Nickel metal–organic frameworks for visible-light CO2 reduction under mild reaction conditions

Photochemical CO2 conversion into carbon fuel is a promising route to explore renewable energy and relieve climate change. However, it is still a key challenge to achieve high selectivity to CO and simultaneously achieve high conversion efficiency in photochemical CO2 reduction. Herein, we demonstrate the effect of Ni metal centers as catalytic active sites for the photocatalytic conversion of CO2 to CO by designing and constructing Ni metal–organic framework (Ni-MOF) materials. In pure CO2, Ni-MOF catalyst exhibits outstanding performance for visible-light-driven reductive CO2 deoxygenation with a high CO evolution rate of 19.13 μmol h−1 (per 1 mg of catalyst) and CO selectivity of 91.4%, which exceeds those of most reported systems. Upon using isostructural Co-MOF as the catalyst to replace Ni-MOF, a moderate performance towards CO2 photoreduction and low CO selectivity (40.1%) were observed, implying that the performance of CO2 photoreduction and CO selectivity are dependent on unsaturated metal centers.