Constructing high-performance supercapacitors and electrochemical water splitting electrode materials through core–shell structured Co9S8@Ni(OH)2 nanosheets†
Abstract
The development of advanced electrode materials featuring high specific capacitance and superior electrocatalytic efficiency is pivotal for the advancement of energy storage and conversion technologies. This research introduces a Co9S8@Ni(OH)2 core–shell structured electrode material, synthesized via the hydrothermal method, which exhibits outstanding electrochemical properties. The material demonstrates a remarkable specific capacitance of 844.8 C g−1 at a current density of 1 A g−1, and the constructed supercapacitor achieves an energy density of 60.76 W h kg−1 at a substantial power density of 35 280 W kg−1, maintaining 85.3% of its initial capacity after 15 000 cycles. Moreover, the material exhibits exceptional hydrogen evolution reaction (HER) performance, with an overpotential of only 92.7 mV and a Tafel slope of 147.86 mV dec−1 at 10 mA cm−2. The oxygen evolution reaction (OER) performance is equally commendable, evidenced by an overpotential of 163.3 mV and a Tafel slope of 50.27 mV dec−1 at the same current density. These results underscore the Co9S8@Ni(OH)2 core–shell structured material as a promising candidate for enhancing supercapacitor and electrochemical water splitting technologies. Density functional theory (DFT) analysis further elucidates the pivotal role of Ni(OH)2 in augmenting the electronic structure and catalytic activity of the Co9S8 catalyst, indicating optimized electronic properties and reduced hydrogen adsorption free energy, thereby signifying its enhanced activity and efficiency in electrocatalytic water splitting.