ABSTRACT
The design and development of scalable, efficient photothermal evaporator systems that reduce microplastic pollution are highly desirable. Herein, a sustainable bacterial nanocellulose (BNC)-based self-floating bilayer photothermal foam (PTFb) is designed that eases the effective confinement of solar light for efficient freshwater production via interfacial heating. The sandwich nanoarchitectured porous bilayer solar evaporator consists of a top solar-harvesting blackbody layer composed of broad-spectrum active black titania (BT) nanoparticles embedded in the BNC matrix and a thick bottom layer of pristine BNC for agile thermal management, the efficient wicking of bulk water, and staying afloat. A decisive advantage of the BNC network is that it enables the fabrication of a lightweight photothermal foam with reduced thermal conductivity and high wet strength. Additionally, the hydrophilic three-dimensional (3D) interconnected porous network of BNC contributes to the fast evaporation of water under ambient solar conditions with reduced vaporization enthalpy by virtue of intermediated water generated via a BNC-water interaction. The fabricated PTFb is found to yield a water evaporation efficiency of 84.3% (under 1054 W m-2) with 4 wt % BT loading. Furthermore, scalable PTFb realized a water production rate of 1.26 L m-2 h-1 under real-time conditions. The developed eco-friendly BNC-supported BT foams could be used in applications such as solar desalination, contaminated water purification, extraction of water from moisture, etc., and thus could address one of the major present-day global concerns of drinking water scarcity.
Subject(s)
Acetobacteraceae/chemistry , Biocompatible Materials/chemistry , Cellulose/chemistry , Nanoparticles/chemistry , Sunlight , Titanium/chemistry , Hydrophobic and Hydrophilic Interactions , Materials Testing , Particle Size , Water PurificationABSTRACT
Ideal multifunctional ultraviolet radiation (UVR) absorbents with excellent photostability, high molar absorptivity, broadband UVR screening, and desired skin sensorial properties remain a significant challenge for the sunscreen industry. The potential of the nanocomplex (NCx) formed by microwave synthesis of ZnO quantum dots (QDs) in the presence of Avobenzone (Av) for achieving these goals is reported. The NCx exhibits unique synergy between ZnO QD and Av components, which enhances the photostability and molar absorptivity, extends UVA filtering range, and provides a visible emission that matches the typical human in vivo skin emission color. Density functional theory (DFT) and time-dependent DFT calculations of ZnO-Av hybrid structures and comparison of their spectroscopic features with experiments suggest that ZnO QDs catalyze the formation of highly photostable surface enolate species via aldol condensation reaction. The combination of experiments and computations used in this study can advance the science and technology of photoprotection.
