Coaxially Bi/ZnO@ZnSe array photocathode enables highly efficient CO2 to C1 conversion via long‐lived high‐energy photoelectrons

The key aspect of the photoelectrochemical CO2 reduction reaction (PEC CO2 RR) lies in designing cathode materials that can generate high‐energy photoelectrons, enabling the activation and conversion of CO2 into high‐value products. In this study, a coaxially wrapped ZnO@ZnSe array heterostructure was synthesized using a simple anion exchange strategy and metallic Bi nanoparticles (NPs) were subsequently deposited on the surface to construct a Bi/ZnO@ZnSe photocathode with high CO2 conversion capability. This array photocathode possesses a large aspect ratio, which simultaneously satisfies a low charge carrier migration path and a large specific surface area that facilitates mass transfer. Additionally, the barrier formed at the n‐n heterojunction interface hinders the transfer of high‐energy photoelectrons from ZnSe to lower energy levels, resulting in their rapid capture by Bi while maintaining a relatively long lifetime. These captured electrons act as active sites, efficiently converting CO2 into CO with a Faradaic efficiency above 88.9% at ‐0.9 V vs. RHE and demonstrating superior stability. This work provides a novel approach for synthesizing high‐energy photoelectrode materials with long lifetimes.