La-based Transition Metal Oxide Perovskites as Electrocatalysts for Electrochemical Carbon Dioxide Reduction

We report here the feasibility of using LaT M O 3 -based perovskites (T M = Co, Cr, Fe, Mn, Ni, i.e., non-Cu 3d transition metals) as electrocatalysts for electrochemical CO 2 reduction reaction (eCO 2 RR). Phase pure LaT M O 3 perovskites, having T M -ions in multiple oxidation states for all and O-defects for LaFeO 3 and LaNiO 3 , have been synthesized and tested as electrocatalysts for eCO 2 RR in flow cell type set-up. The above characteristics of the La-T M -oxides have been found to influence the current densities during eCO 2 RR at the various applied potentials, with favorable effects of the presence of O-defects (as for LaFeO 3 and LaNiO 3 ). Upon eCO 2 RR, both C 1 and C 2 liquid products have been obtained, including ethanol, with a partial current density of −2.66 mA cm −2 at −1.2 V vs RHE (for LaFeO 3 ). The types of products and the faradic efficiencies have been found to depend on the T M -ion present (in the LaT M O 3 ); in particular, the oxidation state(s), associated O-defect(s) and electronic conductivity. Furthermore, the electrocatalysts have been found to be stable during eCO 2 RR. Overall, the present work highlights the potential of La-T M -oxide perovskites for usage as stable electrocatalysts for eCO 2 RR, and also provides insights into the proper selection of “T M ” and reaction conditions for obtaining the desired product(s).