Fe and Mo Co-Modulated Coral-like Nickel Pyrophosphate in situ Derived from Nickel-Foam for Oxygen Evolution

A highly active catalyst for the oxygen evolution reaction (OER) is critical to achieve high efficiency in hydrogen generation from water splitting. Direct conversion of nickel foam (NF) into nickel-based catalysts has attracted intensive interest due to the tight interaction of the catalysts to the substrate surface. However, the catalytic performances are still far below expectation because of the problems of low catalyst amount, thin catalyst layer, and small active area caused by the limitations of the synthesis method. Herein, we develop a Fe³⁺ -induced synthesis strategy to transform the NF surface into a thicker catalyst layer. In addition to the excellent conductivity and high stability, the as-prepared FeMo-Ni₂ P₂ O₇ /NF catalysts expose more active sites and facilitate mass transfer due to their thicker catalyst layer and highly dense coral-like micro-nano structure. Furthermore, the Mo, Fe co-modulation optimizes the adsorption free energies of the OER intermediates, boosting catalytic activities. Its catalytic activity is among the highest, and it exhibits a small Tafel slope of 34.71 mV dec^-1 and a low overpotential of 161 mV for delivering a current density of 100 mA cm^-2 compared to reported Ni-based catalysts. The present strategy can be further used in the design of other catalysts for energy storage and conversion.