Photocatalytic hydrogen production over plasmonic AuCu/CaIn2S4 composites with different AuCu atomic arrangements

Plasmonic AuCu bimetallic nanoparticles supported on monoclinic CaIn2S4 have been synthesized through the photoreduction method, by which AuCu bimetallic nanoparticles with different atomic arrangements were site-selectively photo-deposited at the edges of CaIn2S4 surface nanosteps. The obtained plasmonic composites were characterized by XRD, TEM, photoelectrochemical analysis, XPS, UV–vis and PL spectroscopy. The results showed that AuCu bimetallic nanoparticles with alloy structure showed better performance for light absorption, charge separation and photocatalytic activity compared to AuCu core-shell structure. Especially, alloyed Au0.4Cu0.1/CaIn2S4 composite exhibited the highest visible activity for hydrogen production from Na2S/Na2SO3 solution with a rate of 452.8 μmol/h, over 2.2, 10.0, 63.8 and 76.7 times higher than that of core-shell Cu0.1/Au0.4/CaIn2S4, Au0.5/CaIn2S4, Cu0.5/CaIn2S4 and CaIn2S4, respectively. The enhanced photocatalytic performance of AuCu/CaIn2S4 composites could be mainly ascribed to the synergistic effect in AuCu bimetallic nanoparticles and the surface plasmon resonance effect of Au.