Methanol electro-oxidation to formate on iron-substituted lanthanum cobaltite perovskite oxides

Electrochemically producing formate by oxidizing methanol is a promising way to add value to methanol. Noble metal-based electrocatalysts, which have been extensively studied for the methanol oxidation reaction, can catalyze the complete oxidation of methanol to carbon dioxide, but not the mild oxidation to formate. As a result, exploring efficient and earth-abundant electrocatalysts for formate production from methanol is of interest. Herein, we present the electro-oxidation of methanol to formate, catalyzed by iron-substituted lanthanum cobaltite (LaCo_1−xFe_xO₃). The Fe/Co ratio in the oxides greatly influences the activity and selectivity. This effect is attributed to the higher affinity of Fe and Co to the two reactants: CH₃OH and OH⁻, respectively. Because a balance between these affinities is favored, LaCo_0.5Fe_0.5O₃ shows the highest formate production rate, at 24.5 mmol ​h⁻¹ g_oxide⁻¹, and a relatively high Faradaic efficiency of 44.4% in a series of (LaCo_1−xFe_xO₃) samples (x ​= ​0.00, 0.25, 0.50, 0.75, 1.00) at 1.6 ​V versus a reversible hydrogen electrode.