Harnessing bimetallic spinel cobaltite with hematite for electrocatalytic overall water splitting: A comprehensive...

Electrocatalytic water splitting presents a potential avenue for hydrogen production, paving the path towards a green and sustainable economy. This study focuses on the fabrication of hematite and transition-metal cobaltite (NiCo₂O₄@Fe₂O₃) based bifunctional catalyst for overall water splitting. The carefully engineered NiCo₂O₄ nanospheres and α-Fe₂O₃ nanoneedles exhibit enhanced performance, highlighting the critical role of morphology in determining the availability of active sites and surface area, which in turn leads to improved catalytic activity. In this study, the optimized NiCo₂O₄@Fe₂O₃ nanocomposite showing the current density of 50 mA/cm² at 264 mV overpotential with a Tafel slope of 67 mV/dec and 21.9 mF/cm² of C_dl value with corresponding electrochemical active surface area (ECSA) of 438 cm² for oxygen evolution reaction (OER). Similarly, in hydrogen evolution reaction (HER), 201 mV of overpotential is required to attain 50 mA/cm² current density. The observed Tafel, C_dl and ECSA were 43 mV/dec, 21.1 mF/cm², and 422 cm², respectively. In the light of its excellent bifunctional activity full-cell studies were carried out to ensure the efficiency and robustness in overall water splitting, which exhibits the cell potential of 1.73 V to attain 50 mA/cm² current density. Theoretical investigations supported these findings by revealing potential electron transfer mechanisms and structural stability.