Auto-Tandem Co2 Reduction by Reconstructed Cu Imidazole Framework Isomers: Unveiling Pristine Mof-Mediated Co2 Activation

Cu-based metal-organic frameworks (MOFs) are widely employed in CO2 reduction reactions (CO2RR). Mostly, the in-situ reconstructed derivatives such as Cu or Cu oxides during CO2RR are regarded as the catalytic active center for the formation of catalytic products. However, in many cases, the pristine MOFs still exist during the catalytic process, the key role of these pristine MOFs is often ignored in revealing the catalytic mechanism. Here, we designed two Cu(imidazole) with different coordination environments, namely CuN2 and Cu2N4 for CO2RR. The structures of the two MOFs were still remained after the catalytic reaction. We discovered that the pristine MOFs served as activation catalysts for converting CO2 into CO. Sequentially, the Cu-based derivatives, in the two cases, Cu(111) converted the CO into C2+ products. The CuN2 with more exposed Cu-N centers showed a higher FECO and a higher final FEC2+ than Cu2N4. This auto-tandem catalytic mechanism was supported by electrocatalytic performance, TPD-CO, HRTEM, SAED, XPS, in-situ XANES and XES and DFT computation. The auto-tandem catalytic mechanism provides a new route to design Cu-based MOF electrocatalysts for high product selectivity in CO2RR.