New photocatalyst made from an aerogel for more efficient hydrogen production

 

Researchers at ETH Zurich have developed a new photocatalyst made from an aerogel that could enable more efficient hydrogen production. One use for aerogels based on nanoparticles is as photocatalysts. These are employed whenever a chemical reaction needs to be enabled or accelerated with the aid of sunlight – one example being the production of hydrogen.

The material of choice for photocatalysts is titanium dioxide (TiO2), a semiconductor. But TiO2 has a major disadvantage: it can absorb only the UV portion of sunlight – just about 5 percent of the spectrum. If photocatalysis is to be efficient and industrially useful, the catalyst must be able to utilise a broader range of wavelengths. Junggou Kwon has been looking for a new way to optimise an aerogel made of TiO2 nanoparticles. And she had a brilliant idea: if the TiO2 nanoparticle aerogel is “doped” (to use the technical term) with nitrogen, such that individual oxygen atoms in the material are replaced by nitrogen atoms, the aerogel can then absorb further visible portions of the spectrum. The doping process leaves the aerogel’s porous structure intact. Kwon developed a special reactor into which she directly placed the aerogel monolith. She then introduced a vapour of water and methanol to the aerogel in the reactor before irradiating it with two LED lights. The gaseous mixture diffuses through the aerogel’s pores, where it is converted into the desired hydrogen on the surface of the TiO2 and palladium nanoparticles. Adding the noble metal palladium significantly increased the conversion efficiency: using aerogels with palladium produced up to 70 times more hydrogen than using those without.

Photo ETH Zurich



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