Institute of Fundamental Technological Research

A promising approach to catalysis in various electrochemical applications is engineering of heterostructures with enhanced active sites and interfacial electron transfer processes. In this study, conductive NiCo2S4 was interfaced with layered MoS2 as bifunctional electrode material for asymmetric supercapacitors and hydrogen generation through water splitting. The creation of opposite charges within the heterostructure components facilitates the adsorption of OH− and H+ ions, thereby boosting the bifunctional potentials. The constructed NiCo2S4/MoS2 electrode showed excellent specific capacitance of 1488.9 F g−1 at 1.0 A g−1 current density and capacity retention of 93 % after 30-fold rise in current density. The asymmetric supercapacitor exhibits superior energy density of 63 Wh kg−1 at power density 7.56 kW kg−1 compared to similar electrode materials reported in literature. The hydrogen evolution performance of the electrode materials in alkaline media produced a low overpotential (79.95 mV at 10 mA cm−2) and small Tafel slope (59 mV dec−1) that are comparable to the state-of-the-art Pt/C. Density functional theory calculation reveals a fast electron transfer from NiCo2S4 to MoS2 leading to creation of positively charged surface and negatively charged surface at NiCo2S4 and MoS2 respectively that facilitate the adsorption of OH− and H+ ions. This study offered a promising high active and stable non platinum advanced electrode bifunctional catalyst for energy storage supercapacitor and energy conversion hydrogen generation.

Heterostructure, NiCo2S4, MoS2, Supercapacitor, HER