Enhanced photoelectrochemical performance of defect-rich ReS2 nanosheets in visible-light assisted hydrogen generation

Defect introduction is one of the most important motivations to produce highly efficient electrocatalyst in the field of water splitting. Here we report the visible-light enhanced photoelectrochemical performance derived from defect-rich ReS2 nanosheets with high activity towards hydrogen generation from water. After continuous pre-electrolysis under visible-light irradiation for about 2 h, the activated ReS2 nanosheets electrocatalyst performs highly enhanced catalytic activity, with an onset potential decreasing from 170 to 88 mV and a long stability over 10 h. It is worth noting that only a small overpotential of 116 mV is required to afford the current density of 10 mA cm(-2), which is the highest activity to date for ReS2 electrocatalysts and much better than most transition-metal dichalcogenide materials electrocatalysts. Ex-situ transmission electron microscopy (TEM) and inductively coupled plasma emission spectrometer (ICP) examinations demonstrate that the performance improvement is attributed to the defect introduction during the visible-light assisted pre-electrolysis process involving the rhenium atoms vacancies on the basal planes and the lattice fringes of ReS2. Theoretical calculations further confirm that the abundant Re atoms vacancies with lower Gibbs free energy for H adsorption activate the inert basal plane as highly active sites for hydrogen evolution.