Engineering of robust conjugated polymer-based aerogels via surface-initiated polycondensation towards sunlight-driven seawater desalination and uranium extraction.

The aerogels with low thermal conductivity and cross-linked 3D networks can be easily integrated with functional materials to maximize their functionalities, realizing diverse applications such as photothermal seawater desalination and photocatalytic uranium extraction. Sp²C-conjugated porous polymers (sp²C-CPPs) with robust and conjugated CC linkages are ideal photosensitizers for these applications, owing to their exceptional semiconducting properties as well as chemical stability. However, the limited processability and collectability of as-synthesized sp²C-CPP powders impede their extended applications. Herein, we report the preparation of robust sp²C-CPP (DHA-TMT and DBD-TMT) based aerogels via surface-initiated aldol polycondensation (SI-AP). The fully conjugated CC skeletons and electron-donating groups (-OH) endow the sp²C-CPP aerogels with excellent photothermal conversion efficiency (95.6%) and strong affinity for uranium adsorption. In particular, the DHA-TMT aerogel with hydrophilic porous channel exhibits a superb evaporation performance achieving ∼1.55 kg m^-2 h^-1 under AM 1.5 G while the fast mass transfer caused by photothermal conversion increases the uranium extraction capacity up to 1200 mg m^-2 in simulated seawater. Moreover, the sp²C-CPP aerogels demonstrate high stability under strong acid, base and brine solutions. This work shows a strategy for the preparation of uniform and high stability sp²C-CPP-based aerogels to simultaneously enhance their photothermal and photocatalytic performance.