A paper-based reduced graphene oxide composite membrane is integrated with a floating silicone-based thermal insulation layer for high-efficiency, fast-response solar-driven interfacial evaporation under one-sun illumination.
The
plasmonic heating effect of noble nanoparticles has recently received
tremendous attention for various important applications. Herein, we
report the utilization of interfacial plasmonic heating-assisted evaporation
for efficient and facile solar-thermal energy harvest. An airlaid
paper-supported gold nanoparticle thin film was placed at the thermal
energy conversion region within a sealed chamber to convert solar
energy into thermal energy. The generated thermal energy instantly
vaporizes the water underneath into hot vapors that quickly diffuse
to the thermal energy release region of the chamber to condense into
liquids and release the collected thermal energy. The condensed water
automatically flows back to the thermal energy conversion region under
the capillary force from the hydrophilic copper mesh. Such an approach
simultaneously realizes efficient solar-to-thermal energy conversion
and rapid transportation of converted thermal energy to target application
terminals. Compared to conventional external photothermal conversion
design, the solar-thermal harvesting device driven by the internal
plasmonic heating effect has reduced the overall thermal resistance
by more than 50% and has demonstrated more than 25% improvement of
solar water heating efficiency.
Superheated solar steam generation above 100 °C is critical for many important applications such as sterilization but is challenging to achieve under natural fluctuating low-flux solar illumination and often requires pressurization and the usage of expensive optical concentrators. Herein, we demonstrate generation of superheated steam under ambient pressure and low-flux solar illumination by integrating a recently emerged interfacial evaporation design into a solar vacuum tube. Within the tube, the water vapor, which is generated by a high-efficiency localized heating-based evaporator, is further heated by a heat exchanger into superheated steam without pressurization. The steam generator has shown tunable steam temperature from 102 to 165 °C and solar-to-steam conversion efficiency from 26 to 49% under 1 sun illumination. Owing to the minimized heat loss from the solar vacuum tube and the interfacial evaporation design, it enables stable generation of steam above 121 °C under ambient fluctuating solar illumination with an averaged solar flux of ∼600 W/m 2 . Effective sterilization is verified using both the Geobacillus stearothermophilus biological indicator and Escherichia coli bacteria, making portable solar steam sterilization and other steam-related applications feasible under ambient solar illumination.
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