Ionic liquid polyoxometalate-enhanced Pd/N,P-codoped coal-based carbon fiber catalysts for formic acid electrooxidation

Abstract

Direct formic acid fuel cells have great application potential in the energy field, but their commercialization is hindered by the CO poisoning and low performance of Pd-based anode catalysts. In this study, novel composite catalysts composed of Pd, organic-inorganic hybrid imidazole ionic liquid polyoxometalates, and N,P-codoped coal-based carbon fibers with good dispersion and smaller Pd nanoparticles were synthesized successfully. Physical and electrochemical characterizations revealed that the as-prepared Pd-based composite catalysts have excellent CO poisoning resistance and enhanced electrocatalytic activity in formic acid electrooxidation. Notably, the CO oxidation onset potential of a catalyst modified by imidazole ionic liquid polyoxometalate with long alkyl chain was 0.1 V lower than that of the unmodified catalyst. The mass activity of the as-prepared Pd catalyst in formic acid oxidation was 754.1 mA mg−1Pd. It is expected that organic-inorganic hybrid polyoxometalates can be further applied to fuel cell catalysts.