Au–Ag alloy nanoparticles with tunable cavity for plasmon-enhanced photocatalytic H2 evolution

Au–Ag alloy nanoparticles with different cavity sizes have great potential for improving photocatalytic performance due to their tunable plasmon effect. In this study, galvanic replacement was combined with co-reduction with the reaction kinetics processes regulated to rapidly synthesize Au–Ag hollow alloy nanoparticles with tunable cavity sizes. The position of the localized surface plasmon resonance (LSPR) peak could be effectively adjusted between 490 nm and 713 nm by decreasing the cavity size of the Au–Ag hollow nanoparticles from 35 nm to 20 nm. The plasmon-enhanced photocatalytic H2 evolution of alloy nanoparticles with different cavity sizes was investigated. Compared with pure P25 (TiO2), intact and thin-shelled Au–Ag hollow nanoparticles (HNPs)-supported photocatalyst exhibited an increase in the photocatalytic H2 evolution rate from 0.48 µmol h−1 to 4 µmol h−1 under full-spectrum irradiation. This improved photocatalytic performance was likely due to the plasmon-induced electromagnetic field effect, which caused strong photogenerated charge separation, rather than the generation of hot electrons.