Fabrication of Robust Covalent Organic Frameworks for Enhanced Visible-Light-Driven H₂ Evolution

Abstract

Developing photocatalysts capable of visible-light-driven water splitting to produce clean hydrogen (H2) is one of the premier challenges for solar energy conversion into clean and sustainable fuels. Inspired from the structure feature of photosystem I in nature, we have designed and synthesized a series of robust covalent organic frameworks (NKCOFs = Nankai University COFs) based on electric donor–acceptor moieties, in which the electron-donor group of pyrene can be used for harvesting light. Meanwhile, benzothiadiazole with different functional groups was introduced as an electron acceptor to tune the light-adsorption ability of COFs. Notably, the activity of NKCOF-108 for photochemical H2 evolution under visible light was among the highest in COFs without hybridization with other materials. We attribute the high hydrogen evolution rate of NKCOF-108 to its distinct structural features and wide visible-light-response range. The highly ordered layered structure ensures that sufficient active sites are accessible for H2 production, and the donor–acceptor design can promote the separation of photogenerated carriers. Our findings have provided an effective strategy to design photocatalysts for light-driven H2 evolution.