Identification of few-layer ReS2 as photo-electro integrated catalyst for hydrogen evolution

Efficient water splitting via photo-electrocatalytic (PEC) systems holds great promise for producing hydrogen fuel in future energy devices. The artificial integration of photosensitive semiconductors and co-catalysts into effective PEC electrodes is becoming significantly challenging. Here, few-layer ReS2 nanosheets (NSs) were found to have both favorable solar light harvesting and proton reducing kinetics based on the assessments for electronic band structure and Gibbs free energy (Delta G(H*)) of hydrogen adsorption. Furthermore, the naturally coupling between optical and catalytic functions was demonstrated using ReS2 NSs grown on conductive carbon fiber clothes (CFC) as a hydrogen evolution reaction (HER) cathode, where the simulated 1 sun irradiation (100mWcm(-2)) could significantly improve the catalytic activity along with anodic shifts of ca. 37 mV in onset potential and ca. 39 mV in over potential, and near 3-fold increase in exchange current density. The comparative analyses on Tafel, turnover and active sites revealed that the light-improved HER performance was due to the photo-generated hot electron injection into edge active sites. This work identifies ReS2 as a naturally PEC function-coupling material, opening a prospect of utilizing light-activated catalysts or co-catalysts to integrate catalysis with solar energy in PEC systems.