A zeolitic imidazolate framework (ZIF-67) and graphitic carbon nitride (g-C3N4) composite based efficient electrocatalyst for overall water-splitting reaction

Abstract

Designing of non-noble, cost-effective, sustainable catalysts for water splitting is essential for hydrogen production. In this research work, ZIF-67, g-C₃N₄, and their composite (1, 3, 5, 6, 8 wt% g-C₃N₄@ZIF-67) are synthesized, and various techniques, XRD, FTIR, SEM, EDX and BET are used to examine their morphological properties for electrochemical water-splitting. The linkage of ZIF-67 with g-C₃N₄ synergistically improves the electrochemical kinetics. An appropriate integration of g-C₃N₄ in ZIF-67 MOF improves the charge transfer between the electrode and electrolyte and makes it a suitable option for electrochemical applications. In alkaline media, the composite of ZIF-67 MOF with g-C₃N₄ over a Ni-foam exhibits a superior catalyst activity for water splitting application. Significantly, the 3 wt% g-C₃N₄@ZIF67 composite material reveals remarkable results with low overpotential values of −176 mV@10 mA cm⁻², 152 mV@10 mA cm⁻² for HER and OER. The catalyst remained stable for 24 h without distortion. The 3 wt% composite also shows a commendable performance for overall water-splitting with a voltage yield of 1.34 v@10 mA cm⁻². The low contact angle (54.4°) proves the electrocatalyst's hydrophilic nature. The results of electrochemical water splitting illustrated that 3 wt% g-C₃N₄@ZIF-67 is an electrically conductive, stable, and hydrophilic-nature catalyst and is suggested to be a promising candidate for electrochemical water-splitting application.