An international research team discovered that titanium dioxide nanoparticles can be used with gold to speed up the evaporation of seawater desalination plants by 2.5 times and track dangerous molecules and compounds.

In a paper published in the journal ACS Applied Materials and Interfaces, the researchers stated that nanoparticles can absorb about 96% of the solar spectrum and convert it into heat. 

According to one of the study authors, Alexander Kuchmizhak of the Far East Branch of the Russian Academy of Sciences, when the material is laser ablated in a liquid, the initial crystalline titanium dioxide becomes completely amorphous and obtains Strong broadband light absorption characteristics. Decorating and doping with gold nanoclusters also promotes visible light absorption. 

Decorating with gold nanoclusters and doping with titanium dioxide to promote visible light absorption

In detail, what the team did was to add titanium dioxide nanopowder to a liquid containing gold ions and irradiate the mixture with laser pulses in the visible spectrum. This method does not require expensive equipment and hazardous chemicals, and can be easily optimized to synthesize unique nanomaterials at a speed of grams per hour.

Kuchmizhak said: "Initially, we intended to use this feature in the context of solar energy, but soon realized that due to the new amorphous structured nanoparticles in the active layer of the solar cell, the absorbed solar energy was converted into heat instead of electrical energy." But our idea is to use it as a kind of nano heater in a desalination tank and successfully complete it under laboratory conditions."

The scientist pointed out that the original titanium dioxide nanoparticles did not absorb visible laser radiation. However, they catalyze the formation of nano-sized gold clusters on their surface, thereby stimulating further melting of titanium dioxide. Several mixed nanoparticles fuse and form a unique nanomorphology, in which gold nanoclusters are located inside and on the surface of titanium dioxide.

The gold-decorated amorphous titanium dioxide nanopowder looks completely black to the human eye because it can effectively absorb light in the entire visible spectrum and convert it into heat. In sharp contrast, the commercial titanium dioxide powder used as the starting material is white.