Combination of Theory and Experiment Achieving a Rational Design of Electrocatalysts for Hydrogen Evolution on the Hierarchically Mesoporous CoS2 Microsphere

We report that the combination of theoretical and experimental results has demonstrated that superior electrocatalytic performance can be achieved with the hierarchically mesoporous CoS2 microsphere terminated with CoS2 sheet arrays and highly exposed sulfur surfaces with an optimal hydrogen adsorption energy. The as-prepared mesoporous CoS2 microsphere shows a rather low overpotential of 90 mV at 10 mA cm(-2) and a small Tafel slope of 67.0 mV dec(-1), which is comparable to the precious 20 wt % Pt/C catalyst. Besides, two times higher electrochemical active surface area and excellent stability are obtained. The overall performance is superior to most of the previously reported catalysts. More importantly, we performed density functional theory calculations and have documented that a number of sulfur sites on the CoS2 surface exhibit high intrinsic hydrogen evolution activity and resistance to hydroxyl poisoning, leading to the superior catalytic performance and durability.