Nickel metal-organic frameworks for visible-light CO reduction under mild reaction conditions.

Photochemical CO 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 CO reduction. Herein, we demonstrate the effect of Ni metal centers as catalytic active sites for the photocatalytic conversion of CO to CO by designing and constructing Ni metal-organic framework (Ni-MOF) materials. In pure CO, Ni-MOF catalyst exhibits outstanding performance for visible-light-driven reductive CO deoxygenation with a high CO evolution rate of 19.13 μmol h (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 CO photoreduction and low CO selectivity (40.1%) were observed, implying that the performance of CO photoreduction and CO selectivity are dependent on unsaturated metal centers.