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

Photochemically upcycling CO 2 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 CO 2 -to-CO conversion over the ZnIn 2 S 4 /In 2 O 3 heterostructure. Notably, obtained ZnIn 2 S 4 /cubic In 2 O 3 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 ZnIn 2 S 4 /rhombohedral In 2 O 3, and an order of magnitude higher than that of individual counterparts. Experimental and theoretical results revealed that ZnIn 2 S 4 /cubic-In 2 O 3 shows a better charge transfer and separation efficiency, a higher CO 2 adsorption and activation capacity, and a lower energy barrier of the key rate-determining step (*COOH → *CO), which synergistically facilitate the CO 2 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.