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Finding nonprecious metal based highly active and durable bifunctional electrocatalysts for overall water-splitting is essential for the development of various renewable energy storage and conversion technologies. Herein, we report the synthesis of cobalt iron layered double hydroxide (Co1−δFeδ LDH) and g-carbon nitride composite (Co1−δFeδ LDH/g-CNx) for alkaline water electrolysis. The thin Co1−δFeδ LDH nanosheets are successfully impregnated on graphitic carbon nitride surface by one pot co-precipitation method at ambient temperature. The optimal composite, Co0.4Fe0.6 LDH/g-CNx exhibited superior OER activity in 1 M KOH electrolyte with a small overpotential of 0.28 V for 10 mA cm–2, low Tafel slope of 29 mV/dec, 100% faradic efficiency, and high TOF of 0.25 s–1 which is superior to commercial (comm) IrO2. Furthermore, the Co0.4Fe0.6 LDH/g-CNx composite also exhibited remarkable HER activity in alkaline media and its HER activity is slightly lower than that of comm Pt/C at low overpotential but it outperforms Pt/C at high overpotential. The catalyst demonstrated its long-term durability and higher stability for HER and OER under alkaline environment. This Co0.4Fe0.6 LDH/g-CNx catalyst can serve as both cathode and anode for overall water-splitting and required the small potential of 1.61 V to achieve a current density of 10 mA cm–2. The superior electrocatalytic activities of the Co0.4Fe0.6 LDH/g-CNx composite are due to the high electrochemical surface area (ECSA), easy access of abundant active sites, and easy mass transport owing to 2D sheet morphology of the composite.
Bhowmik et al. (Thu,) studied this question.