Actualidad y noticias

New nanomaterials for a cleaner energy generation

07 julio 2017

nanomaterials

There is no doubt that exploring new renewable energy sources is one of the key topics for research centres all over the world. And nanomaterials might have a big say in this field.

New nanomaterials for a cleaner energy generation

There is no doubt that exploring new renewable energy sources is one of the key topics for research centres all over the world. And nanomaterials might have a big say in this field. Semiconductor nanorods based on tungsten oxide have been proved successful in the photoelectrochemical decomposition of water, that is, obtaining hydrogen from water through solar energy. The Nano Energy journal has recently published the results of this study, conducted by the Brno University of Technology (Czech Republic) and the Microsystems and Nanotechnologies for Chemical Analysis (MiNoS) group at the Universitat Rovira i Virgili (Tarragona, Spain).

The properties of tungsten oxide

The research team has focused on the properties of tungsten oxide in the photolectrochemical generation of hydrogen, a storable clean energy source. Semiconductor nanorods have been created from a combination of tungsten, tungsten-on-titanium and an alloy of both compounds. The surface of this nanostructured material absorbs solar energy and acts as an electrode in the electrolysis of water, therefore separating oxygen and hydrogen in a clean way.

Into the technical details

To get these results, porous-anodic-alumina (PAA)-assisted anodization at various conditions has ben applied to arrays of self-organized WO3-based semiconductor nanorods, with two size structures: radius/length ratio of~13/130 and ~70/700 nm (respectively ‘small' and ‘big' nanorods). The post-anodizing treatments combined PAA dissolution with annealing in air and vacuum at 500–550 °C to alter the film composition, crystal structure, and electrical properties. The air-annealed big nanorods comprising monoclinic and triclinic WO3 crystal phases revealed their superior performance in photoelectrochemical (PEC) water splitting, with no sign of photocorrosion.

Still far from practical applications

Although the results of this research line are very promising, the future application still has a long way to run. The capacity of absorbing the solar spectrum is of just 12% and this new nanomaterial is far from offering practical uses at this stage. But new studies will be conducted in order to improve efficiency, as researchers believe that longer and more dense arrays would achieve a higher solar absorption.

C. Rubio