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).