Gold-decorated titanium dioxide nanoparticles can speed up water desalination

(Reference image by Jong Myung Lim, Pxhere).

An international research team discovered that it is possible to use titanium dioxide nanoparticles with gold to accelerate the evaporation in desalination plants up to 2.5 times and track hazardous molecules and compounds.

In a paper published in the journal ACS Applied Materials and Interfaces, the researchers explain that the nanoparticles are able to absorb about 96% of the solar spectrum and turn it into heat. 

According to one of the study authors, Alexander Kuchmizhak from the Far Eastern Branch of the Russian Academy of Sciences, when the material he and his group developed was put through laser ablation in a liquid, the initially crystalline titanium dioxide became completely amorphous and acquired strong and broadband light absorption properties. Decoration and doping of the material with gold nanoclusters additionally facilitated visible light absorption. 

Decoration and doping of the titanium dioxide with gold nanoclusters facilitated visible light absorption

In detail, what the team did was adding titanium dioxide nanopowders to a liquid containing gold ions and irradiated the mixture with laser pulses of the visible spectrum. The method does not require expensive equipment, hazardous chemicals and can be easily optimized to synthesize unique nanomaterials at a gram-per-hour rate.

“Initially, we intended to use the feature in the context of solar energy but quickly realized that due to the new amorphous structure nanoparticles in the active layer of solar cells will convert the absorbed solar energy into heat rather than electricity,” Kuchmizhak said. “But the idea came to use it as a kind of nano-heater in a desalination tank, which was successfully done in laboratory conditions.”

The scientist noted that the initial nanoparticles of titanium dioxide do not absorb visible laser radiation. However, they catalyze the formation of nanosized gold clusters on their surface stimulating further melting of titanium dioxide. Several hybrid nanoparticles fuse and form a unique nanomorphology, in which gold nanoclusters are located both inside and on the surface of titanium dioxide.

Au-decorated amorphous titanium dioxide nanopowder appears completely black to the human eye since it efficiently absorbs light within the entire visible light spectrum and converts it into heat. In sharp contrast, the commercial titanium dioxide powder used as a starting material is white.

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