Triggering the Channel-Sulfur Sites in 1T'-ReS 2 Cocatalyst toward Splendid Photocatalytic Hydrogen Generation.

Electron density manipulation of active sites in cocatalysts is of great essential to realize the optimal hydrogen adsorption/desorption behavior for constructing high-efficient H 2 -evolution photocatalyst. Herein, a strategy about weakening metal-metal bond strength to directionally optimize the electron density of channel-sulfur(S) sites in 1T' Re 1- x Mo x S 2 cocatalyst is clarified to improve their hydrogen adsorption strength (S─H bond) for rapid H 2 -production reaction. In this case, the ultrathin Re 1- x Mo x S 2 nanosheet is in situ anchored on the TiO 2 surface to form Re 1- x Mo x S 2 /TiO 2 photocatalyst by a facial molten salt method. Remarkably, numerous visual H 2 bubbles are constantly generated on the optimal Re 0.92 Mo 0.08 S 2 /TiO 2 sample with a 10.56 mmol g -1  h -1 rate (apparent quantum efficiency is about 50.6%), which is 2.6 times higher than that of traditional ReS 2 /TiO 2 sample. Density functional theory and in situ/ex situ X-ray photoelectron spectroscopy results collectively demonstrate that the weakened Re─Re bond strength via Mo introduction can induce the formation of unique electron-deficient channel-S sites with suitable electron density, which yield thermoneutral S─H bonds to realize superior interfacial H 2 -generation performance. This work provides fundamental guidance on purposely optimizing the electronic state of active sites by manipulating the intrinsic bonding structure, which opens an avenue for designing efficacious photocatalytic materials.