Enhanced Photocatalytic Hydrogen Evolution by Loading Cd_0.5Zn_0.5S QDs onto Ni₂P Porous Nanosheets

Ni₂P has been decorated on CdS nanowires or nanorods for efficient photocatalytic H₂ production, whereas the specific surface area remains limited because of the large size. Here, the composites of Cd_0.5Zn_0.5S quantum dots (QDs) on thin Ni₂P porous nanosheets with high specific surface area were constructed for noble metal-free photocatalytic H₂ generation. The porous Ni₂P nanosheets, which were formed by the interconnection of 15-30 nm-sized Ni₂P nanoparticles, allowed the uniform loading of 7 nm-sized Cd_0.5Zn_0.5S QDs and the loading density being controllable. By tuning the content of Ni₂P, H₂ generation rates of 43.3 μM h^- 1 (1 mg photocatalyst) and 700 μM h^- 1 (100 mg photocatalyst) and a solar to hydrogen efficiency of 1.5% were achieved for the Ni₂P-Cd_0.5Zn_0.5S composites. The effect of Ni₂P content on the light absorption, photoluminescence, and electrochemical property of the composite was systematically studied. Together with the band structure calculation based on density functional theory, the promotion of Ni₂P in charge transfer and HER activity together with the shading effect on light absorption were revealed. Such a strategy can be applied to other photocatalysts toward efficient solar hydrogen generation.