Boosting hydrogen evolution over Ni6(SCH2Ph)12 nanocluster modified TiO2 via pseudo-Z-scheme interfacial charge transfer

Pseudo-Z-scheme Interfacial Charge Transfer between Semiconductor and Nanocluster for Heterogeneous Photocatalysis. Ni 6 (SCH 2 Ph) 12 nanocluster as active sites of TiO 2 for heterogeneous photocatalytic hydrogen evolution via a dynamic excitation and electron-hole recombination process without strong interaction between them. • Ni 6 (SCH 2 Ph) 12 is developed as cocatalyst of TiO 2 for photocatalytic H 2 evolution. • Strikingly enhanced H 2 evolution is achieved upon the Ni 6 /TiO 2 nanocomposite. • Efficient charge transfer between TiO 2 and Ni 6 is realized via non-bond interaction. • A pseudo-Z-scheme charge transfer route is proposed to illustrate the photocatalysis. Solar energy driven photocatalytic hydrogen (H 2 ) evolution over nanocluster modified semiconductor-based photocatalysts and understanding the charge transfer between the interface of nanocluster and semiconductor is of great importance. In this work, a benzyl thiol protected nickel nanocluster (Ni 6 (SCH 2 Ph) 12 ) is developed as co-catalyst for the photocatalytic hydrogen evolution over TiO 2 catalyst. By mildly depositing the nanocluster onto the TiO 2 surface, a thirty times enhancement of hydrogen evolution efficiency and an evolution rate of 5600 μmol g −1 cat h −1 is achieved under simulated sunlight irradiation. It is found that the presence of visible light could not simulate catalytic activity solely, however, it could be a promoter to improve the hydrogen evolution efficiency of Ni 6 /TiO 2 upon ultraviolet irradiation. The boosting photocatalytic hydrogen evolution is ascribed to the efficient electron transfer from TiO 2 to the nanocluster via a dynamic excitation and electron-hole recombination process assisted by the benzyl group of the ligands, which is evidenced by experimental characterizations and DFT calculations. A pseudo-Z-scheme charge transfer route under simulated solar light irradiation is proposed to illustrate the enhancement of heterogeneous photocatalysis.