Hydrogen evolution reaction in acidic and basic medium on robust cobalt sulphide electrocatalyst

Huge research interest has been paid to produce the robust, efficient and large area electrodes based on non-noble electrocatalyst as an alternative of Pt. Herein, we report the facile synthesis of cobalt sulphide (CoS) based electrocatalyst with polycrystalline structure and non-uniform morphology. Also, flexible, robust, large area and bio-degradable electrodes on paper are prepared. Owing to different metal electronic states like Co2+ and Co3+, CoS electrocatalyst show rapid hydrogen evolution reaction. CoS based electrodes shows HER activity with overpotential of 284 mV in alkaline medium and 198 mV in acidic medium. In alkaline medium, electrodes follow sluggish Volmer reaction while in acidic, dynamic Heyrovsky-Volmer reaction is step determining reac-tion step. Paper based electrodes functionalised by CoS electrocatalyst advocate the futuristic development of non-noble electrodes for clean energy generation via electrocatalytic HER.