Free-Electron Inversive Modulation to Charge Antibonding Orbital of ReS2 Cocatalyst for Efficient Photocatalytic Hydrogen Generation.

Abstract

The free electron transfer between cocatalyst and photocatalyst has a great effect on the bonding strength between the active site and adsorbed hydrogen atom (Hads), but there is still a lack of effective means to purposely manipulate the electron transfer in a beneficial direction of H adsorption/desorption activity. Herein, when ReSx cocatalyst is loaded on TiO2 surface, a spontaneous free-electron transfer from ReSx to TiO2 happens due to the smaller work function of ReSx, causing an over-strong S-Hads bond. To prevent the over-strong S-Hads bonds of ReSx in the ReSx/TiO2 , a free-electron reversal transfer strategy is developed to weaken the strong S-Hads bonds via increasing the work function of ReSx by incorporating O to produce ReOSx cocatalyst. Research results attest that a larger work function of ReOSx than that of TiO2 can induce reversal transfer of electrons from TiO2 to ReOSx to produce electron-rich S(2+δ)-, causing the increased antibonding-orbital occupancy of S-Hads in ReOSx/TiO2 . Accordingly, the stability of adsorbed H on S sites is availably decreased, thus weakening the S-Hads of ReOSx. In this case, an electron-rich S(2+δ)--mediated "capture-hybridization-conversion" mechanism is raised . Benefiting from such property, the resultant ReOSx/TiO2 photocatalyst exhibits a superior H2-evolution rate of 7168µmol h-1 g-1 .