Dual-Enhanced Doping in ReSe2 for Efficiently Photoenhanced Hydrogen Evolution Reaction.

Rhenium dichalcogenides (ReX2, X = S or Se) are catalysts that have great promise for the photoenhanced hydrogen evolution reaction (PE-HER) because of their unique physiochemical properties. However, the catalytic performance is still restricted by their low concentration of electrocatalytic activity sites and poor injection of hot electrons. Herein, dual-enhancement in ReSe2 nanosheets (NSs) with high concentration of active sites and efficient use of hot electrons is simultaneously achieved with moderate Mo doping. Contributions from exposed catalytically active sites, improved electrical conductivity, and enhanced solar spectral response are systematically investigated. Superior PE-HER catalytical performance is obtained in Re0.94Mo0.06Se2, which has more catalytically active sites and optimized band structure than other Re1- x Mo x Se2 samples. Here, it is demonstrated that only doping can reduce the overpotential (η10) from 239 to 174 mV at -10 mA cm-2 (Δ1η10 = 65 mV). Then, η10 is further improved to 137 mV under simulated AM 1.5 sun illumination (Δ2η10 = 37 mV). The total improvement (Δη10) toward PE-HER is 102 mV (Δ1η10 + Δ2η10 = 102 mV) in optimal Re0.94Mo0.06Se2. This work presents a new perspective for researching high-efficiency photoenhanced HER ReSe2-based electrocatalysts and other layered transition metal dichalcogenides.