Tuning CuMgAl-Layered Double Hydroxide Nanostructures to Achieve CH 4 and C 2+ Product Selectivity in CO 2 Electroreduction.

Electrochemical CO 2 reduction reaction (eCO 2 RR) over Cu-based catalysts is a promising approach for efficiently converting CO 2 into value-added chemicals and alternative fuels. However, achieving controllable product selectivity from eCO 2 RR remains challenging because of the difficulty in controlling the oxidation states of Cu against robust structural reconstructions during the eCO 2 RR. Herein, we report a novel strategy for tuning the oxidation states of Cu species and achieving eCO 2 RR product selectivity by adjusting the Cu content in CuMgAl-layered double hydroxide (LDH)-based catalysts. In this strategy, the highly stable Cu 2+ species in low-Cu-containing LDHs facilitated the strong adsorption of *CO intermediates and further hydrogenation into CH 4 . Conversely, the mixed Cu 0 /Cu + species in high-Cu-containing LDHs derived from the electroreduction during the eCO 2 RR accelerated C-C coupling reactions. This strategy to regulate Cu oxidation states using LDH nanostructures with low and high Cu molar ratios produced an excellent eCO 2 RR performance for CH 4 and C 2+ products, respectively.