Highly dispersed CoPx nanoparticles supported on carbon cloth for the enhanced catalytic performance of methanol electro-oxidation

Abstract

Direct methanol fuel cell (DMFC) is a potential commercial fuel cell technology that is presently hindered by the expensive noble metal materials of the anode. Developing a method to obtain a uniformly dispersed metal phosphide catalyst with narrow size distribution is still a challenge. In this work, cobalt oxide was deposited on carbon cloth (CC) through atomic layer deposition (ALD), then cobalt phosphide was obtained after the phosphorization process. By changing the number of ALD-based ozone pulses (ALD-O3) for CC, the nucleation and growth modes of cobalt oxide (ALD-CoOx) on the CC were regulated, and CoPx nanoparticles with small particle size and uniform distribution were obtained. The optimized CoPx-based catalyst with 40 cycles of ALD-O3 treatment (CoPx/40-CC) exhibits excellent activity (153 mA/cm2) toward methanol electrocatalytic oxidation reaction in the alkaline solution, which is higher than the catalyst prepared by impregnation (Imp-CoPx/CC), although the CoPx loading of CoPx/40-CC is lower than that of Imp-CoPx/CC. The results indicate that the enhanced activity benefits from the small particle size and the uniform CoPx distribution, which promote the electron-transfer and mass transport kinetics of the methanol electro-oxidation process.