Electrochemical insights into layered La2CuO4 perovskite: Active ionic copper for selective CO2 electroreduction at low overpotential.

La 2 CuO 4 , a layered perovskites oxide was synthesized using solution combustion method at different calcination temperatures. XRD characterization and Rietveld refinement analysis confirms the pure phase of the synthesized material. The effect of calcination causes shrinking in the lattice parameters affirm the change in the oxygen stoichiometry. Four Probe (Van der Pauw's) and CP-AFM analysis were carried out to understand the influences of calcination temperature on electrical conductivity. Electrochemical investigations on La 2 CuO 4 were performed at various negative potential ranges using cyclic voltammetry (CV) to identify the redox active centre. Thermodynamic calculations are further carried out to validate the electrochemical results in different mediums. Selective electrocatalytic conversion of CO 2 to C 2 -hydrocarbon (C 2 H 4) with FE% of 40.3% which is 10 times higher than CH 4 (FE% = 4.1%) emphasized the in-situ formation of Cu 2 O from the redox active centre present in La 2 CuO 4. Hydrocarbons are generated at a very low overvoltage (−0.4 V RHE) in comparison to literature. XPS analysis indeed confirms the presence of Cu+ species i.e., in-situ generated Cu 2 O, on La 2 CuO 4 after CV and CO 2 electrocatalysis. Image 108061 • In the present study, we have explored the electrochemical behavior of redox active centre 'Cu2+' in a highly crystalline layered La 2 CuO 4 perovskite. • During electrochemical reduction, La 2 CuO 4 breaks into La 2 O 3 and Cu 2 O. This Cu 2 O further undergo reduction and forms Cu metal which is a reversible reaction. • Thermodynamic calculations aided in understanding the electrochemical in-situ formation of Cu 2 O. • Selective electrocatalytic reduction of CO 2 to C 2 H 4 (10 times higher than CH 4), at −0.4 V RHE, very low overpotential, emphasis the typical behaviour of Cu 2 O. • XPS analysis confirms the presence of Cu+ species (i.e., Cu 2 O) after electrochemical treatment of La 2 CuO 4 and retained after selective CO 2 electrocatalysis. [ABSTRACT FROM AUTHOR]