Constructing Black Titania with Unique Nanocage Structure for Solar Desalination

Abstract

Solar desalination driven by solar radiation as heat source is freely available, however, hindered by low efficiency. Herein, we first design and synthesize black titania with a unique nanocage structure simultaneously with light trapping effect to enhance light harvesting, well-crystallized interconnected nanograins to accelerate the heat transfer from titania to water and with opening mesopores (4-10 nm) to facilitate the permeation of water vapor. Furthermore, the coated self-floating black titania nanocages film localizes the temperature increase at the water-air interface rather than uniformly heating the bulk of the water, which ultimately results in a solar-thermal conversion efficiency as high as 70.9% under a simulated solar light with an intensity of 1 kW m (1 sun). This finding should inspire new black materials with rationally designed structure for superior solar desalination performance.

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Oxygen‐Defected Molybdenum Oxides Hierarchical Nanostructure Constructed by Atomic‐Level Thickness Nanosheets as an Efficient Absorber for Solar Steam Generation

“…However, this process usually suffers form high concentration sunlight because of the large energy losses, which hinders the large‐scale productions. To enhance the energy conversion efficiency, a method constructing floating porous photo‐thermal materials at the air‐water interface has attracted extensive attentions . Similar to natural plant transpiration and human sweating system, the heat generated by absorbers can be effectively localized at the interface and facilitate the vapor production.…”

“…Up to now, the commonly used materials in solar evaporation system include metallic plasmonic nanostructures, carbon‐based materials, and polymers . However, there are few investigates about applying transition metal oxides (TMOs) as solar receivers, which possess unique optical properties and widely used in photocatalysts, solar cells, photothermal conversions, photoelectrochemical (PEC) conversions, etc. Thus, it's significant to explore TMOs as absorbers to expand the scope of materials used in solar evaporation system.…”

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“…Considering that the lamellar structures possess the good abilities of effectively increasing light trapping, Huang's group prepared a black titanium nanocage via a molten salt‐assisted method. The as‐fabricated black titanium nanocage for the ISSG device not only can utilize more heat energy for water desalination via optical‐thermal effect, but also can provide the paths for water steam to pass through mesopores, which achieves an ultra‐high evaporation efficiency as much as 70.9% under the radiation of simulated solar light with an intensity of 1 kW · m −2 (Figure d) . This work may also inspire researchers to develop more new black materials with rationally designed structure to realize the desired performance for solar desalination of seawater.…”

“…d) Black titanium nanocage as ISSG device. Reproduced with permission . Copyright 2017, American Chemical Society.…”