Hydrogen-Etched Bifunctional Sulfur-Defect-Rich ReS₂ /CC Electrocatalyst for Highly Efficient HER and OER

The design on synthesizing a sturdy, low-cost, clean, and sustainable electrocatalyst, as well as achieving high performance with low overpotential and good durability toward water splitting, is fairly vital in environmental and energy-related subject. Herein, for the first time the growth of sulfur (S) defect engineered self-supporting array electrode composed of metallic Re and ReS₂ nanosheets on carbon cloth (referred as Re/ReS₂ /CC) via a facile hydrothermal method and the following thermal treatment with H₂ /N₂ flow is reported. It is expected that, for example, the as-prepared Re/ReS₂ -7H/CC for the electrocatalytic hydrogen evolution reaction (HER) under acidic medium affords a quite low overpotential of 42 mV to achieve a current density of 10 mA cm^-2 and a very small Tafel slope of 36 mV decade^-1 , which are comparable to some of the promising HER catalysts. Furthermore, in the two-electrode system, a small cell voltage of 1.30 V is recorded under alkaline condition. Characterizations and density functional theory results expound that the introduced S defects in Re/ReS₂ -7H/CC can offer abundant active sites to advantageously capture electron, enhance the electron transport capacity, and weaken the adsorption free energy of H* at the active sites, being responsible for its superior electrocatalytic performance.