Regulating interfacial dual active sites on Co/N carbon nanocages enables oriented charge flow on ZnIn2S4 for cooperative photocatalytic hydrogen evolution and highly selective oxidation
Sijia Liu, Jiangjie Zhan, Changqing Yang, Chaohai Wei, Yun Hu
Abstract
The photocatalytic cooperative hydrogen evolution and alcohol oxidation process for producing of two valuable products is highly attractive strategy, but optimizing active sites and constructing dual-function photocatalysts with high activity and selectivity remains challenging. In this study, dual active sites photocatalysts of Co/N-doped graphitic carbon nanocages (CoNC)/ZnIn 2 S 4 nanosheets (ZIS) were successfully prepared, where the Co atom anchoring on N-doped carbon (Co-N structure) and Co nanoparticles (Co NPs) encapsulating in layered graphitic carbons, resulting in the simultaneous photocatalytic hydrogen production and selective oxidation of benzyl alcohol to benzaldehyde. After regulating the active sites ratio of Co NPs/Co-N, the CoNC/ZIS exhibited an excellent hydrogen production rate (2334 μmol g⁻¹h⁻¹) and benzaldehyde production yield (2825 μmol g⁻¹h⁻¹), which were 9.0 times and 17.5 times than that of pure ZIS, respectively. The characterization results indicated that the Co-N structure served as electron-rich sites and Co NPs served as sites for dehydrogenation, promoting directed electron-hole migration and providing sufficient the optimum reaction sites for hydrogen evolution and benzyl alcohol oxidation. Furthermore, the CoNC optimized structure and interface environment of ZIS, by reducing the potential of the valence band edge and enhancing the adsorption energy for benzaldehyde, thereby effectively improving the selectivity for benzaldehyde (increased from 47.9 % to 99.2 %). Based on DFT calculations, that the synergy of interfacial Co-N structure and Co NPs played a critical role in the coupled photocatalytic system and enhanced photogenerated carrier utilization. This study suggests new avenues to the design of a dual-function photocatalyst for significantly improve the utilization efficiency of solar energy. • A dual-functional photocatalyst was prepared for H 2 evolution coupling with benzyl alcohol selectivity oxidation. • Co-N structure promoted electron enrichment and H 2 evolution, while Co NPs served as sites for dehydrogenation. • CoNC optimized structure and interface environment of ZIS, effectively improving the selectivity for benzaldehyde. • The coupled system achieved the and directed migration and full utilization of electron holes.