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

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/Cu2O species. The catalyst compositions are investigated by varying: the molar ratio between the total amount of bivalent cations and Al3+, 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 CO2 reduction to CH3COOH 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 CO2, with Cu-0/Cu+ species, which couples the increase of carbon sources availability at the electrode with a redox mediator capable to convert CO2 into a C-2 product.