Three-Dimensional Porous MnCo₂S₄ Microrugby Balls Supported on Carbon Cloth for Efficient Oxygen Evolution Reaction

The design and development of oxygen evolution electrocatalyst with stable structure and outstanding performance is of great significance for hydrogen production by water electrolysis. Inspired by the high stability of the self-supported catalyst and the synergistic effect of the bimetallic transition metal catalyst, MnCo₂S₄ microrugby balls were successfully prepared on carbon cloth by a two-step hydrothermal method in this work. The prepared MnCo₂S₄/CC exhibits remarkable electrochemical performance due to the stable self-supporting design and lavish porous structure, as well as the high inherent electrical conductivity of sulphide. The overpotential of MnCo₂S₄/CC is only 180 mV at the current density of 10 mA cm⁻², which is 161 mV lower than that of MnCo₂O₄/CC (341 mV). The Tafel slope of MnCo₂S₄/CC is 145.7 mV dec⁻¹, which is less than that of MnCo₂O₄/CC (157.5 mV dec⁻¹). The OER performance of MnCo₂S₄/CC is significantly improved due to its high electrochemically active surface area and conductivity. Density functional theory (DFT) calculations show that MnCo₂S₄/CC has a higher electron density than MnCo₂O₄/CC, which indicates that it has better conductivity. These results indicate that it is a feasible method to optimize the performance of the electrocatalysts by combining the large electrochemical surface area provided by the porous structure of the self-supported catalyst and the large electrical conductivity of the sulphide.