Construction of N-doped copper metal-organic frameworks for promoting photocatalytic carbon dioxide reduction to ethylene

Engineering nonmetallic atom-doped metal-organic framework (MOF) catalyst to promote C-C coupling and realize conversion of CO2 into C2 multi-carbon hydrocarbon products is still challenging. Herein, with 2-methylimidazole as a dopant of N element, an N-doped NH2-CuBDC catalyst was obtained via a facile and simple stirring procedure. Upon illumination, compared with catalytic CO2 reduction to C1 product of CO by original MOF, N-doped NH2-CuBDC can motivate generation of C2H4, which is difficult to achieve in photocatalytic system by MOF-based catalysts. The transfer rates of photo-generated charges have been expedited due to the high electron density around Cu catalytic sites after N-doping. More importantly, C-C coupling intermediate CO-CHO* was identified by in situ Fourier transform infrared spectroscopy during the catalytic CO2 reduction reaction process, which further indicates the presence of Cu-N sites in the NH2-CuBDC can facilitate the formation of C2H4 effectively. This work uncovers a new paradigm to design photocatalysts for enhancing the reduction of CO2 to C2 products.