Construction of N-doped nickel sulfide nanosheets via PANI as a nitrogen donor for superior electrocatalytic water splitting

Abstract

It is indeed critical to develop efficient and low-cost catalysts for water splitting to meet the growing energy demand. The resultant N-NiS bifunctional water electrolysis catalyst was in situ produced on nickel foam by a straightforward hydrothermal encapsulation sulphuration process, and it demonstrated good electrocatalytic activity. A polyaniline (PANI) coating was used as a nitrogen donor. The use of thermally degraded PANI as a nitrogen source to dope nickel sulfide is a productive and environmentally responsible substitute for the use of conventional hazardous NH₃. The resulting change in the electronic structure of NiS due to nitrogen doping has improved its electrocatalytic performance, as evidenced by the alkaline electrolyzer made up of two pieces of the N-NiS electrode having a low cell voltage of just 1.57 V at 10 mA cm⁻². This is noteworthy as it surpasses the performance of Pt/C and RuO₂ electrode pairs currently available on the market. DFT calculations are conducted to understand the mechanism underlying the improved electrocatalytic performance and support the idea that the doping of N atoms changes the electronic structure of NiS and leads to the increase of vacancies around the Ni site, thereby facilitating the adsorption of intermediate products.