Isolated Single-Atom Cobalt in the ZnIn2S4 Monolayer with Exposed Zn Sites for CO2 Photofixation

Constructing highly active photocatalysts with rich reactivesitesfor photofixation of CO2 with organic compounds implementsan environmentally friendly route for CO2 valorizationand carbon neutralization. Herein, we report the isolated cobalt (Co)single-atom (SA)-decorated two-dimensional (2D) single-layer ZnIn2S4 (ZIS) nanosheet composites (Co-(s)ZIS)with dual active centers of Co and Zn for CO2 fixationwith epoxides under visible light. The unique ensemble of Co-(s)ZIS optimizes light harvesting, promotes charge carrier separation,and enriches the bifunctional active sites for the efficient adsorptionand activation of the reactants of epoxides and CO2. Consequently,the Co-(s)ZIS exhibits significantly improved CO2-epoxide cycloaddition performance compared to bulk ZIS. In addition,the synergetic photoredox manner of simultaneously exploiting photogeneratedelectrons and holes efficiently facilitates the activation of CO2 and epoxides, thereby further reducing the energy barrierof CO2 fixation. This work not only provides a paradigmof rationally interfacial engineered SA-onto-2D semiconductors forCO(2) valorization but also highlights the structure-activityrelationship by the well-defined active sites in this SA-based hybridplatform.

Automated summary

Constructing highly active photocatalysts with rich reactive sites allows for the environmentally friendly utilization of CO2 with organic compounds. In this study, single-atom (SA) decorated two-dimensional (2D) single-layer ZnIn2S4 (ZIS) nanosheet composites with dual active centers of Co and Zn were used for CO2 fixation under visible light. The optimized Co-(s)ZIS composites exhibited significantly improved CO2-epoxide cycloaddition performance, attributing to the unique ensemble that optimizes light harvesting, promotes charge carrier separation, and enriches the bifunctional active sites. This work provides a paradigm for interfacial engineered SA-onto-2D semiconductors and highlights the structure-activity relationship by the well-defined active sites in this SA-based hybrid platform.