Oxygen Electrocatalysis by Transition Metal Nitrides: History, Current Trends and Future Prospects

The oxygen reduction and evolution reactions are considered the bottleneck in many electrochemical devices, i. e., fuel cells, water electrolyzers, and metal-air batteries. The continuous focus has been on inventing and exploring cost-effective and robust electrocatalysts. Few developed non-precious metal/metal-free materials, in fact, outperformed state-of-the-art catalysts during the half-cell study. However, most of these materials show limited activity during the full cell demonstration, restricting their deployment in commercial energy devices. In this direction, transition metal nitrides (TMNs) have emerged as a potential alternative with peculiar electronic properties and the ease of tuning their intrinsic as well as extrinsic properties. High hardness, refractory nature, d-band modulation ability and comparatively lower energy for the nitride formation are the other motivations to explore their effectiveness in oxygen electrocatalysis. Considering this, the minireview attempts first to present the properties of catalytic interest, followed by the most viable synthesis approaches in nanoengineering of the TMNs. Next, we provide key trends toward catalytic property modulation for oxygen electrocatalysis, the role of TMNs as potential catalytic support, followed by the effect of TMNs & PRIME; in situ autoxidation on the performance. Finally, we state the current limitations of TMNs toward oxygen electrocatalysis, followed by our vision for further advancements.