Intercalation of g-C3N4/Ag2S heterostructure on boronized Ni-MOF for enhanced water splitting and energy storage applications

Abstract

The increasing global demand for energy conversion and storage technologies including water electrolysis, fuel cells, batteries & supercapacitors depend critically on the performance of their electrode components. Metal Organic Frameworks (MOFs), particularly Nickel Zeolite Imidazole Frameworks (Ni-ZIF) have drawn significant attention due to their greater electrocatalytic performance. Still, their restricted active sites & stability hinder their broader implementation in alkaline/saline water electrolysis & supercapacitor applications. Here, we are reporting the intercalation of heterostructure consisting of silver sulfide (Ag₂S)/graphitic carbon nitride (g-C₃N₄) on Boronized Ni-ZIF (B:NZ) for empowered alkaline/saline water splitting and supercapacitor applications. These heterostructure addition over Boronized Ni-ZIF demonstrated minimal overpotentials for the oxygen evolution reaction (OER) (324 mV at 10.0 mA cm^-2) and the hydrogen evolution reaction (HER) (78 mV at 10.0 mA cm^-2) in alkaline medium (1 M KOH). The observed improvement in activity is ascribed to the decreased charge transfer resistance (R_ct) & the augmented electrochemical active surface area (ECSA). Furthermore, Ag₂S/g-C₃N₄/Boronized Ni-ZIF exhibited high specific capacitances of 1076.6 F/g and areal capacitance of 2584 F/cm² at 0.50 A g^-1 in supercapacitor applications. The incorporation of the g-C₃N₄ layer has enhanced the surface area and roughness facilitating stronger adhesion between hybrid layers which in turn resulted in prolonged stability exceeding 20 h in water splitting and 86 % retention in supercapacitor application.