Self-assembly of Ni2P/γ-Ga2O3 nanosheets for efficient photocatalytic water splitting hydrogen production

Abstract

The development of photocatalysts enabling stable and highly efficient water splitting hydrogen production remains an open challenge in the field of energy photocatalysis. Herein, Ni₂P/γ-Ga₂O₃ nanosheets have been reported as excellent water splitting photocatalysts. Ni₂P particles and γ-Ga₂O₃ nanosheets were synthesized by a facile hydrothermal process. The Ni₂P/γ-Ga₂O₃ samples were prepared by an electrostatic self-assembly method with Ni₂P particles and γ-Ga₂O₃ nanosheets as precursors. The 0.5 wt% Ni₂P/γ-Ga₂O₃ sample shows a photocatalytic H₂-production activity as high as 2.7 mmol g⁻¹ h⁻¹ in pure water and 12 mmol g⁻¹ h⁻¹ in an aqueous methanol solution under a 125 W high pressure mercury lamp, respectively, which are much higher than those of pure γ-Ga₂O₃ and Pt/γ-Ga₂O₃ nanosheets modified with a comparable Pt content. The Ni₂P component plays a role as an electron collector that promotes efficient separation of photogenerated electrons and holes, and thereby improves the efficiency of photocatalytic hydrogen production. The effects of inorganic and organic sacrificial reagents on the reaction efficiency and stability were observed and discussed. This work shows that Ni₂P as a cocatalyst substituting noble metals can greatly improve the photocatalytic hydrogen production efficiency of γ-Ga₂O₃ compared to that in pure water and a methanol–water solution.