Elucidating the Effects of Electrolytes on a Robust MOF Interface for Enhanced CO2 Electroreduction to C2 Products

Elucidating the role of electrolytes in steering CO 2 electroreduction toward C 2+ products is critical, yet impeded by dynamic electrocatalyst reconstruction during the CO 2 RR. Herein, we successfully prepared a novel Cu-based metal–organic framework (Cu-BDP, BDP = 1,4-benzenedipyrazolate) with robust Cu–N 4 coordination. Bode phase analysis and contact angle measurements demonstrate that Cs + cations facilitate interfacial charge transfer and establish local hydrophobic microenvironments to suppress hydrogen evolution reactions. Meanwhile, adsorbed I – anions generate more accessible active sites. As a result, in the optimized CsI electrolyte, a high C 2 Faradaic efficiency of 50.34% is achieved at −1.6 V vs RHE. Density functional theory (DFT) calculations reveal that I – anions preferentially facilitate initial CO 2 activation and stabilize single *CO intermediates, while Cs + cations promote the enrichment of multi-CO intermediates and the hydrogenation of *OCCO to *OCCOH on the Cu-BDP surface. Furthermore, the synergistic effect of the Cs + /I – binary electrolyte system significantly reduces the energy barrier for C–C coupling compared to electrolytes containing only Cs + or I – ions. This work provides insights into the synergistic effect of electrolyte cations and halide ions on CO 2 electroreduction.