SO42− mediated CO2 activation on metal electrode for efficient CO2 electroreduction

The most difficulty of efficient CO 2 electroreduction lies in the activation step that turns CO 2 into the CO 2 − radicals or other intermediates that can be further converted. To overcome this bottleneck, many efforts have been devoted to develop electrocatalysts to lower the overpotential of CO 2 activation, but they inevitably involve complicated or/and unscalable synthesis methods. Here we reported that the SO 4 2− ion modified metal foils, including Zn, Ag, Au and Cu, demonstrated ∼6.5, 1.4, 14 and 2.5 times of CO faradaic efficiency in K 2 SO 4 electrolyte compared to KHCO 3 electrolyte at −1.05 V vs. RHE. According to both experimental and DFT studies, the electron-rich metal-SO 4 adlayer can activate CO 2 by bending the linear molecule of CO 2 through donating electrons to the antibonding orbital of CO 2 , thus facilitating the formation of key intermediate *CO 2 − . Moreover, the adsorption of H + on metal sites is restrained by the metal-SO 4 adlayer, leading to a suppressed H 2 evolution activity. From a broader perspective, many catalysts can benefit from this approach to achieve more efficient CO 2 electrochemical reduction.