Nanoparticles of titanium dioxide decorated with gold absorb nearly 96% of the solar spectrum and convert it into heat. Hence, the material can expedite the evaporation in desalination plants up to 2.5 times and can detect dangerous compounds and molecules.
An international group of researchers from Far Eastern Federal University (FEFU), ITMO University, and the Far Eastern Branch of the Russian Academy of Sciences has now published a related article in the ACS Applied Materials and Interfaces journal.
The 17th UN Sustainable Development Goals include accessibility to safe water. At the same time, the World Health Organization (WHO) and the Children’s Fund (UNICEF) described the issue in the 2019 report, observing that 2.2 billion people across the world do not have access to safe drinking water.
One of the methods by which clean drinking water can be offered is through desalination of seawater by evaporation and subsequent condensation of steam. To reach higher production, new materials are required to expedite the evaporation. In the last five years, this method has turned out to be a fast-growing research field worldwide.
Such novel materials were developed by researchers from FEB RAS, FEFU and ITMO University jointly with collaborators from Belarus, Bulgaria, Japan and Spain. Scientists claim that it can be utilized as a nano-heater for water evaporation and as an optical detector in sensor systems to detect the smallest traces of several substances in a liquid.
Subsequent properties can be appropriate for lab-on-chips, micro-fluid biomedical systems, and environmental tracking of antibiotics, pollutants, or viruses in water.
Upon laser irradiation, the initially crystalline titanium dioxide became completely amorphous acquiring strong and broadband light absorption properties. Decoration and doping of the material by gold nanoclusters additionally facilitated visible light absorption.
Alexander Kuchmizhak, Senior Researcher, Institute of Automation and Control Processes, Far Eastern Branch of the Russian Academy of Sciences
“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. But the idea came to use it as a kind of nano heater in a desalination tank, which was successfully done in laboratory conditions,” added Kuchmizhak.
The material was achieved with an easy and eco-friendly technology of laser ablation in a liquid.
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 optimized to synthesize unique nanomaterial at gram per hour rate.
Stanislav Gurbatov, Research Participant and Junior Researcher, Polytechnic Institute, School of Engineering, Far Eastern Federal University
Notably, the first nanoparticles of titanium dioxide do not absorb visible laser radiation. But they catalyze the development of nanosized gold clusters on their surface, which stimulates additional melting of titanium dioxide.
Various hybrid nanoparticles fuse by developing special nanomorphology, wherein gold nanoclusters are situated both within and on the surface of titanium dioxide.
Gold-decorated amorphous titanium dioxide nanopowder looks entirely black to the human eye as it effectively absorbs within the complete visible light spectrum similar to a black hole in space and transforms it into heat. In total contrast, the commercial titanium dioxide powder utilized as a starting material appears to be white.
The advent of new materials, such as those that support new manageable physical principles for an extensive range of applications, falls within priority areas of FEFU, on which researchers are working in close collaboration with the Russian Academy of Sciences, domestic and foreign collaborators.
The study was financially supported by the Russian Science Foundation (grant no. 19-79-00214).
Gurbatov, S. O., et al. (2021) Black Au-Decorated TiO2 Produced via Laser Ablation in Liquid. ASC Applied Materials & Interfaces. doi.org/10.1021/acsami.0c20463.