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

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, Co 3 O 4 , Co 9 S 8 catalysts and their heterostructure Co 3 O 4 /Co 9 S 8 were synthesized and evaluated as water oxidation electrocatalysts. The characterization of Co 3 O 4 , Co 9 S 8 , and Co 3 O 4 /Co 9 S 8 electrocatalysts was performed using Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction techniques. The heterostructure Co 3 O 4 /Co 9 S 8 (1.46 V) exhibited water oxidation electrocatalysis at extremely low onset potential compared to Co 3 O 4 (1.58 V), and Co 9 S 8 (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 Co 3 O 4 /Co 9 S 8 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. • A novel Co 3 O 4 /Co 9 S 8 catalyst exhibited the excellent performance for water oxidation. • The Co 3 O 4 /Co 9 S 8 catalyst exhibits a favorable OER with 281 mV of overpotential. • A small Tafel slope of 37 mV dec −1 achieved for Co 3 O 4 /Co 9 S 8 electrocatalyst in alkaline media. • The Co 3 O 4 /Co 9 S 8 catalyst has low Tafel slope and overpotential than most state of art Co-based electrocatalysts.