Metal Organic Framework Catalyst of Mesoporous K-doped NiCo₂O₄ for Improved Oxygen Evolution

The water splitting reaction is a key process for the conversion and storage of clean and renewable energy, but requires a highly efficient non-precious metal electrocatalyst to reduce wide overpotentials for oxygen evolution reaction (OER) or hydrogen evolution reaction (HER). In particular, many efforts have been applied to explore high-efficiency OER catalyst because the OER has a higher kinetic barrier than the HER. Here, we have developed a novel K-doped NiCo₂O₄ (NCO) catalyst derived from the metal organic framework structure of Prussian Blue analogue (PBA) to demonstrate a high-performance OER electrode. The material is prepared with a simple hydrothermal synthesis method using the potassium (K) precursor present in the PBA. The K-doping in the NCO catalyst shows a high conductivity not only to increase the number of active oxygen vacancies but also change their intrinsic properties such as binding energy. The cyclic voltammetry (CV) scan of the K-doped NCO catalyst showed a low overpotential value of 0.292 V at a current density of 10 mA cm^-2 and a Tafel value of 49.9 mV dec^-1, outperforming a commercial OER catalyst (Iridium). The synthesized K-doped NCO can be utilized as high performance electrode materials for metal-oxide batteries and supercapacitors.