Oxidized Ti Single Atoms and Co₃O₄ with Abundant Oxygen Vacancies Collaborating with Adjacent Pd Sites for an Efficient and Stable Oxygen Reduction Reaction

The current study addresses these key issues by providing the ensemble sites and creating oxygen vacancies in the oxidized Ti-single atoms. Here we report a novel heterogeneous catalyst comprising oxidized Ti-single atoms uniformly coated on the cobalt-oxide-supported Pd nanoparticles (denoted as CP@Ti-1), where the oxygen vacancies are introduced in oxidized Ti-single atoms as well as cobalt-oxide support. As-developed CP@Ti-1 catalyst demonstrates remarkable ORR activity with a mass activity (MA) of 9,725 mAmg_Ti ^-1 at 0.85 V vs RHE and 1,244 mAmg_Ti ^-1 at 0.90 V vs RHE in alkaline conditions. These values mark significant improvements over the commercial J.M.-Pt/C catalyst, outperforming it by 145- and 50-fold, respectively. Additionally, the CP@Ti-1 catalyst shows exceptional durability, maintaining 100% of its initial performance after 20, 000 cycles of accelerated degradation test (ADT). In-situ X-ray absorption spectroscopy (XAS) analysis reveals that the catalyst design promotes synergistic interactions between oxygen vacancies in Ti/Co atoms and adjacent Pd domains, facilitating key reactions in ORR such as oxygen splitting and hydroxide ion formation, respectively, enhancing overall catalytic efficiency. These insights promise significant advancements in both scientific research and industrial applications of ORR catalysis.