Self-assembly of Ni 2 P/γ-Ga 2 O 3 nanosheets for efficient photocatalytic water splitting hydrogen production.

The development of photocatalysts enabling stable and highly efficient water splitting hydrogen production remains an open challenge in the field of energy photocatalysis. Herein, Ni 2 P/γ-Ga 2 O 3 nanosheets have been reported as excellent water splitting photocatalysts. Ni 2 P particles and γ-Ga 2 O 3 nanosheets were synthesized by a facile hydrothermal process. The Ni 2 P/γ-Ga 2 O 3 samples were prepared by an electrostatic self-assembly method with Ni 2 P particles and γ-Ga 2 O 3 nanosheets as precursors. The 0.5 wt% Ni 2 P/γ-Ga 2 O 3 sample shows a photocatalytic H 2 -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-Ga 2 O 3 and Pt/γ-Ga 2 O 3 nanosheets modified with a comparable Pt content. The Ni 2 P 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 Ni 2 P as a cocatalyst substituting noble metals can greatly improve the photocatalytic hydrogen production efficiency of γ-Ga 2 O 3 compared to that in pure water and a methanol-water solution.