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Titanium dioxide nanoparticles ‘decorated’ with gold absorb about 96% of the solar spectrum and turn it into heat, said the researchers from the Far Eastern Federal University, Itmo University and the Far Eastern Branch of the Russian Academy of Sciences, who worked with colleagues from Spain, Japan, Bulgaria, and Belarus to develop and test the material. It could make evaporation in desalination plants up to 2.5-times quicker, while also tracking hazardous molecules and compounds.
According to the World Health Organisation and Unicef, 2.2bn people do not have access to safely managed drinking water. One way to provide clean drinking water is to desalinate seawater by evaporation and concentrate the steam. New materials could boost production by accelerating the evaporation.
The team said its new material can be used as a ‘nano-heater’ for water evaporation, and as an optical detector in sensor systems tracking small traces of various substances in liquid.
The ‘Au-decorated amorphous titanium dioxide nanopowder’ appears completely black to the human eye, thanks to its efficient absorption of the entire visible light spectrum, which it converts into heat.
“Upon laser irradiation, the initially crystalline titanium dioxide became completely amorphous, acquiring strong and broadband light absorption properties,” said author Alexander Kuchmizhak from the Russian Academy of Sciences. “Decoration and doping of the material by gold nanoclusters additionally facilitated visible light absorption.”
The researchers initially planned to exploit the material’s properties in a solar energy application, but they realised absorbed solar energy is converted to heat rather than electricity. Instead, they decided to use it as a nano-heater in a desalination tank, which they did in laboratory conditions.
Production of the material was done by laser ablation in a liquid, the team said.
“We added 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 optimised to synthesise unique nanomaterial at gram-per-hour rates,” said researcher Stanislav Gurbatov from the Far Eastern Federal University.
Other properties of the material could make it useful for micro-fluid biomedical systems, ‘labs on chips’, and environmental monitoring of pollutants, antibiotics or viruses in water.
The research was published in ACS Applied Materials and Interfaces.
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