Synthesis of Near-Infrared-Absorbing Superhydrophilic Conjugated Porous Polymer via Postsynthetic Modification for Efficient Solar Steam Generation

The utilization of solar energy as an alternative to fossil fuels is important for a sustainable society. Recently, various photothermal materials that are capable of steam generation by using sunlight have emerged to produce clean water. However, challenges such as low absorption of light, low hydrophilicity, low porosity, and poor stability of the photothermal materials limit their application. In this context, conjugated porous polymers (CPPs) can be potential candidates for solar steam generation owing to their high porosity, low density, structural tunability, and thermal stability. Herein, a superhydrophilic CPP, PTD-CPP, was synthesized through postsynthetic modification (PSM) of superhydrophobic perylene-based CPP (P-CPP). The donor–acceptor-based rigid π-system of PTD-CPP exhibits strong visible-to-near-infrared absorption from 400 to 800 nm, making it effective for solar energy absorption. As a result, PTD-CPP demonstrates a water evaporation rate as high as 3.02 kg m–2 h–1, compared to that of P-CPP (2.64 kg m–2 h–1). Moreover, PTD-CPP exhibits excellent solar-to-vapor conversion efficiency (87.21%), underscoring the importance of broad light absorption, porosity, and superhydrophilicity for enhanced water transport.