In-situ deposition to synthesize photothermal materials for enhanced solar-driven interfacial evaporation and gradient materials for electricity generation

In our contemporary society, addressing the increasingly pressing global resource shortage, particularly the scarcity of vital water resources and energy, is critical for human survival. This paper presents a strategy that integrates PAA grafting, ion exchange, and in-situ chemical reactions to synthesize photothermal materials for enhanced solar-driven interfacial evaporation and gradient materials for electricity generation, respectively. The obtained photothermal material demonstrates exceptional light absorption and photothermal conversion performance. By employing a unique combination of unidirectional flow and suspension mode for water evaporation, remarkable evaporation rates are achieved, with all samples exceeding 2.03 kg m-2h−1. The hybrid mode is also applied to saltwater treatment, where it is found that the evaporation rate is not significantly affected, regardless of the salt concentration. No change in the evaporation rate is observed even after 12 h of continuous treatment with 10 % brine, indicating the robustness and stable performance of the evaporative materials. For the synthesized gradient materials, the flowing fluid can establish a potential difference at both ends of the gradient fabric. The magnitude of open circuit voltage and short circuit current can be controlled by adjusting the measurement distance, the deposited nanoparticles with different polarity and the amount of charge carried. We acquire a maximum output of 209.7 mV using the gradient Cu-S/PAA-cotton fabric, which can be connected in series to power small electronic devices like a digital watch. This research not only advances the design and practical application of high-performance solar evaporators but also illuminates a novel pathway for developing electricity-generating materials.