Nanoparticles of Pyrochlore-Type AgSbO 3 Electrocatalysts for the Oxygen Evolution Reaction and Oxygen Reduction Reaction

The urgent need for efficient and cost-effective bifunctional electrocatalysts for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) remains a major challenge in developing oxygen-based electrochemical devices. This study focuses on the pyrochlore-type AgSbO 3 material, which suffers from relatively poor intrinsic conductivity, limiting the rapid transport of electrons within the catalyst and at the catalyst-reactant interface. However, the incorporation of Ag, due to its excellent conductivity, appropriate cost-performance ratio, and inherent high activity, effectively enhances the OER/ORR catalytic kinetics. A nanoheterostructured AgSbO 3 –Ag composite was successfully fabricated via hydrothermal synthesis, wherein nanoscale metallic Ag particles were uniformly anchored on the surface of nano-AgSbO 3 matrices, forming unique nanoheterointerfaces. In contrast to the microsized AgSbO 3 prepared by conventional solid-state sintering, this material constructs an optimized triple-phase interface through synergistic effects, significantly enhancing electron conduction efficiency and reactant mass transfer rates, while also exposing numerous highly active catalytic sites, thereby substantially improving the overall electrocatalytic performance. In electrochemical tests, the material demonstrated excellent catalytic activity and stability in both acidic and alkaline environments: in 0.5 M H 2 SO 4 and 1 M KOH, it required overpotentials of only 237 mV and 119 mV, respectively, to achieve a current density of 10 mA cm –2 . Furthermore, it maintains stability for over 40 h in both acidic and alkaline solutions at a current density of 10 mA cm –2 . The catalyst exhibited a half-wave potential of 0.78 V for ORR, with only a 10 mV decrease after 2,000 cycles of cyclic voltammetry (CV) testing, further confirming its outstanding durability. In addition, during the assembly and testing of zinc-air batteries, the hydrothermal AgSbO 3 –Ag maintained excellent charge–discharge cycle performance for over 90 h, achieving a power density as high as 180 mW cm –2 . It is evident that Ag, as the active site, enhances the electrochemical performance. This work is bound to provide guidance for the development of efficient OER/ORR catalysts.