Tailoring efficient and chlorine-resistant oxygen reduction electrocatalyst based on 4f-2p-5d gradient orbital coupling

The development of efficient oxygen reduction reaction (ORR) electrocatalysts that utilize seawater as an electrolyte is crucial for harnessing marine resources and advancing the application of zinc-air batteries (ZABs). Here, Er₂O₃-Pt electrocatalysts enriched oxygen vacancies were constructed by a one-step microwave method. Theoretical calculations indicate that the unique 4f orbitals of Er, in conjunction with the Pt 5d and O 2p orbitals, allow the 4f electrons to demonstrate a degree of mobility. This behavior provides flexible electronic states and optimizes the binding strength of oxygen intermediates in the ORR. In addition, quasi in-situ characterization has proven that the addition of Er and the mediation of the oxygen vacancies have enriched the electrons at Pt, effectively reducing the adsorption of Cl⁻ and preventing the poisoning of the active site of Pt. As a result, Er₂O₃-Pt with half-wave potentials (E_1/2) of 0.85 and 0.67 V in alkaline seawater and pure seawater, respectively, was used as a cathodic catalyst in alkaline seawater-based ZABs to obtain a maximum power density of 184.6 mW·cm^-2 and remarkable stability in pure seawater.