Enhanced electrochemical activity of Co3O4/Co9S8 heterostructure catalyst for water splitting

Abstract

The dearth of efficient, robust, and economical electrocatalysts for water oxidation is dubiously the key obstacle for renewable energy devices, so synthesis of efficient, and cost-effective metal-based water oxidation catalysts is vital. Herein, Co3O4, Co9S8 catalysts and their heterostructure Co3O4/Co9S8 were synthesized and evaluated as water oxidation electrocatalysts. The characterization of Co3O4, Co9S8, and Co3O4/Co9S8 electrocatalysts was performed using Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction techniques. The heterostructure Co3O4/Co9S8 (1.46 V) exhibited water oxidation electrocatalysis at extremely low onset potential compared to Co3O4 (1.58 V), and Co9S8 (1.48 V) catalysts. A 281 mV overpotential required to attain a current density of 50 mA cm−2 in alkaline solution (1 M KOH), outperforming most of Co-based benchmark electrocatalysts. Further, the Co3O4/Co9S8 heterojunction demonstrated catalytic activity with small Tafel slope of 37 mV dec−1. The finding of electrochemical studies involving controlled potential electrolysis and long-term stability are projected to steer the future advancement in constructing efficient, economical, stable, and earth-abundant metal-based water oxidation catalysts.