Understanding the electrochemistry of “water-in-salt” electrolytes: basal plane highly ordered pyrolytic graphite as a model system

The stability of water-in-salt electrolyte systems is investigated using highly concentrated solutions of KF(aq) with graphite as a model system.

Self-assembly and wetting properties of gold nanorod–CTAB molecules on HOPG

The formation of self-assembled superstructures of cetyltrimethylammonium bromide (CTAB) after drying on a nonwetting highly ordered pyrolytic graphite (HOPG) surface have been investigated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Although SEM did not reveal coverage of CTAB layers, AFM showed not only CTAB assembly, but also the dynamics of the process on the surface. The self-assembled layers of CTAB molecules on the HOPG terraces prior to nanorod deposition were shown to change the wettability of the surface, and as a result, gold nanorod deposition takes place on nonwetting HOPG terraces.

Polymer Stamp-Based Mechanical Exfoliation of Thin High-Quality Pyrolytic Graphite Sheets

This paper reports on a polymer stamp-based mechanical exfoliation method for producing thin (<1 μm) graphite sheets from a highly ordered pyrolytic graphite (HOPG) source by tailoring key exfoliation process parameters, utilizing in-plane shear oscillation during exfoliation, and controlling the thickness of a polydimethylsiloxane (PDMS) stamp. Experiments on the effect of high frequency in-plane shear oscillation and the effect of PDMS stamp thickness are designed to reduce the thickness of exfoliated layers and to minimize surface morphological variations. Results show that the exfoliated sheets consist of a range of layer thicknesses, surface areas, and surface morphological features. The exfoliated HOPG sheets are also found to be thinner, more electrically and thermally conductive, and of higher quality than commercially available pyrolytic graphite sheets.

Surface-Limited Electrodeposition of Continuous Platinum Networks on Highly Ordered Pyrolytic Graphite

Continuous thin platinum nanoplatelet networks and thin films were obtained on the flat surface of highly ordered pyrolytic graphite (HOPG) by high overpotential electrodeposition. By increasing the deposition time, the morphology of the Pt deposits can be progressively tuned from isolated nanoplatelets, interconnected nanostructures, and thin large flat islands. The deposition is surface-limited and the thickness of the deposits, equivalent to 5 to 12 Pt monolayers, is not time dependent. The presence of Pt (111) facets is confirmed by High Resolution Transmission Electron Microscopy (HRTEM) and evidence for the early formation of a platinum monolayer is provided by Scanning Transmission Electron Microscopy and Energy Dispersive X-rays Spectroscopy (STEM-EDX) and X-ray Photoelectron Spectroscopy (XPS) analysis. The electroactivity towards the oxygen reduction reaction of the 2D deposits is also assessed, demonstrating their great potential in energy conversion devices where ultra-low loading of Pt via extended surfaces is a reliable strategy.

Electrochemically controlled winding and unwinding of substrate-supported carbon nanoscrolls

Carbon nanoscrolls (CNSs) formed spontaneously on the basal plane of highly ordered pyrolytic graphite (HOPG) show winding and unwinding movements when potential steps from 0 V to −0.5 V, −0.6 V and −0.9 V are applied on HOPG immersed in an aqueous electrolyte solution (0.1 M H2SO4).

Self-assembly and ring-opening metathesis polymerization of cyclic conjugated molecules on highly ordered pyrolytic graphite

We report the STM and AFM images of cyclophane trienes and their ROMP products, presenting unique surface morphologies on HOPG.