In-situ growth of nanostructured nickel sulphides on nickel foam platform for boosting the electrocatalytic activity of overall water splitting

Abstract

Electrocatalysts for overall water spitting that are inexpensive and extremely effective are essential and highly needed in the field of sustainable energy. Herein, in-situ synthesis of nanostructured nickel sulphides (NiS) thin films with needle and sheet-like morphologies was achieved via a simple hydrothermal processing of nickel foam (NF) in the presence of thiourea (TU). The effect of reaction time and calcination temperatures were explored for developing an efficient water electrolyser. The results showed that, the hydrothermal treatment of NF for four hours displayed a sheet-like morphology with overpotential (η) of 223 mV for hydrogen evolution reaction (HER) to deliver 50 mA/cm2. While, the oxygen evolution reaction (OER) was carried out at η50 = 128 mV for nickel sulphide nanoneedles that formed after hydrothermal treatment for eight hours followed by calcination for two-hours at 200 °C. It was found, the chemical compositions of NiS nanostructures were the key factors affect their electrochemical performance for OER and HER. Integration of the boosted NiS platforms will offer inexpensive, sustainable and easy to scale-up water electrolyser with a perfect overall water splitting at 1.63 V to deliver 50 mA/cm2 in 1.0 M KOH. This work inspires the design of NiS -based platforms with improved or new functionalities for energy conversion and catalysis applications.