Free-Electron Inversive Modulation to Charge Antibonding Orbital of ReS 2 Cocatalyst for Efficient Photocatalytic Hydrogen Generation.

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