Solar-driven interfacial evaporation technology is a
novel and
efficient desalination process that helps alleviate the global shortage
of freshwater resources. We developed a Janus evaporator assembled
from cotton hydrogel, hydrophilic polyester fabric (PF), and Hydrophobic
Wood (PW). By doping graphene oxide and TiO2 as light-absorbing
materials within the hydrogel, we achieved a high absorptivity of
over 90% across the entire solar spectrum. The hydrophilically modified
PF, combined with the PW substrate, provided robust water transport
and reduced thermal losses. Subsequent optical path simulations using
TracePro74 software verified that the sawtooth light-trapping design
of the wood substrate increased multiple light reflections and absorption
(compared to a flat structure), enhancing light absorption capabilities.
The sawtooth interface also enlarged the evaporation area, further
boosting evaporation performance. The cleverly designed evaporator
exhibited an evaporation rate of 1.722 kg m–2 h–1 and an efficiency of 83.1% under 1 sun irradiation.
Additionally, after applying polydimethylsiloxane to the single surface
of the photothermal hydrogel for low surface energy treatment, the
resulting Janus structure demonstrated asymmetric wettability that
prevented salt ions from accumulating on the irradiated interface.
After 8 h of continuous evaporation in saline water (10 wt %), only
slight salt crystallization occurred at the edges. The evaporator
maintained long-term stability during a 15 day cyclic test, and the
produced freshwater fully met the relevant drinking water standards.
The components of the evaporator are characterized by simple fabrication,
low cost, and eco-friendliness, offering significant application potential
in the global context of energy conservation and emission reduction
initiatives.