Fe, N co-doping and sulfur vacancy modification synergistically enhance oxygen evolution reaction and overall water splitting activity of CoS/Co3S4 heterojunction

The low electrical conductivity and inferior catalytic activity of cobalt sulfide are the primary factors limiting their application in electrocatalytic water splitting. In this work, CoS/Co 3 S 4 and Fe-CoS/Co 3 S 4 were initially synthesized via a hydrothermal method and subsequently annealed in an NH 3 atmosphere to obtain Fe, N-CoS/Co 3 S 4 . On the one hand, introducing the Fe element resulted in the modulation of the electronic structure and increased the electrochemically active surface area, promoting charge transfer efficiency and providing more active sites for the oxygen evolution reaction and overall water splitting reactions. On the other hand, doping N element introduced sulfur vacancies, enhancing the electrical conductivity and charge transfer efficiency. Consequently, Fe, N-CoS/Co 3 S 4 exhibits significantly higher oxygen evolution reaction (OER) and overall water splitting activity at a current density of 10 mA cm −2 compared to CoS/Co 3 S 4 , with overpotentials of 294 mV and 332 mV, respectively. Furthermore, this catalyst demonstrates excellent stability. The design of the catalyst structure provides theoretical support for researching Co-based catalysts in oxygen evolution reactions and overall water splitting.