Facile Construction of Metal Phosphides (MP, M = Co, Ni, Fe, and Cu) Wrapped in Three-Dimensional N,P-Codoped Carbon Skeleton toward Highly Efficient Hydrogen Evolution Catalysis and Lithium-Ion Storage.

Abstract

Transition metal phosphides (TMPs) have been demonstrated for prospective applications in electrocatalytic reaction and energy conversion owing to their specialties of catalytic activity and superhigh theoretical capacity. Herein, a facile and robust strategy for confining phosphides in a three-dimensional N,P-codoped carbon skeleton was achieved through a simple evaporation method. After calcination treatment, metal phosphide nanoparticles (MP, M = Co, Ni, Fe, and Cu) were successfully encapsulated in an interconnected N,P-codoped carbon network, which not only endowed high electrical conductivity and electrochemical stability but also provided more active sites and ion diffusion channels. As-prepared CoP@N,P-C exhibited satisfactory hydrogen evolution reaction activity, displaying lower overpotential of 140 and 197 mV at 10.0 mA cm-2 in 0.5 M H2SO4 and 1.0 M KOH, respectively. Moreover, CoP@N,P-C also delivered satisfactory lithium-ion storage properties. A higher specific capacity of 604.9 mAh g-1 was retained after 1000 cycles at 0.5 A g-1, one of the best reported performances of CoP-based anode materials. This work highlights a facile pathway to encapsulate metal phosphides in a conductive carbon skeleton, which is suitable for scaled-up production of bifunctional composites for efficient energy storage and conversion.