Synchronous fabrication of Ru single atoms and RuO2 on hierarchical TiO2 spheres for enhanced photocatalytic coproduction of H2 and benzaldehyde

Photocatalytic water splitting coupled with selective organic oxidation can simultaneously produce clean H2 fuel and value-added chemicals by effective utilization of photoexcited electrons and holes. However, significant challenges remain in developing the dual-function photocatalysts with high performance. Herein, well-dispersed Ru single atoms (RuSA) and RuO2 nanoparticles are synchronously anchored on hierarchical TiO2 sub-microspheres to fabricate a superb dual-function photocatalyst (RuSA-RuO2/TiO2) for accelerating the coproduction of hydrogen and benzaldehyde from benzyl-alcohol aqueous solution. The hierarchical TiO2 spheres with a high specific surface area act not only a light-harvesting material but also a favorable support for exposing more catalytic sites. The one-step modification of dual cocatalysts on semiconductor is more attractive than the complicated multi-step process. Under a simulated sunlight, the yield rates of hydrogen and benzaldehyde reach up to 2.91 and 1.42 mmol·gcat-1·h−1, respectively, much higher than those obtained from the prepared photocatalysts with other modifications. Mechanistic investigations by control experiments, detailed characterizations and theoretical calculations elucidate the synergetic catalysis of Ru single atoms and RuO2 nanoparticles on TiO2, which facilitates the separation of photo-generated charge carriers as well as affords the specific active sites for hydrogen evolution and benzaldehyde production. This work provides a facile strategy to develop high-performance photocatalysts for sustainable energy conversion as well as a new insight into the synergistic catalysis of different active sites.