One-Step Synthesis of Nickel Sulfides and Their Electrocatalytic Activities for Hydrogen Evolution Reaction: A Case Study of Crystalline h-NiS and o-Ni9S8 Nanoparticles

Electrocatalytic materials play a crucial role in the development of technologies for hydrogen production (hydrogen evolution reaction) from renewable and sustainable energy resources. Among these materials, nickel sulfides are promising catalysts due to their activity, stability, and cost-effectiveness. However, while the performance of nickel sulfides is linearly correlated to the crystalline structure, synthesis of single crystalline phases of nickel sulfides with controlled morphology is not trivial. In the face of this challenge, we report a simple and selective method to synthesize different phases and morphologies of nickel sulfide with superior electrocatalytic activities, by combining microwave energy and a solvothermal method.