Interfacial Charge‐Transfer Dynamics in a Three‐Dimensional ZnO Nanorod/CsPbBr ₃ Heterostructured Filter for CO ₂ Photoreduction

Understanding how interfacial electronic structure governs photogenerated charge flow is central to advancing heterogeneous photocatalysis. Herein, a three‐dimensional ZnO/CsPbBr ₃ nanoheterostructure (NHS) system is constructed to elucidate the relationship between band alignment, carrier dynamics, and photocatalytic CO ₂ reduction under solid–gas conditions using CO ₂ and H ₂ O as reactants. Ultraviolet photoelectron spectroscopy reveals staggered band alignment that enables formation of an S‐scheme heterojunction with an internal electric field at the ZnO/CsPbBr ₃ interface. This configuration preserves the strong reduction potential of CsPbBr ₃ and the oxidation capability of ZnO while promoting directional recombination of low‐energy carriers and spatial separation of highly reactive electrons and holes. The investigation of charge carrier dynamics demonstrates accelerated interfacial electron migration and enhanced carrier separation in the optimized heterostructure. The apparent quantum efficiency follows the optical absorption profile, confirming efficient photon‐to‐chemical energy conversion. ¹³ C isotope labeling verifies that CO originates from CO ₂ reduction accompanied by H ₂ O oxidation. A clear correlation between band alignment, carrier lifetime modulation, interfacial charge‐transfer rate, and catalytic activity is established, providing mechanistic insight into interfacial photochemistry in perovskite–metal oxide heterostructures for solar fuel generation.