In Situ-Grown Island-Shaped Hollow Graphene on TaON with Spatially Separated Active Sites Achieving Enhanced Visible-Light CO<sub>2</sub> Reduction
Lang Pei, Yongjun Yuan, Wangfeng Bai, Taozhu Li, Heng Zhu, Zhanfeng Ma, Jiasong Zhong, Shicheng Yan, Zhigang Zou
Abstract
Photocatalytic CO2 reduction is hampered by the inefficient charge separation and kinetically challenging interfacial reaction. Combining nonprecious cocatalysts with semiconductors is vital for optimizing these processes. Herein, a step-by-step route is reported for the in situ growth of island-shaped graphene on TaON particles (TaON@G) with controllable distribution, targeting a superior photocatalyst for visible-light-driven CO2 reduction. The TaON@G photocatalyst possesses the snug contact interface with suitable interfacial energy levels for accelerating the charge separation, the island-shaped graphene with a hollow nanoarchitecture for facilitating the adsorption of CO2, and the hierarchical structure with spatially separated active sites for activating CO2 and promoting proton release. The optimized TaON@G achieves a visible-light-driven CO2-to-CH4 yield of 1.61 μmol g–1 h–1, which is nearly 13-fold higher compared with that of pristine TaON and outperforms most Ta-based (oxy)nitride catalysts. Density functional theory calculations further elucidate the enhanced activity, suggesting that TaON interacts with graphene strongly with the charge transfer from TaON to graphene, inducing electron-rich graphene with a significant upshift of the graphene Fermi level, leading to a high filling fraction of the antibonding orbitals, thereby weakening the C═O bond of the adsorbed CO2 for breaking. Our study highlights the importance of rational design of well-defined hierarchical photocatalysis to synergistically integrate the structural and functional advantages for maximizing catalytic performance.