Electrothermal-assisted all-weather solar steam generator based on hydrogel implantation strategy

Using solar energy to treat sewage is a feasible scheme to alleviate the shortage of water resources and reduce carbon emissions. However, the fluctuation of sunlight intensity poses a great challenge to the stability of the treatment process, which hinders its application in the actual water treatment scene. Herein, based on the adhesion of hydrogel, an electrothermal-assisted all-weather solar steam generator with sandwich structure was synthesized through hydrogel implantation strategy, in which polyacrylamide hydrogel with thermal grease-modified heating wires was implanted as the middle heat conduction layer, the photothermal evaporation layer as the upper layer and the waste heat evaporation layer as the bottom layer. The electrothermal assisted solar evaporator (EASE) perfectly achieves the superposition of photothermal and electrothermal effects, and can achieve high interfacial water evaporation performance under extremely low auxiliary working voltage. Applying a low voltage of 2 V to both ends of the evaporator can achieve a high evaporation rate of 4.58 kg m−2h−1 under 1 solar irradiation, which is similar to the sum of the evaporation rate under only 1 solar illumination (2.22 kg m−2h−1) and a 2 V voltage input (2.26 kg m−2h−1). More interestingly, the suitable thickness of the hydrogel layer not only ensures the transfer of heat between layers, but also weakens the heat loss caused by the water flow effect. The implantation strategy ensures the stability of the water structure and inhibits the hydrogen reaction of electrolytic water in the electrothermal process. This work provides an important theoretical and practical reference for the preparation of all-weather solar interface water purification equipment.