Organic photothermal cocrystal with high stability for efficient solar-driven water evaporation

Abstract

Solar-driven water evaporation is a promising way to cope with global water shortage. Photothermal conversion materials are prerequisites that ensure efficient water evaporation. The cocrystal strategy provides a shortcut to synthesizing photothermal materials. However, the photothermal cocrystal systems reported currently are scarce due to unclear design ideas. It is urgent to develop novel stable and highly efficient photothermal conversion cocrystals. In this work, we obtained a novel photothermal conversion cocrystal of TMBZ-TCNB by a simple solution method. Intramolecular charge transfer interactions within the cocrystal result in a wide absorption (from the UV to NIR region) and high-efficiency nonradiative process. As a result, the photothermal efficiency of TMBZ-TCNB has been demonstrated to be 59.46% under 808 nm laser radiation. Then a TMBZ-TCNB-PU interfacial evaporator was fabricated, which exhibited a good water evaporation efficiency of 63.49% under 1 kW m⁻² radiation. In particular, TMBZ-TCNB exhibits outstanding irradiation/thermal/chemical stability, which is favorable to sustain long-term evaporation in the complex environment of water evaporation. This work provides a novel photothermal conversion material, which promotes the development of photothermal cocrystals in solar-driven water evaporation.