Metal-Organic Framework Derived Nanostructured Bifunctional Electrocatalysts for Water Splitting

With continuously increasing energy requirements, electrochemical water splitting is a solution to generate hydrogen as a carbon-free fuel for future energy demands. Water splitting reaction is made up of two half electrochemical reactions - hydrogen evolution (HER) and oxygen evolution (OER). The principal components of these electrochemical reactions are electrode materials, which are currently facing challenges in performance improvement, thus developing advanced electrode materials or electrocatalysts is essential. Metal-organic frameworks (MOFs) are crystalline porous materials that have recently exhibited great potential as precursor for designing excellent water splitting electrocatalysts. These MOF-derived materials are not attractive just because of high-performance in electrocatalysis but also owing to their fascinating nanostructures, which are difficult to achieve by other synthetic methods. Search for well-shaped nanostructured materials using MOF as a precursor for water splitting have attracted the attention in recent time and is a rapidly growing research area. This review summarizes the progress towards MOF-derived electrocatalysts for water electrolysis especially focusing on nanostructure engineering, structure-property correlations, and their bifunctional HER/OER performances. Performance of these bifunctional catalysts in two-electrode electrolyzers are also discussed. Finally, existing obstacles and the future prospects of MOF-derived bifunctional water splitting electrocatalysts are elaborated.