Benzotriazole-based ionic COFs embedded in biologic aerogels for stable photocatalytic seawater splitting

Abstract

Solar-driven photocatalytic seawater splitting, although highly desirable, is challenging because the complex composition of real seawater causes problems such as corrosion, active site blockage, and non-radiative recombination of charge carriers in photocatalysts. Here, we designed a benzotriazole-based ionic covalent organic framework (COF) using a post-modification method for photocatalytic seawater splitting. To enable its practical applications, the ionic COF was engineered into a freestanding aerogel with nanocellulose. Benefiting from the intramolecular electric field generated by the ionic groups and donor–acceptor configuration within the COF skeleton, the hybrid aerogel achieved a high hydrogen evolution rate of 87 mmol m⁻² h⁻¹, with a remarkable apparent quantum yield of 11.6% at 420 nm. Besides, the photothermal effect of the COF facilitates the continuous reflow of pure water onto the aerogel surface, affording pronounced long-term photocatalytic stability for several weeks. Additionally, the porosity and large specific surface area of the aerogel further contribute to light trapping, heat accumulation, water affinity and ion repulsion. Together, these tailorable characteristics position the ionic COF as a highly promising platform for photocatalytic seawater splitting.