Recent Advances in Electrocatalysis of Oxygen Evolution Reaction using Noble‐Metal, Transition‐Metal, and Carbon‐Based Materials

Abstract A considerable concern in exploring clean, efficient, and renewable energy resources to effectively replace fossil fuels and to combat the environmental problems and energy scarcities for a sustainable future has been observed. In this context, hydrogen is a clean, renewable, energetically efficient fuel with infinite potential for the future, which can generate a large amount of energy through the electrocatalytic splitting of earth‐abundant water resources. Noble metals, owing to their extraordinary efficiency and stability, are state‐of‐the‐art catalysts for the oxygen evolution reaction (OER) process. However, their scarcity and high cost hamper their commercialization. To replace these expensive noble‐metal‐based materials, researchers are extensively working on the development of cost effective, stable, conductive, and efficient non‐noble metal based materials such as transition metal oxides, borides, nitrides, sulfides, phosphides, selenides, perovskites oxides, and layered double hydroxides, where the incorporation of heteroatoms improves the electrocatalytic activity by modifying the electronic structure and enhances the conductivity and stability. In the case of transition‐metal based metal organic frameworks (MOFs) and MOF‐derived materials, the unique structure of MOFs with a high surface area and porosity, as well as rich redox chemistry of transition metals, leads to excellent response towards the OER process. Moreover, direct utilization of carbonaceous materials or making their composites with transition metals not only enhances the conductivity due to their conductive nature but also promotes stability by strongly binding with the electrocatalyst. Owing to the presence of functional groups on the surface or through different interactions, they provide multiple paths for facile electron and ion transport due to the sheet/network like structure, which help in the fine dispersion of electrocatalyst due to high surface area, prevent agglomeration, and in turn results in improved electrocatalytic activity. Besides these advances, a) there is still a need for a thorough understanding of reaction mechanism via in situ spectroscopic techniques to further optimize the composition and design of electrocatalyst to get desired results, b) the stability of the materials should be further enhanced to practically utilize synthesized material under harsh conditions without degradation, and c) the utilization of these optimized OER catalysts in a solar cell to consume solar energy (renewable energy source), remains a key requirement of the modern era.