Increasing electrochemical carbon dioxide reduction to methane via a novel copper-based conductive metal organic framework.

The development of a new system for the electrochemical carbon dioxide reduction reaction (ECORR) to methane (CH) is challenging, and novel conductive metal organic frameworks (c-MOFs) for efficient ECORR to CH are critical to this system. Here, we report a novel c-MOF, copper-pyromellitic dianhydride-2-methylbenzimidazole (Cu-PD-2-MBI), in which the introduction of electron-withdrawing 2-methylbenzimidazole (2-MBI) into the copper-pyromellitic dianhydride (Cu-PD) interlayer elevated the valence of copper (Cu) ions, which improved the ECORR performance of Cu-PD-2-MBI. Cu-PD-2-MBI was tested in a flow cell, and the Faradaic efficiency of CH reached 73.7 %, with a corresponding partial current density of -428.3 mA·cm at -1.3 V, which was higher than those of most reported Cu-based catalysts. Further exploration via theoretical calculations indicated that the intercalated 2-MBI in Cu-PD-2-MBI induced a shift in the d-band center in the Cu sites from -2.63 to -1.86 eV and reduced the formation energy of the *COOH and *CHO intermediates in the process of generating CH compared with those of the reference Cu-PD catalyst.