It has been of interest in seeking electrocatalysts that could exercise equally high-efficient and durable hydrogen evolution upon nonselective electrolytes in both acidic and alkaline environments. Herein, we report a facile strategy to fabricate cobalt tungsten phosphides (Co_xW_2−xP₂/C) hollow polyhedrons with tunable composition based on metal-organic frameworks (MOFs) template method. By the deliberate control of W doping, the synthesized catalyst with the composition of Co_0.9W_1.1P₂/C is found to be able to achieve a current density of 10 mA·cm⁻² at overpotentials of 35 and 54 mV in acidic and alkaline media, respectively. This combined electrochemical property stands atop the state-of-the-art electrocatalyst counterparts. To unveil the peculiar behavior of the structure, density functional theory (DFT) calculation was implemented and reveals that the surface W-doping facilitates the optimization of hydrogen absorption free energy (ΔG_H^*) as well as the thermodynamic and kinetics barriers for water dissociation, which is coupled with the hollow structure of Co-W phosphides, leading to the prominent HER catalytic performance.

The catalysis of Au thin film could be improved by fabrication of array structures in large area. In this work, nanoimprint lithography has been developed to fabricate flexible Au micro-array (MA) electrodes with ~ 100% coverage. Advanced electron microscopy characterisations have directly visualised the atomic-scale three-dimensional (3D) nanostructures with a maximum depth of 6 atomic layers. In-situ observation unveils the crystal growth in the form of twinning. High double layer capacitance brings about large number of active sites on the Au thin film and has a logarithmic relationship with mesh grade. Electrochemistry testing shows that the Au MAs perform much better ethanol oxidation reaction than the planar sample; MAs with higher mesh grade have a greater active site utilisation ratio (ASUR), which is important to build electrochemical double layer for efficient charge transfer. Further improvement on ASUR is expected for greater electrocatalytic performance and potential application in direct ethanol fuel cell.

In this study, hierarchical copper nano-dendrites (CuNDs) are fabricated via the electrodeposition method. The electrochemical behaviors of the as-obtained hierarchical CuNDs in 0.1 M NaOH aqueous solution are subsequently studied. The CuNDs experience a non-equilibrium oxidation process when subjected to cyclic voltammetry (CV) measurements. The first oxidation peak O1 in CV is attributed to the formation of an epitaxial Cu₂O layer over the surface of the hierarchical CuNDs. However, the second oxidation peak O₂ in CV appears unusually broad across a wide potential range. In this region, the reaction process starts with the nucleation and growth of Cu(OH)₂ nanoneedles, followed by the oxidation of Cu₂O. Upon the increase of potential, Cu₂O is gradually transformed to CuO and Cu(OH)₂, forming a dual-layer structure with high productivity of Cu(OH)₂ nanoneedles.