Composite hydrogel-based photothermal self-pumping system with salt and bacteria resistance for super-efficient solar-powered water evaporation

Synergistically increasing the solar adsorption/conversion, regulating the water transfer and activation as well as resisting the fouling to enhance the solar-powered interfacial water evaporation performance remains an urgent challenge. Herein, a smart 3D porous photothermal composite hydrogel MoS2@GH, where the antibacterial porous molybdenum disulfide (MoS2) nanoflowers were intercalated between graphene (MoS2@GH) via a simple chemical reduction, was prepared. This cooperated with a controllable self-pumping system of salt concentration differences and liquid level height differences-driven capillary water transfer/transpiration (CHTS) for solar steam generator. In this generator, the hierarchically porous hydrogel not only contributed the light trapping to enhance solar absorption but also generated more dispersed hotspots to access and activate water. Simultaneously, the CHTS system regulated an appropriate water replenishment without direct immersion into bulk water to match the evaporation of hydrogel. As a result, this system can achieve a super-efficient water evaporation rate of 3.2 kg m−2 h−1 under 0.9 sun, and can also delay the salting out fouling and resist the bacterial biofouling. These together with the good thermal and chemical stability of the pure inorganic hydrogel entrust an efficient water desalination, paving a robust way for sustainable clean water production. [Display omitted] •Salt concentration−/liquid level height differences were used for self-pumping system.•MoS2-intercalated graphene was prepared as porous photothermal composite hydrogel.•Enhanced light trapping and dispersed hotspots contributed an excellent evaporator.•A super-efficient water evaporation rate of 3.2 kg m−2 h−1 was achieved.•The system can delay the salting out fouling and resist the bacterial biofouling.