Highly electrocatalytic activity and excellent methanol tolerance of hexagonal spinel-type Mn₂AlO₄ nanosheets towards oxygen reduction reaction: Experiment and density functional theory calculation

Highlights: • Hexagonal spinel-type Mn₂AlO₄ nanosheets were fabricated by dealloying/annealing. • The Mn₂AlO₄ nanosheets exhibit a high BET surface area of up to 164 m² g⁻¹. • Mn₂AlO₄ nanosheets show superior catalytic activity and methanol tolerance in ORR. • The RDE, RRDE and DFT results confirm the 4e⁻ pathway for ORR on Mn₂AlO₄. Oxygen reduction reaction (ORR) is of crucial importance in fuel cells and metal–air batteries, however, the sluggish dynamics of ORR remains a critical issue to be addressed. Here, we report the preparation of hexagonal spinel-type Mn₂AlO₄ nanosheets with a high BET surface area of up to 164 m² g⁻¹ through a dealloying–annealing strategy. The Mn₂AlO₄ catalyst shows a good catalytic activity towards ORR in the alkaline solution, as well as much better methanol tolerance than the commercial Pt/C. Moreover, both the electrochemical measurements and density functional theory (DFT) calculations (adsorption energy, density of states, H₂O₂ decomposition) demonstrate that the ORR on Mn₂AlO₄ is a four-electron pathway. In addition, the DFT results expound the reason why the Mn₂AlO₄ catalyst has much better methanol tolerance than Pt/C.