A nanoparticle photocatalyst that works under natural light and could be used to remove pollutants from water has been developed by scientists in China and Japan. 

Photocatalysts use light to speed up a reaction but most need ultra-violet light to work. Now, Renhong Li at the Zhejiang Sci-Tech University, China and colleagues have used bismuth to make a catalyst that works under visible light. 

Li's catalyst uses platinum nanoparticles loaded with the semiconductor bismuth oxide (Bi₂O₃). The Bi₂O₃ allows transfer of electrons to take place on excitation by visible light. This generates holes on the surface that decompose organic molecules such as acetaldehyde and formaldehyde. 

The reaction rates achieved by this new catalyst are comparable to ones that use UV light, says Li. 'Since most of the present photocatalysts can only be photoexcited by UV light, our Pt/Bi₂O₃  catalyst  is very useful for energy saving purposes,' he adds.

Leonardo Palmisano, a photocatalysis researcher at the University of Palermo, Italy says 'this shows some convincing results on the photo-oxidation of organic pollutants under visible light illumination, demonstrating an important plasmonic effect for Pt/Bi₂O₃ photocatalysts.' He adds that he sees promising applications for the new catalyst. 

Li says that this research could provide advances in the use of platinum and other noble metals photocatalysts, such as the use of photocatalysts in water splitting under visible light which is an area the team hope to explore further.

Rebecca Brodie

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