Electrosynthesized CuMgAl Layered Double Hydroxides as New Catalysts for the Electrochemical Reduction of CO₂

Abstract In this study, new nanostructured CuMgAl Layered Double Hydroxide (LDH) based materials are synthesized on a 4 cm 2 sized carbonaceous gas diffusion membrane. By means of microscopic and spectroscopic techniques, the catalysts are thoroughly investigated, revealing the presence of several species within the same material. By a one‐step, reproducible potentiodynamic deposition it is possible to obtain a composite with an intimate contact between a ternary CuMgAl LDH and Cu 0 /Cu 2 O species. The catalyst compositions are investigated by varying: the molar ratio between the total amount of bivalent cations and Al 3+ , the amount of loading, and the molar ratios among the three cations in the electrolyte. Each electrocatalyst has been evaluated based on the catalytic performances toward the electrochemical CO 2 reduction to CH 3 COOH at −0.4 V versus reversible hydrogen electrode in liquid phase. The optimized catalyst, that is, CuMgAl 2:1:1 LDH exhibits a productivity of 2.0 mmol CH3COOH g cat −1 h −1 . This result shows the beneficial effects of combining a material like the LDHs, alkaline in nature, and thus with a great affinity to CO 2 , with Cu 0 /Cu + species, which couples the increase of carbon sources availability at the electrode with a redox mediator capable to convert CO 2 into a C 2 product.