A dual-functional metalloporphyrin-fluorenone covalent organic framework for solar hydrogen and oxygen production

Abstract

Developing efficient dual-functional photocatalysts for the solar-driven conversion of H₂O into H₂ and O₂ is a challenging yet promising approach to achieve carbon-free fuel production. Herein, we present a newly developed covalent organic framework (COF), integrated with cobalt porphyrin (Co-TP) and fluorenone (FO), as an efficient dual-functional photocatalyst. The Co-TPFO-COF exhibits structural advantages in photocatalysis due to its highly crystalline structure with high surface area and porosity. Additionally, the Co-TP unit serves not only as an electron donor enabling intramolecular electron transport to the FO unit for H₂ production, but also an oxidation-active moiety for efficient O₂ evolution. An O₂ yield rate of 2399 μmol g⁻¹ h⁻¹ was achieved with an apparent quantum efficiency of 1.06%, while the H₂ production rate reached 1015 μmol g⁻¹ h⁻¹. The performances can be ascribed to the synergy between directional charge transfer, decreased O₂ evolution barriers and enhanced H⁺ adsorption. This study paves the way for the development of dual-functional COF photocatalysts for solar-to-fuel conversion.