Cobalt sulfide thin films for electrocatalytic oxygen evolution reaction and supercapacitor applications.

Nanocrystalline cobalt sulfide thin film electrodes have been deposited on stainless steel substrate using binder-free chemical bath deposition (CBD) method and electrochemical study is performed in 1 M KOH electrolyte. Linear sweep voltammetry (LSV) curve shows that cobalt sulfide thin film electrode requires 300 mV overpotential (ƞ) to reach the current density of 10 mA cm-2. Also, it exhibits Tafel slope of 57 mV decade-1 with stable catalytic activity over 14 h. Along with good electrocatalytic oxygen evolution performance, in supercapacitive study it shows specific capacitance of 252.39 F g-1 at a scan rate of 5 mV s-1. The stability test indicates that cobalt sulfide electrode is stable for 1000 cyclic voltammetry (CV) cycles.