Electrodeposition of Cobalt Phosphosulfide Nanosheets on Carbon Fiber Paper as Efficient Electrocatalyst for Oxygen Evolution

Abstract

AbstractTo maximize the activity and durability of transition metal sulfides for water oxidation is still a great challenge. Herein, we developed a new cobalt phosphosulfide nanosheet on carbon fiber paper (CFP) substrate electrocatalyst (Co2−xSP/CFP) following a simple two‐step electrodeposition method. The cobalt sulfide nanosheets were first deposited onto CFP by cyclic voltammetry. Then, the surface structure and P/S ratio as well as the Co3+/Co2+ ratio of the phosphosulfide nanosheets were well tuned by regulating the cycling numbers of the phosphorous electrodeposition. Benefiting from the hierarchical structure, distinct phosphosulfide species, as well as a high Co3+ content derived from partial S substitution with P and nonstoichiometric phase, the as‐synthesized Co2−xSP/CFP exhibits remarkable activity with an overpotential of 279 mV at a current density of 10 mA cm−2, a low Tafel slope of 54 mV dec−1 and excellent long‐term stability towards OER (overpotential increase of only 4.7 % within 60 h). Structural analysis after stability test indicates that cobalt oxide/hydroxide species are formed on the surface, which contribute to the high performance and excellent durability for oxygen evolution. This provides a simple and facile approach to rationally design and synthesize transition metal phosphosulfides for advanced electrochemical application.