Internal electric field-induced photocatalytic conversion of CO2 to CH4 in CeO2(110)/g-C3N4 heterojunctions

Solar-driven carbon dioxide reduction (CO 2 RR) is a highly promising strategy for closing the carbon cycle and enabling the sustainable production of clean chemicals. However, its practical efficiency remains severely limited by sluggish reaction kinetics and competing reaction pathways. In this study, through rational interfacial engineering to induce a stable built-in electric field, we constructed an S-scheme heterojunction based on CeO 2 (110)/g-C 3 N 4 to achieve coordinated modulation of photocatalytic CO 2 reduction. Under gas-solid-phase reaction conditions without a sacrificial agent, the catalyst delivered a yield of 2.51 μmol·g −1 ·h −1 , representing an 8.05-fold enhancement compared with pristine g-C 3 N 4 . A series of experimental investigations indicate that the internal electric field not only promotes the efficient separation and migration of photogenerated carriers but also strengthens CO 2 adsorption and activation, thereby steering the original CO-forming pathway toward an eight-electron-dominated CH 4 pathway. This work may offer a viable heterojunction design strategy for achieving selective CO 2 RR.