Quaternization-Induced Metalloporphyrin-Based Covalent Organic Polymer/MWCNT Hybrid for Bifunctional Water Splitting

Covalent organic polymers (COPs) have attracted considerable attention as electrocatalysts because of their tunable structures, high porosity, and abundant functional sites, yet their practical application is often limited by poor electrical conductivity. Herein, conductive metalloporphyrin-based COP hybrids were synthesized through a quaternization-induced polymerization strategy in the presence of multi-walled carbon nanotubes (MWCNTs). The resultant FeTPyPCOP@MWCNTs and NiTPyPCOP@MWCNTs integrate metalloporphyrin coordination sites, a porous polymer framework, and a conductive carbon network within a single architecture. A direct comparison between the two materials reveals that FeTPyPCOP@MWCNTs exhibit superior electrocatalytic activity toward water splitting, highlighting the important influence of the coordinated metal center. FeTPyPCOP@MWCNTs requires overpotentials of only 117 mV for the hydrogen evolution reaction (HER) and 241 mV for the oxygen evolution reaction (OER) at 10 mA cm-2. In a two-electrode electrolyzer, it delivers 10 mA cm-2 at a cell voltage of 1.56 V, together with excellent durability and near-quantitative Faradaic efficiency. This work demonstrates that combining metalloporphyrin coordination environments with conductive polymer/carbon architectures is an effective strategy for developing efficient bifunctional electrocatalysts for overall water splitting.