The impact of surface chemistry on the performance of localized solar-driven evaporation system

Abstract

This report investigates the influence of surface chemistry (or wettability) on the evaporation performance of free-standing double-layered thin film on the surface of water. Such newly developed evaporation system is composed of top plasmonic light-to-heat conversion layer and bottom porous supporting layer. Under solar light illumination, the induced plasmonic heat will be localized within the film. By modulating the wettability of such evaporation system through the control of surface chemistry, the evaporation rates are differentiated between hydrophilized and hydrophobized anodic aluminum oxide membrane-based double layered thin films. Additionally, this work demonstrated that the evaporation rate mainly depends on the wettability of bottom supporting layer rather than that of top light-to-heat conversion layer. The findings in this study not only elucidate the role of surface chemistry of each layer of such double-layered evaporation system, but also provide additional design guidelines for such localized evaporation system in applications including desalination, distillation and power generation.

Reusable reduced graphene oxide based double-layer system modified by polyethylenimine for solar steam generation

“…These methods are summed up in the following three aspects: i) Nanoscale particles can be assembled into macro-systems for recycling and reusing [26e28]; ii) Free floating system can reduce heat loss because the vapor bubbles generated on a water-air interface do not need to travel through the bulk solution, then reducing the heat transfer to water [21,29,30]; iii) Simple preparation process can realize highly efficient solar steam generation in complex environment [31].…”

Steam generation in a nanoparticle-based solar receiver

“…Conventionally steam is produced by the combustion of fossil fuels or direct heating from electricity, which is environmentally unfriendly. Employing solar energy, an abundant, clean and renewable energy source, for steam production is a rapidly developing area [5][6][7][8]. Currently solar-based steam production (i.e., either solar trough or solar tower systems) is based on heating a bulk fluid to its boiling temperature under high optical concentrations.…”

Steam generation under one sun enabled by a floating structure with thermal concentration

“…However, to reach 100°C for steam generation, a solar flux of 10 kW/m 2 , 10 times the normal sun (1000 W/m 2 ), was needed by optical concentration. Several other groups have looked into the role of surface chemistry in aiding water delivery and thermal insulation of the bottom layer, 20 incorporating plasmonic or carbon-based absorption layers, [29][30][31][32][33] and using other cheap and abundant materials. 34,35 These studies have achieved relatively high evaporation efficiencies, but relied on optical concentration to boost the evaporation temperatures and achieve such efficiencies.…”

“…[8][9][10][11][12] Plasmonic nanoparticles with absorption and scattering cross-sections exceeding their geometrical cross-sections have been recently developed and applied for direct solar steam generation [13][14][15][16][17][18][19][20][21][22][23][24] , but they typically require optical concentration of 10-1000x for steam generation. However, optical concentrators are expensive ($200/m 2 ) 25 , often accounting for a major portion of the capital cost of solar thermal systems.…”