🤝 Collaborative Paper

Local collaboration between oxygen vacancy, palladium and platinum trimer triggers exceptional performance in the alkaline fuel cell

Chemical Engineering Journal, 522 (2025) 167605 | DOI: 10.1016/j.cej.2025.167605

Authors：Dinesh Bhalothia, Che Yan, Yawei Wu, Jui-Cheng Kao, Yu-Chieh Lo, Haolin Li, Nozomu Hiraoka, Hirofumi Ishii, Yen-Fa Liao, Sheng Dai, Chen-Hao Wang, Alice Hu, Jyh-Pin Chou, Po-Chun Chen, and Tsan-Yao Chen

📄 Abstract

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 1,685.6 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 1,024.1 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.

🔬 Five Core Findings

Ultra-high mass activity: CPP-1 achieves 22,885.6 mA mgPt⁻¹ at 0.85 V and 1,685.6 mA mgPt⁻¹ at 0.90 V, representing 341.6× and 71.7× improvement over commercial Pt/C (20 wt%) with only 1 wt% Pt loading.

Exceptional fuel cell output: Maximum power density of 353.2 mW cm⁻² and current density of 1,024.1 mA cm⁻² achieved in AFC stack.

Tri-phase localized synergy: PtT dissociates O₂ to Oads, Pd facilitates Oads diffusion, and OV drives subsequent reduction steps—forming a complete ORR pathway.

Active site regeneration: PtT and OV can be simultaneously regenerated, maintaining catalytic activity and stability during long-term operation.

Electronic effect of Co: Electron transfer from cobalt oxide enhances O₂ dissociation kinetics on PtT and Oads reduction kinetics on OV, further accelerating the reaction.

📊 Key Figures

Key Figure 1: Electrochemical performance of CPP-1 catalyst, caption embedded in image.

Key Figure 2: In-situ XAS analysis results, caption embedded in image.