Bifunctional two-dimensional metal organic frameworks for oxygen reaction and water splitting

Electrocatalytic hydrogen evolution process (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) are three common reactions found in energy conversion devices. Nevertheless, the slow reaction rates of the HER, OER, and ORR, as well as their dependence on electrocatalysts containing noble metals such as platinum (Pt), iridium (Ir), and ruthenium (Ru), impede their widespread usage in commercial settings. Therefore, there is a strong need for the creation of cost-effective, high-performing, durable, and easily expandable electrocatalysts. However, achieving this goal is extremely challenging. Bifunctional electrocatalysts are capable of concurrently catalyzing both HER/OER and OER/ORR. In recent years, there has been a significant amount of great research focusing on the development of bifunctional 2D MOF electrocatalysts which are designed to facilitate overall water splitting and oxygen reactions. The current study presents recent advancement in the applications of bifunctional 2D MOF electrocatalysts for OER and ORR, HER and OER. Prior to highlighting the evaluating techniques for bifunctional 2D MOF for water splitting; and protocol for bifunctional 2D MOF electrolysis (involving for water splitting and oxygen reaction), different synthetic strategies, structural distinction, overview of characterization techniques and the relationship between the MOF structures and their conductivities were discussed. In addition, detailed electrocatalytic performance for bifunctional 2D MOFs toward OER/ORR and HER/OER followed by the strategies for enhancing bifunctionalities in 2D MOFs were discussed. The concluding section focused on identifying knowledge gaps, associated shortcomings, and strengths, as well as important perspectives and ideas for improving the bifunctional 2D MOFs for oxygen reaction and overall water splitting in line with realistic industrial expectations. This review provides the scientific community with a comprehensive understanding of the current research focus and the importance of developing more efficient and environmental-friendly bifunctional 2D MOFs for clean energy. This is crucial in addressing the challenges of reducing greenhouse gas emissions and mitigating the global energy shortage.