Nanoporous Metal/Covalent Organic Framework-Based Electrocatalysts for Water Splitting

Abstract

In today's technological era, the increased consumption of fossil fuels has taken a severe toll on the environment. In response to this, researchers are actively pursuing to develop efficient methods such as water splitting to obtain cleaner fuel and mitigate the adverse effects on the environment. However, the reactions involved in this process are sluggish. In order to enhance the reaction rate, scientists have been exploring efficient catalysts with long-term durability and stability and the ability to facilitate the kinetics of the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Furthermore, due to the instability, high cost, and scarcity of noble-metal-based catalysts, researchers have shifted their focus to nanoporous-based metal–organic framework (MOF) and covalent organic framework (COF) catalysts, which not only offer enhanced stability but also contribute to increased conductivity, a crucial factor for materials used in water-splitting processes. Certain MOFs have been found to surpass platinum- and iridium-based catalysts in water catalysis. COFs also enhance OER and HER kinetics due to their large surface area, porosity, and excellent electrical conductivity, establishing them as valuable electrocatalysts in diverse applications. This Review provides a comprehensive investigation of electrocatalysts based on MOFs and COFs, encompassing their classification and synthetic pathways, with a special emphasis on their HER/OER performance. It also delves into intricate aspects such as structure–property correlations and nanostructure engineering, offering a comprehensive understanding of these materials in the context of electrocatalysis. Moreover, some of these catalysts exhibit notable efficiency for OER while others demonstrate proficiency for HER, which showcases their versatile electrocatalytic capabilities. Additionally, this Review sheds light on the future challenges confronting water splitting and engages in a discourse on potential solutions.