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

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-CoO_x) on the CC were regulated, and CoP_x nanoparticles with small particle size and uniform distribution were obtained. The optimized CoP_x-based catalyst with 40 cycles of ALD-O₃ treatment (CoP_x/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-CoP_x/CC), although the CoP_x loading of CoP_x/40-CC is lower than that of Imp-CoP_x/CC. The results indicate that the enhanced activity benefits from the small particle size and the uniform CoP_x distribution, which promote the electron-transfer and mass transport kinetics of the methanol electro-oxidation process.