Bifunctional Fabric with Photothermal Effect and Photocatalysis for Highly Efficient Clean Water Generation

Fresh water scarcity has become a global challenge owing to the limited fresh water resource and the increasing water pollution. Solar-driven water evaporation with the interfacial heat localization is a promising technology to mitigate the fresh water scarcity. Here, we propose a bifunctional cotton fabric with both photothermal and photocatalytic properties by in situ polymerization of pyrrole (Py) on the cotton and subsequent deposition of titanium dioxide (TiO2) nanoparticles. The morphology of the polypyrrole (PPy) can be adjusted, and fibrous PPy with a high hydrophilicity and a higher surface area was obtained on the cotton fibers in the presence of polydopamine (PDA). The TiO2–PDA/PPy/cotton showed a solar evaporation rate of 1.55 kg m–2 h–1 under 1 sun illumination, which is higher than that for most previously reported evaporation systems. Besides the efficient solar vapor generation, the TiO2–PDA/PPy/cotton also presented an excellent photocatalysis with a ∼96% degradation of methyl orange (MO) under simulated solar irradiation over 3 h. The PDA/PPy structure can enhance the photocatalytic activity of TiO2 by promoting the separation of photogenerated electron–hole pairs and decreasing charge recombination. This bifunctional fabric will provide a new approach for addressing the issue of fresh water scarcity.