Ultrasmall MoO x Clusters as a Novel Cocatalyst for Photocatalytic Hydrogen Evolution

To enhance the performance of semiconductor photocatalysts, cocatalysts are used to accelerate surface reactions. Herein, ultrasmall molybdenum–oxygen (MoO x ) clusters are developed as a novel non-noble cocatalyst, which significantly promotes the photocatalytic hydrogen generation rate of CdS nanowires (NWs). As indicated by extended X-ray absorption fine structure analysis, direct bonds are formed between CdS NWs and MoO x clusters, which guarantee the migration of photo-generated charge carriers. Moreover, the MoO x clusters induce deep electron trap states owing to the unique atomic arrangement and configuration with the generation of long-lived electrons to enhance the activity. These findings may guide the design of efficient cocatalytic materials for solar water splitting and open a new avenue toward practical applications of ultrasmall clusters.