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.