Dual-Functional Graphene Oxide-Based Photothermal Materials with Aligned Channels and Oleophobicity for Efficient Solar Steam Generation

Abstract

Desalination by solar steam generation (SSG) has emerged as one of the most efficient approaches to address the issue of global water shortage. In this work, novel graphene oxide (GO)-based solar steam generators (GO-SSGs) with aligned channels were prepared by directional freezing and simple carbonization of a hydrogel composed of GO and poly(vinyl alcohol) (PVA). Benefitting from their excellent light absorption (light absorption efficiency exceeds 94%), better thermal insulation (thermal conductivity, 0.259 W/(m K)), and suitable porous structure, which facilitates rapid water transportation, the GO-SSGs show superior SSG performance with a high solar energy conversion efficiency of up to 92% achieved under an irradiation of 1.0 kW/m 2 . Interestingly, uniquely aligned channels endow them with good salt-rejection performance; the solar energy conversion efficiency of GO-SSGs in 20 wt % NaCl, KCl, and MgCl 2 brine can reach more than 85%. To improve their antifouling performance, a chemically hydrophilic and oleophobic modification was conducted, making it possible to run SSG even in oily wastewater; for instance, a solar energy conversion efficiency of 84% was obtained in an aqueous solution containing 10 wt % n-hexadecane. Compared with the existing photothermal materials, these materials show advantages of simple manufacture, high SSG efficiency, superior salt tolerance, and antifouling performance, which make them promising candidates as a kind of new high-performance photothermal materials for desalination even in oily wastewater, thus further expanding the scope of their practical SSG application.

Designing Photothermal Superhydrophobic PET Fabrics via In Situ Polymerization and 1,4-Conjugation Addition Reaction

“…Among them, photothermal conversion technology is the most direct application of solar energy. Photothermal conversion materials which can directly convert absorbed light energy into thermal energy have been widely used in photothermal energy storage, , photothermal deicing, , seawater desalination, , and light-driven. , These materials usually include metallic materials, , carbonaceous materials, − and conducting polymers . However, photothermal conversion materials face serious rainwater corrosion and environmental pollutant pollution problems during long-term outdoor operation, which significantly affects their performance stability and service life.…”

Recent advances in structural regulation and optimization of high-performance solar-driven interfacial evaporation systems

“…94 Graphene oxide (GO) and reduced graphene oxide (rGO) have been applied to SIE. 18,[95][96][97][98][99] A 3D interconnected porous maize straw/GO aerogel with an evaporation efficiency of 3.22 kg m À2 h À1 under one sun was synthesized by low-temperature hydrothermal reduction and atmospheric drying. 100 The addition of urea for nitrogen doping, on the one hand, regulated the p-p stacking among GO sheets, while on the other hand, increased the reduction degree and hydrophilicity of GO.…”

“…[11][12][13] Besides, the SIE of wastewater such as dye wastewater, heavy metal wastewater, oily wastewater, and radioactive wastewater has also been studied. [14][15][16][17][18][19] SIE performance is primarily determined by two indicators: evaporation rate and evaporation efficiency. The evaporation rate is the amount of water vapor generated by the unit area of the evaporation interface in unit time, which most intuitively reects the ability of an evaporation system to produce water vapor.…”

“…11–13 Besides, the SIE of wastewater such as dye wastewater, heavy metal wastewater, oily wastewater, and radioactive wastewater has also been studied. 14–19…”

Coffee Grounds-Doped Alginate Porous Materials for Efficient Solar Steam Generation

“…Tremendous efforts have been made to discover ideal SSG photothermal materials for fresh water production. Up to now, plenty of materials with high conversion efficiency have been developed, including carbon-based materials, − metal nanoparticles, , porous polymer materials, − semiconductor materials, aerogels and hydrogels, − natural materials, , and 3D printing materials . Though various photothermal materials have been reported, from a practical application point of view, exploring low-cost photothermal materials with high performance and simple fabrication is of much more importance.…”