Gd2O3-induced electronic modulation of Cu for efficient oxygen reduction in aluminum–air batteries

Abstract

A Gd2O3-modified copper-based composite catalyst (Gd2O3–Cu/C) was developed via solvothermal preassembly and high-temperature pyrolysis to overcome the sluggish oxygen reduction reaction (ORR) kinetics of aluminum–air batteries (AABs) and the limitations of Pt-based catalysts. The strong electronic interaction between Gd2O3 and Cu active sites efficiently regulates the electronic structure of the catalyst, reducing its work function and charge transfer resistance; this results in an increase in the valence band electron density, thus promoting a nearly four-electron ORR pathway and ultimately enhancing the overall ORR kinetics. The catalyst exhibited a half-wave potential of 0.82 V, a Tafel slope of 67 mV dec−1, a 90% current retention after 500 min, and outstanding methanol tolerance, demonstrating superior ORR kinetics and durability in alkaline electrolyte. When assembled into an AAB, the Gd2O3–Cu/C catalyst delivered an open-circuit potential of 1.521 V, a peak power density of 65.7 mW cm−2, and a specific capacity of 578.8 mAh g−1, outperforming the commercial Pt/C-based counterpart. Density functional theory calculations revealed that Gd-induced electronic modulation of Cu facilitates electron transfer from Gd2O3 to Cu, positively shifting the d-band center of Cu toward the Fermi level, optimizing the adsorption of ORR species, and thus enhancing the ORR performance. This work introduces a cost-effective and high-performance non-precious metal catalyst for ORR, with application in AABs for emergency power supplies.