Theoretical Study of Dehydrogenation Reaction Mechanism on Cu10，Au10，Au8Cu2 or Cu1-Au8Cu2/TiO2 Surfaces

Comprehensive analysis of the connection between surface metal species and the mechanism of hydrogen (H2) generation on TiO2 provides important new information for the development of more effective catalysts for H2 production. We have systematically investigated the mechanism of catalytic H2 generation on the Cu10/TiO2, Au10/TiO2, Au8Cu2/TiO2 and Cu1/Au8Cu2/TiO2 surfaces using density functional theory (DFT). Our results demonstrate an O-Hδ+···Hδ−-M type transition state for H2 production, and the Au8Cu2 (0.54 eV) bimetallic cluster catalyst exhibits more activity in comparison to the Cu10 (0.63 eV) and Au10 (0.88 eV) cluster catalysts on the TiO2 surface. On the Cu1/Au8Cu2/TiO2 surface, we found that Au8Cu2 clusters acts as electron donor, while Cu single atom acts as an electron acceptor. Therefore, the Au8Cu2 bimetallic catalyst has a low energy barrier (0.58 eV) in the reductive reaction of H2 production in water, but Cu single atom as the catalytic center has a higher energy barrier (1.49 eV). This implies that bimetallic catalysts may be able to catalyze the water dehydrogenation reaction more successfully, which would be important knowledge for comprehending and refining the photocatalytic H2 generation process.