Black Silver-Decorated liquid metal nanofillers coupled with Glycerol-Modified hydrogel composites for high efficiency solar steam generation and thermoelectric conversion

Abstract

Solar-driven interfacial evaporation (SDIE) holds great potential in alleviating global freshwater scarcity, which requires the design of efficient energy conversion devices. Herein, a quadruply engineered hydrogel-based evaporator is developed based on multipath regulation of the four key processes involved in SDIE, i.e., heat generation, energy utilization, water transportation, and evaporation. Surface-tailored liquid metal nanoparticles (EGaIn@Ag NPs) with a high photothermal conversion efficiency (PCE) of 30.4 % serve as the nanofiller to produce heat efficiently. Vertically aligned microchannels are constructed in the poly(vinyl alcohol) (PVA) hydrogel through directional freezing to accelerate water transportation. Glycerol is introduced to the PVA matrix to synergistically a) prevent heat loss from the interface to bulk water, and b) modulate the bonding state of water in the hydrogel to reduce the vaporization enthalpy. Such an elaborate design achieves a rather high evaporation rate of 3.26 kg m−2h−1 under 1 sun illumination. The hydrogel evaporator (EGaIn@Ag/PVAG) is applicable in treating real seawater and dye-contaminated sewages, showing favorable desalination durability and self-cleaning property. The synergistic design also imparts the hydrogel with thermoelectric power generation capabilities. This work offers a new insight into the synergistic design of SDIE devices, which is expected to inspire innovations in solar energy conversion and utilization.