NiCoFe-Based Metal-Organic Framework Nanosheets on Ni Foam for High-Efficiency Electrochemical Water Splitting

We report the synthesis of a ternary transition metal-based metal-organic framework (MOF) material, NiCoFe-MIL53, using a one-step solvothermal method with nickel foam (NF) as a conductive substrate. The resulting composite, NiCoFe-MIL53/NF, exhibits high activity and excellent stability for electrocatalytic water splitting. It is found that incorporation of cobalt not only enhances the electrical conductivity and intrinsic catalytic activity of the catalyst, but also influences the morphology of the synthesized products. This morphological transformation increases the contact area between the electrocatalyst and the electrolyte solution, leading to an improved electrocatalytic performance. Notably, the optimized composition of NiCoFe-MIL53 with a proper mass ratio of Ni/Co/Fe requires the lowest overpotential of 206 mV at 10 mA cm^{− 2} and a Tafel slope of 21.09 mV dec^{− 1} for oxygen evolution reaction in alkaline aqueous solution (1 M KOH). Moreover, this composite also shows excellent electrocatalytic performance for both cathodic and anodic reactions during overall water splitting, achieving a current density of 10 mA cm^{− 2} at an applied potential of 1.61 V. This work highlights the potential of noble-metal-free MOF-based materials as dual-functional catalysts for highly active and stable electrocatalytic water splitting.