Bio4Energy results. An international group of scientists have found an "ultra-efficient" way to make hydrogen from renewable raw materials. The method is directly applicable and, if adopted by industry, could be used to produce the gas on a commercial scale. In a second step the scientists hope to run the conversion process on renewable energy from the sun.
The discovery, first published online in the ASC Nano scientific journal, was made by a team of researchers from Hungary, Finland, Sweden, Taiwan and the U.S.A., led by Krisztián Kordás of Bio4Energy.
In the early 2000s, world leaders such as U.S. President George W. Bush and European Union supremos were hailing hydrogen as the next source of "clean" energy. Large sums of money were poured into research and development of fuel cell technology drawing on this naturally-occurring gas said to leave little more than water vapour in the trail behind the exhaust pipe when used to propel an automotive engine.
However, while today hydrogen is used across a range of applications, frequently it has been converted into a process gas by using nuclear power or fossil fuels. Moreover, unresolved issues of transport and storage are hurdles to rolling out hydrogen fuel cells for use in automotive transport.
Based on their expertise in nanotechnology and photocatalysis—the acceleration of a photoreaction in the presence of a catalyst—the international research team shepherded by Kordás decided to tackle the issue partly from a different angle. They bid to render the production of hydrogen itself more efficient, so that a greater output per unit of raw material, or "feedstock", could be achieved. The process also had to be clean.
Catalyst + feedstock + UV radiation = hydrogen
They joined a long line of research drawing on titanium dioxide (TiO2) as a semiconducting material. Based on TiO2 nanofibers they developed a series of new catalysts, each of which were added to a mixture of ethanol and water and exposed to ultraviolet radiation. A comparison made with similar catalytic processes relying on TiO2 as a semiconductor revealed that this doubled or even tripled the efficiency of the conversion, according to an annex to the scientists' article listed by ASC Nano as "Supporting info".
"[W]e… demonstrate for the first time an ultra-efficient H2 generation from water-ethanol mixtures under UVA and UVB irradiation", their article said.
Kordás, who is an assistant professor at Umeå University in Sweden, and a senior lecturer at the Finnish University of Oulu, said that methods similarly drawn from semiconductor-based photocatalytic research had been invented for wastewater treatment, air purification and antimicrobial coatings. Efforts had also been made to design efficient catalysts for hydrogen production but, to his team’s knowledge, none matched the efficiency of those which it had developed.
"We added only a small amount of the catalyst powders obtained to a water-ethanol mixture, and found that such photocatalyst materials clearly outperform their conventional TiO2 nanoparticle-based counterparts in developing hydrogen gas from ethanol under UV irradiation", Kordás explained in a note.
A next step would be to adapt the process to the full spectrum of electromagnetic radiation contained in sunlight.
"In this more efficient way of producing hydrogen, we [want to be] using solar energy instead of energy-demanding electrolytic and steam reforming processes… which are the standard. Solar energy is a free and entirely pure energy source", the note said;
"Using photocatalytic converters with good efficiencies to generate hydrogen from a raw feedstock, the difficulties related to storage may be reduced or even eliminated.
"In an ideal case… the feedstock could be stored and transported, whereas the hydrogen [should be] produced at the spot of use", according to Kordás.
*The following authors contributed to the article, Nitrogen-doped Anatase Nanofibers Decorated with Nobel Metal Nanoparticles for Photocatalytic Production of Hydrogen (cited 25 August 2011).
- Ming-Chung Wu, University of Oulu, Finland/National Taiwan University;
- Jussi Hiltunen, University of Oulu, Finland;
- András Sápi, University of Szeged, Hungary;
- Anna Avila, University of Oulu, Finland;
- William Larsson, Umeå University, Sweden - Bio4Energy;
- Hsueh-Chung Liao, National Taiwan University, Taiwan;
- Mika Huuhtanen, University of Oulu, Finland;
- Géza Tóth,University of Oulu, Finland;
- Andrey Shchukarev, Umeå University, Sweden;
- Noémi Laufer, University of Szeged, Hungary;
- Ákos Kukovecz, University of Szeged, Hungary;
- Zoltán Kónya, University of Szeged, Hungary;
- Jyri-Pekka Mikkola, Umeå University, Sweden/Åbo Akademi, Finland - Bio4Energy;
- Riitta Keiski, University of Oulu, Finland;
- Wei-Fang Su, National Taiwan University, Taiwan;
- Yang-Fang Chen, National Taiwan University, Taiwan;
- Heli Janutnen, University of Oulu, Finland;
- Pulickel M. Ajayan, Rice University, Texas, U.S.A.;
- Robert Vajtai, Rice University, Texas, U.S.A; and