CuNCo3-Xvx Antiperovskite As a High Performance Catalyst for Oxygen Evolution Reaction
Authors: Zhang Jiaxi , Du Li , Cui Zhiming 
Published: February 2020

Oxygen evolution reaction (OER) has drawn particular attention due to its important role for various energy generation and storage application, such as water splitting, rechargeable metal-air batteries and regenerative fuel cells. However, the intrinsically sluggish kinetic caused by multi proton-couple electron transfer steps, makes the OER inefficient on these applications. To promote the overall energy storage and generative efficiency, it is indispensable to develop highly efficient electrocatalyst for OER. Up to now, the noble-metal oxides (e.g. IrO2 and RuO2) are still considered as the best electrocatalysts for OER. Nevertheless, the high cost and scarcity of the involved precious metal have greatly limited their applications. Therefore, it urgently requires to seek the highly efficient OER catalysts that are cost-effective and earth-abundant. In the past decades, the perovskite oxides (ABO3, where A is rare or alkaline earth metal element and B is transition metal element) have been considered as an alternative OER catalyst for their low cost and intrinsically desirable OER activities. These oxides possess sufficient combination between different transition metal, which enables the highly synergic effect for their electrocatalysis. Also, the A site or B site can be partially substituted by other transition metal. This structural flexibility can arise the enhancement of the activity and stability of the perovskite oxides. However, the perovskite-based OER catalysts usually suffer poor conductivity at the applied temperature. To solve this problem, a widely used strategy is to combine metal oxides with high-surface-area carbon supports. It’s notable that metal oxide/carbon hybrid catalysts are unstable, especially under the condition of oxygen evolution reaction, because the oxidation of carbon occurs at low potentials (equilibrium potential of 0.207 V vs. the reversible hydrogen electrode (RHE). Transition metal nitrides are very attractive as robust supports and electrocatalysts because they have a number of desirable properties such as high electrical conductivity. Some antiperovskite nitride such as InNNi3 have been considered as the superconductive materials. More interestingly, the antiperovskite nitrides (ANM3, A and M represent different transition metal, respectively) share the similar perovskite structure with the perovskite oxides. Moreover, the perovskite structure of antiperovskite nitrides may enable the ANM3 to achieve structural flexibility as the corresponding effects have been verified by the previously reported materials (e.g. CdNCo3-zNiz (0  z 3) and Cd1−xInxNNi3 (0  x  0.2)). The tunable structure of the ANCo3 can offer much potential for the optimization of its electrocatalytic activity.
Herein, we report an antiperovskite-based CuNCo3-xVx (0  x < 1) nitride as a high-performance OER catalyst exhibiting favorable electrocatalytic activity and stability. The experimental results reveal that the CuNCo3 exhibits highly intrinsic OER performance compared to Co4N. And the structural flexibility of the antiperovskite CuNCo3 also has been verified by the partially substituting the Co sites with V. The derived CuNCo2.4V0.6 can achieve an impressive enhancement with an overpotential of merely 242 mV to reach the current density of 10 mA cm-2. The time-dependent potential measurement and zinc-air batteries test also suggested its superior durability compared to Ir/C catalyst. Density of states (DOS) indicates the partial substitution of Co by V results in the negative shift of the d band center near the Fermi level for CuNCo3, which would weaken the interaction between the adsorbates and the OER catalyst and facilitate the OER process.