摘要
This study highlights a localized synergistic interaction among Pt trimers (PtT), oxygen vacancies (OV), and adjacent Pd atoms within a hierarchically structured catalyst. The catalyst, composed of cobalt oxide-supported palladium nanoparticles (NPs), is specifically optimized for the oxygen reduction reaction (ORR). With a remarkably low platinum loading of approximately 1 wt%, the catalyst (designated as CPP-1) demonstrates exceptional mass activities of 22,885.6 mA mgPt−1 at 0.85 V and 1685.6 mA mgPt−1 at 0.90 V versus the reversible hydrogen electrode (RHE) in an alkaline (0.1 M KOH) ORR environment. These performance metrics surpass those of commercial platinum catalysts (J.M.-Pt/C; 20 wt% Pt) by factors of 341.6 and 71.7, respectively. Additionally, the PtT enable a maximum power output of 353.2 mW cm−2 and a current density of 1024.1 mA cm−2 in an alkaline fuel cell (AFC) stack. In situ X-ray spectroscopy and electrochemical analysis reveal that PtT facilitates O₂ dissociation into chemisorbed oxygen (Oads), while Pd supports Oads diffusion, and oxygen vacancies (OV) drive the subsequent reduction steps. This coordinated mechanism ensures the simultaneous operation of all intermediate pathways and enables the regeneration of both active PtT sites and OV. Moreover, electron transfer from cobalt enhances the reaction kinetics of O₂ dissociation at PtT and the reduction of Oads at OV, further accelerating intermediate steps and significantly boosting the overall performance of CPP-1. Studies of CPP catalysts with Pt loadings exceeding 1 wt% indicate that ORR pathways remain confined to the localized PtPd interaction region, explaining the exceptional efficiency observed in CPP-1.
•Synergy between Pt trimers and adjacent metal sites enhances ORR activity of Pd nanoparticles on Co oxide.•This catalyst delivers exceptional mass activity, reaching 22,885.6 mA mgPt−1 at 0.85 V vs. RHE under alkaline conditions (0.1 M KOH).•PtT achieves a peak power density of 353.2 mW cm−2 and a current density of 1,024.1 mA cm−2 in an alkaline fuel cell stack.