Hailed as a possible breakthrough that could help avert shortages of potable water in many parts of the world in future, the system consists of three layers of nanoparticles mimicking natural processes of photosynthesis and transpiration.

A layer of titanium oxide (TiO2) captures light and turns it into energy that induces the breakdown of toxic pollutants. Up to 60 per cent of contaminants present in the sample could be removed this way in two hours of sun exposure. A layer of gold nanoparticles subsequently harnesses solar energy to drive evaporation of water from the surface of the partially purified sample in a process simulating natural transpiration. The water vapour is free from contaminants, which remain in the original sample. The final step is condensation of the water vapour. The resulting water is perfectly purified.

While scientists have been pursuing artificial photosynthesis for years as a way to produce hydrogen from water and sunlight, the water purification system is an entirely new application of the artificial leaf technology.

Described in the latest issue of the journal ACS Applied Materials & Interfaces, the technology could provide an environmentally friendly alternative to currently prevalent methods of water purification relying mostly on fossil fuel-based energy.

About one billion people around the world currently struggle with a lack of drinkable water and the number is expected to rise due to the projected population growth. Waste water purification is generally considered as one of the most viable approaches to solve the problem.

The artificial leaf water purification system was developed by a team led by Peng Tao and Wen Shang from the Shanghai Jiao Tong University in China.

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