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Developing highly electroactive and stable electrocatalysts with selective adsorption of the intermediates is essential to enhance the electrochemical water splitting efficiency. Porphyrin-based covalent organic polymers (COPs) offer a promising platform due to their multidimensional frameworks, π-conjugated structure, tunable porosity, and intrinsic redox activity. These features endow them with excellent electrocatalytic activity as compared to their monomeric counterparts. This review compiles and analyzes the recent advancements in building porphyrin-based COPs and their composites for electrocatalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Special emphasis is placed on incorporating different metals in the porphyrin and their linkage with a variety of organic ligands having electron-withdrawing moieties on them. The multiple dimensionalities and synergy between metals and π-conjugated systems contribute to the excellent electrocatalytic efficiency of porphyrin COPs for water electrolysis. The metalation of the porphyrin units provides the electroactive active sites contributing to efficient charge transfer kinetics of HER and OER, low resistances to charge transfer, low overpotentials, and high electrochemical surface area. This work gives a comprehensive analysis of the structure-activity relationship of porphyrin COPs and also describes a comparative analysis of the electrocatalytic activities of the porphyrin COPs in alkaline and acidic media. Finally, the current challenges and futuristic insights have been provided for designing porphyrin-based COPs to enhance their electrocatalytic performance for water splitting. • Porphyrin-based COPs as electrocatalysts for HER, OER, and bifunctional water electrolysis. • Understanding the technologies, mechanistic insight of HER, and OER. • Highly promising porphyrin COPs-based composites with sulfides, CNTs, rGO, & GDY for HER & OER. • Lower overpotential, low Tafel slopes, high surface area, and low charge transfer resistance. • An insight into the challenges and the prospects for designing Porphyrin-based COPs.
Arshad et al. (Wed,) studied this question.