2D-Templated polysulfonated covalent organic framework as an active photo-electrocatalyst for hydrogen evolution

Covalent organic frameworks (COFs), with their customizable structural characteristics and use of earth-abundant semiconducting components, have emerged as a promising class of photocatalyst materials. In this study, we present a novel class of 2D-templated polysulfonated COF as efficient photo-electrocatalyst for the hydrogen evolution reaction (HER) in the presence of sacrificial agents. The study includes a design, synthesis, and photo-electrocatalytic activity of the 2D-templated polysulfonated COF which further supported by the theoretical modelling. By modulating the chemical functional group from oxygen to sulfur, we achieved a remarkable improvement in photocatalytic H₂ evolution rates, reaching 226.4 μmol h⁻¹ with excellent long-term stability. The functional group alteration at the photoactive COF sites effectively lowers the energy barrier for the formation of H intermediate species (H*) on the polymer surface and suppresses charge recombination. The role of sulfur and oxygen groups in influencing photocatalytic HER activity via electronic band structure alteration, carrier density and mobility enhancement is extensively investigated. This study not only provides key insights into the design principles of COF-based photo-electrocatalysts but also establishes a foundation for the rational development of highly efficient materials for sustainable hydrogen production.