A team of Chinese researchers has developed a bioinspired material that mimics a leaf's photosynthesis and transpiration processes to harness solar energy and purify water. The technique could benefit the more than one billion people worldwide who live in areas where clean water is scarce.

The researchers, led by Peng Tao and Wen Shang from the Shanghai Jiao Tong University, built a tri-layer bifunctional membrane out of titanium dioxide (TiO2) nanoparticles, gold nanoparticles and a layer of anodized aluminum oxide.

The bioinspired membrane mimics a leaf's processes of photosynthesis and transpiration. Image credit: Morguefile.The membrane cleans water in two ways. In a photosynthesis-like process, the TiO2 layer captures light, which spurs the breakdown of pollutants in a water sample. Testing showed that it degraded about 60% of a model pollutant after two hours in simulated sunlight. The gold layer performs the transpiration role of a leaf, harnessing solar energy and causing water at the sample surface to evaporate.

As the vapor rises, contaminants remain behind. The scientists then condensed the vapor to make purified water.

The process provides an alternative to purification methods currently in use, such as distillation, that commonly rely on fossil-derived energy sources.

The researchers say their demonstration could help open a new strategy for maximizing solar energy conversion and usage.