Nanospike Nickel-Iron Oxalate as an Efficient Electrocatalyst for the Oxygen Evolution Reaction

Obtaining hydrogen as a renewable fuel through water splitting is severely hindered by the energy-intensive oxygen evolution reaction (OER). Transition metal oxides based on low-cost and earth-abundant elements have been shown to provide high OER rivaling that of commercial IrO2, with nickel iron oxide/oxyhydroxide systems exhibiting some of the lowest reported overpotentials. Here, we report a nickel-iron oxalate material with a nanospike morphology synthesized via a simple and novel hydrothermal method, in which oxalate is generated in situ during material preparation under mild conditions. The as-synthesized nanostructured material displays high catalytic activity for OER, requiring a low overpotential of only 284 mV at a current density of 10 mA·cm−2, lower than that of its amorphous counterpart and commercial IrO2 (326 and 308 mV, respectively). This material also exhibits excellent long-term stability with retention of the nanospike morphology after several hours under OER conditions.