Praseodymium-based mixed metal oxides as stable and CO-resistant electrocatalysts for methanol oxidation in acidic media

Abstract

In this study, we report for the first time the electrocatalytic performance of Pr-based metal oxides, PrCuO (PCO), PrNiO (PNO), and PrZnO (PZO), toward methanol electro-oxidation. Results show that PCO exhibits superior activity with a low onset potential of 0.96 V vs. RHE and strong resistance to CO poisoning. Electrochemical impedance spectroscopy (EIS) reveals a low charge transfer resistance (R_ct), indicating fast electron transfer kinetics. Mass activity of PCO reaches 0.75 A mg⁻¹, surpassing the various Pt-based catalysts such as Pt₆₂Ru₃₅/C (0.47 A mg⁻¹), Pt₆₂Ru₁₈Ni₂₀–O/C (0.30 A mg⁻¹), and PtZn NPs (0.58 A mg⁻¹). Density functional theory (DFT) calculations indicate that PCO facilitates methanol oxidation via a COH* intermediate, enhancing CO oxidation and CO₂ evolution. The favorable d-band center and strong Cu 3d–O 2p orbital interaction contribute to its high activity. These findings establish PCO as a promising and durable electrocatalyst for energy conversion applications.