Carbon-Supported Mn-Doped Intermetallic Ptco as an Efficient Nanocatalyst for the Oxygen Reduction Reaction

Abstract

To reduce the usage of Pt, accelerate the kinetics of oxygen reduction reaction (ORR) and enhance the stability of catalysts, active and stable low-Pt catalysts need to be developed. Herein, carbon-supported Mn-doped intermetallic PtCo (Mn-PtCo/C), synthesized through liquid-phase hydride reduction followed by high-temperature hydrogen reduction, as ORR catalysts for proton exchange membrane fuel cells are reported for the first time. The increased electrochemical surface area due to small particle size, and optimized d-band center due to ordered intermetallic structure and electronic structure of the Mn-PtCo/C tuned by Mn doping contribute to impressive ORR performance. The Mn-Pt9Co-1.5/C catalyst manifests a larger mass activity of 0.574 A mg-1Pt and specific activity of 0.854 mA cm-2Pt, which are 2.3- and 2.8‐fold enhancements compared with the commercial Pt/C (0.248 A mg-1Pt and 0.302 mA cm-2Pt), an improved ORR activity. The as-synthesized catalyst also exhibits enhanced structural stability after 10,000 cycles, with much higher initial and post-decay mass and specific activities than the contrast, as well as the intermetallic structure remains intact. The Mn-Pt9Co-1.5/C-based electrode is further evaluated in an H2-air single-cell system, showing a greater power density of 0.876 ± 0.009 W cm-2 than the Pt3Co/C-based electrode (0.617 ± 0.031 W cm-2).

Keywords: Electrocatalyst, Pt-based ternary alloys, Ordered intermetallic compound, Manganese doping, Oxygen reduction reaction