Carbon supported bimetallic Pd-Co catalysts for alkaline sulfide oxidation in direct alkaline sulfide fuel cell

In this study, carbon supported Pd and Pd-Co alloys were synthesized and investigated as anode catalysts for the practical application of a promising sulfide-fed fuel cell, named direct alkaline sulfide fuel cell (DASFC). Physical and electrochemical properties of the Pd/C and Pd-Co/C catalysts were evaluated using X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive X-ray (EDX), inductively coupled plasma optical emission spectroscopy (ICP-OES), cyclic voltammetry (CV), linear sweep voltammetry (LSV), I-V analysis and electrochemical impedance spectroscopy (EIS). Among all the Pd-based catalysts tested, Pd8Co2/C showed the highest sulfide oxidation activity in terms of the lowest onset potential and the highest current density, mass activity, and specific activity at −0.2 V (vs. Ag/AgCl). The maximum power density of DASFC with Pd8Co2/C anode catalyst was 46.82 mW cm−2 at 70 °C, which is 26% higher than that with Pd/C. It is speculated that the incorporation of Co into Pd facilitated the adsorption of OHads at a lower potential, and Pd8Co2/C provided the optimal coverage of OHads that played a catalytic role and thus led to the highest performance.