micrographs was however insufficient to show details of the packing of the adsorbed molecules. For THIATS, the thickness of the adsorbed layer is compatible with an edge-on adsorption, while for TDC and TD0, the thickness of the adsorbed layer is twice the thickness expected for flat-on adsorption. The exciton interaction extracted from the steady-state spectroscopy of the adsorbed dyes is much smaller than observed for H- or J-aggregates of the same dyes in solution or adsorbed to other surfaces such as Langmuir films or silver halides. For TDC, TD2 and TD0, the values of the exciton interaction are compatible with a close packed flat-on adsorption. Hence, optimizing the interaction between the adsorbed dye and hBN rather than between the adsorbed dye molecules governs the packing of the adsorbed dye molecules. The observation of the spectral shifts attributed to the exciton interaction at low average coverage of the hBN surface indicates that the exciton interaction already occurs at low coverage of the hBN surface. This observation is in agreement with the AFM micrographs, which show clustering of the adsorbed dye molecules already at low coverages. • TDC, TD2 and TD0 on hBN have flat-on adsorption due to optimization of dye-hBN interactions. • Exciton interaction observed already at low hBN surface coverage agrees with clustering of adsorbed dyes shown by AFM. • The packing suggested by molecular mechanics simulations is compatible with the observed exciton interaction. [ABSTRACT FROM AUTHOR]