Pyrrole-Derived Covalent Organic Frameworks: A Promising Platform for Efficient Bifunctional Electrocatalytic Water Splitting

The development of metal-free bifunctional electrocatalysts for hydrogen and oxygen evolution reactions (HER and OER) is of great significance for the sustainable development of clean energy, yet it has rarely been demonstrated. The incorporation of heteroatoms into covalent organic frameworks (COFs) introduces tailored electronic properties and well-defined electroactive sites, resulting in an exceptional electrocatalytic performance. Herein, a pyrrole-based bifunctional COF was designed and synthesized, featuring exceptional stability, enlarged surface areas, and accelerated mass transport. This precise structural modulation enables us to gain insight into the local microenvironment of active sites, such as heteroatom doping, methyl group incorporation, and the length of the linker, in relation to electrocatalytic activity. The most effective bifunctional electrocatalyst, NUST-38, exhibits overpotentials of 182 and 303 mV for HER and OER, respectively (in 1 M KOH) at a current density of 10 mA cm–2, ranking among the top-performing metal-free bifunctional electrocatalysts. Moreover, investigations have proved that NUST-38 retains its performance even after 10,000 CV cycles. This work validates the enormous potential of metal-free electrocatalysts for HER and the OER, providing valuable insights for the development of efficient metal-free COFs as organic electrocatalyst.