Dual‐Site NiO/Bi₃O₄Br Heterojunction Catalyst for High‐Efficiency CO₂‐to‐CH₄ Conversion

Abstract Solar light‐driven conversion of CO 2 into chemicals with high calorific value is regarded as an upcoming carbon utilization technology for alleviating the energy crisis. This technique faces the challenge of low CO 2 conversion and product yield due to charge recombination in the catalyst. In this paper, a dual‐reaction site heterojunction catalyst was designed and fabricated by combining NiO with Bi 3 O 4 Br nanosheets, for the separation of CO 2 reduction and H 2 O oxidation semireactions, which effectively promoted electrons and holes separation. The resulting catalyst exhibited a high CH 4 production rate (8.12 µmol/g) and selectivity (94.69%). Electron distribution and band structure were investigated to explain the satisfactory catalytic performance. In addition, combining the in‐situ DRIFTS results, a formic acid‐intermediated CO 2 ‐to‐CH 4 reaction pathway was proposed. This work aims to pave the way for CH 4 production via CO 2 photoreduction with high efficiency and selectivity.