A Light-Permeable Solar Evaporator with Three-Dimensional Photocatalytic Sites to Boost Volatile-Organic-Compound Rejection for Water Purification

Abstract

Solar-driven interfacial evaporation (SIE) is emerging as an energy-efficient technology to alleviate the global water shortages. However, there is a fatal disadvantage in using SIE, that is, the volatile organic compounds (VOCs) widely present in feedwater would concurrently evaporate and transport in distilled water, which threatens the water safety. Photocatalysis is a sustainable technology for pollution control, and after years of development, it has become a mature method. Considering the restriction by the insufficient reaction of the permeating VOCs on the two-dimensional (2D) light-available interface of conventional materials, a 3D photocatalytic approach can be established to boost VOC rejection for photothermal evaporation. In the present work, a light-permeable solar evaporator with 3D photocatalytic sites is constructed by a porous sponge decorated with BiOBrI nanosheets with oxygen-rich vacancies. The 3D microchannels in the evaporator provide a light-permeable path with the deepest irradiation depth of about 580 μm, and the reactive interface is increased by tens of times compared with the traditional 2D membrane, resulting in suppression of VOC remnants in distilled water by around four orders of magnitude. When evaporating river water containing 5 mg L–1 extra added phenol, no phenol residues (below 0.001 mg/L) were detected in the produced freshwater. This development is believed to provide a powerful strategy to resolve the VOC bottleneck of SIE.

High-Efficiency Photo-Thermo-Electric System with Waste Heat Utilization and Energy Storage

“…At present, there are two main ways to convert solar energy into electrical energy. − One is a photovoltaic technology in which electron–hole pairs can be generated efficiently. − However, the environment was seriously polluted in the fabrication process of photovoltaic devices. The other one is a photo-thermo-electric technology in which solar energy is first converted into heat − and then into electrical energy. − Compared with photovoltaic devices, the fabrication process of photo-thermo-electric devices is cleaner. − …”

Aerogels in passive solar thermal desalination: a review

“…Owing to the presence of sunlight in STD systems, simultaneous photocatalytic degradation of VOCs was proposed along with the water evaporation process. 111 To do so, a 3D porous sponge was decorated with BiOBrI nanosheets with oxygen-rich vacancies. The obtained results revealed detection of less than 0.001 ppm phenol residues in the produced water from the bulk river water containing 5 ppm phenol.…”

A Floating Integrated Solar Micro‐Evaporator for Self‐Cleaning Desalination and Organic Degradation

“…[ 11 ] However, substantial challenges remain in developing a versatile solar system toward the functional synergy between photodegradation and solar desalination: 1) abundant interfacial reactive sites for efficient photodegradation of organics, in which photocatalysis occurs at the light‐available interface, 2) high solar absorption capability for solar‐thermal evaporation, and 3) sufficient transport pathways for continuous water supply. The recently reported photocatalytic solar evaporators [ 11c,12 ] for the revival of organic‐containing saline wastewater severely suffer from the serious salt scale, fouling, and relatively slow degradation rate during evaporation. In this regard, a floatable micro‐evaporator system with smart self‐rotation can achieve self‐cleaning desalination during solar steam generation.…”