Enhancing NiS performance: Na-doping for advanced photocatalytic and electrocatalytic applications

Abstract

Alkali metal doping is a new and promising approach to enhance the photo/electrocatalytic activity of NiS-based catalyst systems. This work investigates the impact of sodium on the structural, electronic, and catalytic properties of NiS. Comprehensive characterization techniques demonstrate that Na-doping causes significant changes in the NiS lattice and surface chemistry translating into a larger bandgap than NiS. Photocatalytic experiments demonstrate 98.5% degradation of 2,4-DCP under visible light, attributing it to improved light absorption and charge separation by Na–NiS nanoparticles. The effect of pH and pK_a on the degradation of 2,4-DCP has also been studied and reported. Additionally, electrochemical measurements of Na–NiS indicate overpotentials of 336 mV towards hydrogen evolution reaction (HER) and 350 mV towards oxygen evolution reaction (OER). The material's overall water splitting is found to be 2.61 V at a current density of 10 mA cm⁻². The results highlight the potential of Na–NiS as a versatile catalyst for environmental remediation and clean energy applications, paving the way for further exploration and optimization of doped transition metal sulfides.