The roles of various Ni species over SnO2 in enhancing the photocatalytic properties for hydrogen generation under visible light irradiation

Abstract

The photocatalysts containing various nickel species were successfully fabricated via loading Ni(OH)2 and/or Ni2O3 species on the surface of SnO2 nanoparticles, and their roles in the photo-absorb ability, photo-induced charge transfer and photocatalytic hydrogen evolution performances were also investigated under visible light irradiation. Pt/Ni2O3–SnO2 catalyst was not active for hydrogen evolution reaction, while the photocatalytic hydrogen evolution rates of Pt/Ni(OH)2–SnO2 and Pt/Ni(OH)2–Ni2O3–SnO2 were 0.9 and 10.8 μmol g−1 h−1, respectively. It indicated that the photocatalytic activity of Pt/Ni(OH)2–Ni2O3–SnO2 catalyst had been improved evidently in the presence of Ni2O3. The UV–vis DRS results showed that Ni(OH)2 enhanced light absorption of catalyst significantly in visible light region. The i–t curves confirmed that the co-existence of Ni(OH)2 and Ni2O3 improved significantly the photocurrent of Pt/Ni(OH)2–Ni2O3–SnO2 photo-electrode. In addition, the long term experiments revealed that Pt/Ni(OH)2–Ni2O3–SnO2 catalyst was quite stable under given conditions. A proposed reaction mechanism for hydrogen evolution was also present.