Embedding the intermetallic Pt5Ce alloy in mesopores through Pt–C coordination layer interactions as a stable electrocatalyst for the oxygen reduction reaction†

Abstract

Platinum dissolution is one of the primary factors affecting the stability of Pt-based catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). It is a significant challenge to prevent the dissolution of Pt and enhance the durability of Pt-based catalysts. In this study, we employed a one-step rapid Joule thermal shock method to fabricate a stable ORR catalyst with embedded Pt₅Ce alloy (E-Pt₅Ce). The strong catalyst-support interactions between the Pt–C layer suppress particle agglomeration and Ostwald ripening, and its steric hindrance effect reduces the electronic density at Pt sites, decreasing the adsorption energy of Pt with oxygen-containing intermediates and preventing Pt dissolution. The Pt–C layer also increases the accessibility of active sites, boosting the ORR activity. In acidic media, E-Pt₅Ce shows a mass activity (MA) and specific activity (SA) of 2.86 A mg_Pt⁻¹ and 2.03 mA cm⁻², outperforming the commercial Pt/C by factors of approximately 15 and 5, respectively. When used as a cathode catalyst for a PEMFC, the MA at 0.90 V is almost twice the DOE 2025 target. After stability testing, there is no prominent loss in catalytic activity. Density functional theory calculations confirm that the Pt–C coordination bonds also serve as reactive sites. This work uncovers the mechanism of action of the Pt–C coordination layer, which plays a crucial role in the preparation and performance of ORR catalysts.