Co engineered CoP catalyst for photochemical CO2 reduction with accelerated electron transfer endowed by the space-charge region.

[Display omitted] • The close contact between Co and CoP at the interface results in the formation of space-charge region. • The existence of space-charge region promotes the rapid transfer of electrons from Co to CoP. • Co active sites with increased electron density enhance the adsorption and activation ability of CO 2. • The high-speed reduction of CO 2 was realized by reducing the activation energy barriers. Photocatalytic CO 2 reduction has been regarded as an ideal method to simulate photosynthesis for achieving carbon neutralization. However, poor charge transfer efficiency limits its development. Herein, an efficient Co/CoP@C catalyst was prepared with compact contact of Co and CoP layer by using MOF as precursor. At the interface of Co/CoP, the difference in functionality between the two phases may result in uneven distribution of electrons, thus forming a self-driven space-chare region. In this region, spontaneous electron transfer is guaranteed, thus facilitating the effective separation of photogenerated carriers as well as boosting the utilization of solar energy. Furthermore, the electron density of active site Co in CoP is increased and more active sites are exposed, which promotes the adsorption and activation of CO 2 molecules. Together with suitable redox potential, low energy barrier for *COOH formation and easy desorption of CO, the reduction rate of CO 2 catalyzed by Co/CoP@C is 4 times higher than that of CoP@C. [ABSTRACT FROM AUTHOR]