Electronic Modulation of Pd/C by Simultaneous Doping of Cu and Co Tendering a Highly Durable and Methanol-Tolerant Oxygen Reduction Electrocatalyst

Abstract

Pd-based electrocatalysts are considered as suitable replacement for Pt-based ones owing to the similar electronic structure of Pd, relatively low cost, and superior catalytic performance. The activity and utilization efficiency of Pd in electrochemical reactions can be increased by alloying with transition metals, like Cu and Co. Herein, we report the synthesis of a homogeneously embedded Pd2CuCo alloy in the carbon matrix. Compared with the benchmark Pt/C, the as-synthesized Pd alloy electrocatalyst exhibited an improved limiting current density (Jm; −5.65 mA cm–2), a smaller Tafel slope (58.7 mV dec–1), and a comparable onset potential (Eonset; 0.91 V vs RHE). Comparatively, the optimized Pd2CuCo showed a current retention of ∼96% after a 6 h stability test and only a 4 mV loss in the half-wave potential (E1/2) after 10,000 redox cycles, while Pt/C showed a current retention of 72.5% and a loss of 5 mV in E1/2. Meanwhile, the Pd2CuCo alloy electrocatalyst also demonstrated excellent methanol tolerance compared to benchmark Pt/C. In addition, the electrocatalyst showed higher activity and long-term stability toward the formic acid oxidation reaction than Pd/C, signifying the potential for wide applicability.