Modulating Electronic States of Cu in Metal-Organic Frameworks for Emerging Controllable CH 4 /C 2 H 4 Selectivity in CO 2 Electroreduction.

The intensive study of electrochemical CO 2 reduction reaction (CO 2 RR) has resulted in numerous highly selective catalysts, however, most of these still exhibit uncontrollable selectivity. Here, it is reported for the first time the controllable CH 4 /C 2 H 4 selectivity by modulating the electronic states of Cu incorporated in metal-organic frameworks with different functional ligands, achieving a Faradaic efficiency of 58% for CH 4 on Cu-incorporated UiO-66-H (Ce) composite catalysts, Cu/UiO-66-H (Ce) and that of 44% for C 2 H 4 on Cu/UiO-66-F (Ce). In situ measurements of Raman and X-ray absorption spectra revealed that the electron-withdrawing ability of the ligand side group controls the product selectivity on MOFs through the modulation of the electronic states of Cu. This work opens new prospects for the development of MOFs as a platform for the tailored tuning of selectivity in CO 2 RR.