Shape–Preserved CoFeNi–MOF/NF Exhibiting Superior Performance for Overall Water Splitting across Alkaline and Neutral Conditions

Abstract

This study reported a multi–functional Co0.45Fe0.45Ni0.9–MOF/NF catalyst for oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and overall water splitting, which was synthesized via a novel shape–preserving two–step hydrothermal method. The resulting bowknot flake structure on NF enhanced the exposure of active sites, fostering a superior electrocatalytic surface, and the synergistic effect between Co, Fe, and Ni enhanced the catalytic activity of the active site. In an alkaline environment, the catalyst exhibited impressive overpotentials of 244 mV and 287 mV at current densities of 50 mA cm−2 and 100 mA cm−2, respectively. Transitioning to a neutral environment, an overpotential of 505 mV at a current density of 10 mA cm−2 was achieved with the same catalyst, showing a superior property compared to similar catalysts. Furthermore, it was demonstrated that Co0.45Fe0.45Ni0.9–MOF/NF shows versatility as a bifunctional catalyst, excelling in both OER and HER, as well as overall water splitting. The innovative shape–preserving synthesis method presented in this study offers a facile method to develop an efficient electrocatalyst for OER under both alkaline and neutral conditions, which makes it a promising catalyst for hydrogen production by water splitting.