Oxygen-vacancy-rich CoOx modified cubic platinum nanoparticles for highly efficient electrocatalytic ammonia oxidation reaction

Abstract

Direct ammonia fuel cells (DAFCs) operating at low temperatures represent a promising clean energy technology, generating only nitrogen (N2) and water (H2O) as byproducts. However, their widespread implementation is hindered by the kinetically sluggish six‑electron ammonia oxidation reaction (AOR) at the anode. Herein, we report a rational design of oxygen‑vacancy‑rich CoOx modified Pt nanoparticles via a combined crystal facet and defect engineering strategy. Electrochemical tests demonstrate that the optimized catalyst exhibits a mass activity of 165 A g-1 Pt, which is 47% higher than that of unmodified Pt cubic nanoparticles. Combined electrochemical and in-situ Fourier transform infrared (FTIR) spectroscopy analyses reveal that the enhanced performance stems primarily from the abundant oxygen vacancies within the CoOx. These vacancies facilitate the formation of adsorbed OH species (OHad), and induce strong metal support interactions (SMSI), thereby optimizing the reaction pathway and kinetics. This study provides valuable insights into the design of high performance AOR electrocatalysts through defect engineering.