Au–Pt alloy nanoparticles site-selectively deposited on CaIn2S4 nanosteps as efficient photocatalysts for hydrogen production

Abstract

Au–Pt/CaIn₂S₄ composites were synthesized for the first time using the photoreduction method by which bimetallic Au–Pt alloy nanoparticles were in situ site-selectively photoreduced on the edges of monoclinic CaIn₂S₄ nanosteps. The Au–Pt alloy nanoparticles as cocatalysts can spatially separate the oxidation and reduction sites and effectively enhance the photocatalytic hydrogen activity of CaIn₂S₄ under visible light irradiation. When introducing 0.5 wt% Au–Pt alloy nanoparticles, the rate of hydrogen production could reach 107.6 μmol h⁻¹, which was higher than that of CaIn₂S₄, Au/CaIn₂S₄ and Pt/CaIn₂S₄ by a factor of 18.3, 2.37 and 2.4, respectively. The enhanced photocatalytic activity for hydrogen production could be attributed to the low recombination efficiency of the photogenerated charges and surface-plasmon-resonance-induced effect of Au nanoparticles.