Plasmonic coupling enhancement of core-shell Au@Pt assemblies on ZnIn2S4 nanosheets towards photocatalytic H2 production

Abstract

Hydrogen production via photocatalytic water splitting would be a promising technique for the utilization of hydrogen energy and solar energy. Surface plasmon resonance (SPR) of noble metal nanoparticles (NPs), such as Au, offers a fascinating arena to develop efficient photocatalysts with superior visible light harvesting properties and excellent catalytic activities. However, the photocatalytic performance enhancement based on SPR effect is limited by the relatively small contribution of the isolated plasmonic NPs. In the present work, the Au@Pt/ZnIn2S4 (ZIS) photocatalyst can be successfully constructed by the assemblies of core-shell Au@Pt NPs, consisted of plasmonic Au NP surrounded by catalytic Pt NPs, on three-dimensional (3D) ZIS microsphere in consideration of collective excitation of plasmonic NPs assemblies, demonstrating extraordinary catalytic performance of hydrogen production under visible light (≥420 nm) during water splitting process. The H2 production amount and rate over Au16@Pt/ZIS can reach 41747 μmol g−1 and 4174.7 μmol g−1h−1 under visible light, about 10 times higher than those of ZIS, respectively. The apparent quantum yield (AQY) of Au16@Pt/ZIS dramatically rises to 6.23%, nearly 10 times than that of ZIS (0.62%). Hence, the assembly formation of core-shell NPs and the introduction of ZIS can significantly enhance the photocatalytic performance of plasmonic metal NPs. The experimental results and FDTD simulation confirm that the plasmonic coupling effect of Au@Pt assemblies can generate much intensive electromagnetic (EM) field on ZIS surface, which further extends the light harvesting to visible-to-near infrared region and simultaneously boosts the generation rate of plasmon-induced hot electrons from Au and photoexcited electrons from ZIS. In addition, the Pt shell plays the role of electron sink, leading to the efficiently separation of electron-holes in Au NPs and ZIS and thus further increase the H2 evolution. All of these make Au@Pt/ZIS possess the extraordinary H2 evolution ability. We believe that the present strategy would be a significant contribution to design and prepare the efficient photocatalysts based on the plasmonic effect towards water splitting.