Phase-Modulated Reaction Kinetics on ZnIn 2 S 4 /In 2 O 3 Heterostructures for Photocatalytic CO 2 Reduction

Photochemically upcycling CO2 to valuable carbon derivatives offers a very promising solution to reduce carbon emission. Constructing heterostructured photocatalysts has become the preferred approach for achieving high product yield, yet methods to elaborately refine the design of heterostructures to further enhance the reaction kinetics remains to be explored. Here, we propose a phase-modulated reaction kinetics strategy to enhance the performance of photocatalytic CO2-to-CO conversion over the ZnIn2S4/In2O3 heterostructure. Notably, obtained ZnIn2S4/cubic In2O3 achieved a high CO yield of 439.7 μmol g–1 h–1 in the presence of triethanolamine (TEOA) as a hole scavenger, almost 3-fold higher than that of ZnIn2S4/rhombohedral In2O3, and an order of magnitude higher than that of individual counterparts. Experimental and theoretical results revealed that ZnIn2S4/cubic-In2O3 shows a better charge transfer and separation efficiency, a higher CO2 adsorption and activation capacity, and a lower energy barrier of the key rate-determining step (*COOH → *CO), which synergistically facilitate the CO2 reduction kinetics. This work highlights that crystal-phase engineering plays a critical role in regulating the reaction kinetics, providing insights into the design of highly efficient heterostructured catalysts for photocatalysis.