In this paper, Pt3Ni alloy polyhedral was synthesized through solvothermal method and loaded on the surface of CdS by photo-induced electrons. Under visible light irradiation, the photocatalytic activity for hydrogen evolution from solar water splitting was performed, Pt3Ni/CdS showed the hydrogen evolution rate about 40.0 mmol/h/g (QE = 44.90%, lambda = 420 nm), which was 1.8 times higher than that of Pt/CdS, indicating that Pt3Ni NPs could effectively improve the hydrogen production activity of CdS. Next, the influence of de alloyed Pt3Ni NPs on the activity of CdS for water-splitting under visible light was investigated, the hydrogen evolution rate of de-alloyed Pt3Ni NPs modified CdS was 46.1 mmol/h/g (QE = 52.70%, lambda = 420 nm), which was 1.2 times as much as that of Pt3Ni/CdS and 2.1 times as much as that of Pt/CdS, suggesting that de-alloyed Pt3Ni NPs could further enhance the hydrogen production activity of CdS. In addition, the improved photocatalytic activity was mainly due to the surface unsaturation of Pt atoms in a metastable structure after de-alloying, which will expose more surface active sites of Pt, thus the fast electron hole charge transfer at the interface of CdS and de-alloyed Pt3Ni NPs. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.