Bimetallic nanoparticles as cocatalysts for versatile photoredox catalysis

Semiconductor photocatalysis is considered as a cutting-edge research topic for the production of value-added fuels and chemicals to confront the global energy crisis. In order to improve the solar-to-chemical conversion efficiency of pristine semiconductors, combining them with cocatalysts to form heterostructures has been extensively investigated. Among studied formulations, bimetallic nanoparticles (NPs), featuring enhanced light harvesting, efficient capture of photogenerated electrons and abundant surface active sites are ideal cocatalysts to improve the photocatalytic performance of semiconductor-based photocatalysts. In this review, we begin with a concise overview of representative synthesis and characterization methods of bimetallic NPs. Then, we predominantly summarize the typical applications of semiconductor/bimetallic NPs-based composites in photoredox catalysis, including hydrogen evolution, carbon dioxide reduction, selective organic synthesis and environmental remediation. In particular, we highlight the regulatory effects of parameters of bimetallic NPs (composition, structure, morphology, size, atomic arrangement, loading position, etc.) on the photocatalytic activity and selectivity. Finally, the remaining challenges and future perspectives for the utilization of bimetallic NPs in photoredox catalysis are discussed and anticipated to stimulate the sparkling ideas in the construction of high-efficiency semiconductor/bimetallic NPs-based photocatalytic systems.