Mo2C/CNTs supported Pd nanoparticles for highly efficient catalyst towards formic acid electrooxidation

Abstract

A novel method to self-assemble PMo₁₂ on CNTs followed by a thermal treatment under hydrogen was developed for a highly dispersed Mo₂C/CNTs hybrid and was further used to support Pd towards formic acid oxidation. TEM examinations show that the CNTs are uniformly covered by Mo₂C particles with a diameter of 1–2 nm. The Pd–Mo₂C/CNTs catalyst exhibits a more negative onset potential (−0.16 V) than Pd/CNTs (−0.13 V) and Pd/C (−0.12 V), showing the highest intrinsic electrocatalytic activity, while its peak current density (845 mA mg⁻¹ Pd) is ∼1.6 and 2.3 times higher than that of Pd/CNTs (534 mA mg⁻¹ Pd) and Pd/C (371 mA mg⁻¹ Pd), indicating the highest electroactive surface area. The Pd–Mo₂C/CNTs catalyst also demonstrates excellent long-term stability, which is likely to have contributions from the incorporation of Mo₂C that significantly enhances the dehydrogenation path while lessening the dehydration path, resulting in the poisoning reduction of the Pd catalysts. It is reasonably proposed that the assembled Mo₂C acts not only as a support to enhance the catalyst uniformity, but also as a co-catalyst to directly promote both electrocatalytic activity and stability. This work provides an efficient method to prepare Mo₂C/CNTs as a promising support towards oxidation of small organic molecules in fuel cells.