Nd-Based Multitransition Metal Oxide/Nitrogen-Doped Carbon Composite Electrocatalyst for High Performance Zinc-Air...

Developing cost-effective bifunctional oxygen electrocatalysts with synergistically high activity and stability is critical for rechargeable zinc-air batteries (ZABs). Herein, a Nd-based multitransition metal (Fe/Co/Ni/Mn/Cr) oxide/nitrogen-doped carbon composite is designed via a precipitation-melamine-assisted calcination strategy integrating a crystalline Nd₂O₃ framework, electroactive NdNiO₃/NiCrO₄ phases, and a conductive N-doped carbon network. It exhibits outstanding electrocatalytic performance: an oxygen reduction reaction half-wave potential of 0.781 V (vs. reversible hydrogen electrode (RHE)), an oxygen evolution reaction overpotential of 1.552 V (vs. RHE) at 10 mA·cm^-2 and a narrow potential gap (ΔE) of 0.771 V. The assembled ZABs deliver an open-circuit voltage of ~1.50 V, a peak power density of ~76.5 mW·cm^-2, a specific capacity of ~711 mAh·g^-1 and exceptional cycling stability over 780 h (~2340 cycles). Postcycling characterization (X-ray photoelectron spectroscopy, scanning electron microscopy) reveals good structural integrity with only minor particle fusion and carbon oxidation, corroborating the stability observed in electrochemical tests. The synergistic interplay among components optimizes intermediate adsorption and electron transfer, while degradation is attributed to a mixed 2e^-/4e^- ORR pathway, active phase agglomeration, and carbon support oxidation. This work not only provides a promising nonprecious metal catalyst for advanced ZABs cathodes but also offers deep insights into the structure-activity-stability relationships governing bifunctional oxygen electrocatalysis.