Secondary reduction strategy synthesis of Pt–Co nanoparticle catalysts towards boosting the activity of proton exchange membrane fuel cells

Abstract

Based on the volcanic relationship between catalytic activity and key adsorption energies, Pt–Co alloy materials have been widely studied as cathode oxygen reduction reaction (ORR) catalysts in proton exchange membrane fuel cells (PEMFCs) due to their higher active surface area and adjustable D-band energy levels compared to Pt/C. However, how to balance the alloying degree and ORR performance of Pt–Co catalyst remains a great challenge. Herein, we first synthesized a well-dispersed Pt/Co/C precursor by using a mild dimethylamine borane (DMAB) as the reducing agent. The precursor was calcined at high temperature under H2/Ar mixed gas by a secondary reduction strategy to obtain an ordered Pt3Co intermetallic compound nanoparticle catalyst with a high degree of alloying. The optimization of electronic structure due to Pt–Co alloying and the strong metal-carrier interaction ensure the high kinetic activity of the cell membrane electrode. Additionally, the high degree of graphitization increases the electrical conductivity during the reaction. As a result, the activity and stability of the catalyst were significantly improved, with a half-wave potential as high as 0.87 V, which decreased by only 20 mV after 10000 potential cycles. Single-cell tests further validate the high intrinsic activity of the ordered Pt3Co catalyst with mass activity up to 0.67 A mgpt−1, exceeding the United States Department of Energy (US DOE) standard (0.44 A mgpt−1), and a rated power of 5.93 W mgpt−1.