EES Blog

Credit: Foreign Policy magazine

We are delighted to announce that Energy and Environmental Science authors Florent Boudoire, Rita Toth, Jakob Heier, Artur Braun and Edwin C. Constable have been listed among Foreign Policy magazine’s “100 Leading Global Thinkers of 2014” for their work on advancing solar technology using rust and moth eyes.

The researchers are based at the Swiss Federal Laboratories for Materials Science and Technology and the University of Basel, Switzerland and were honoured in the innovators section. The Foreign Policy editors noted on their work that ‘The advance opens up a new method for hydrogen-fuel production and could let the next generation of solar technologies take wing.’

For further information take a look at the Global Thinkers website and make sure to read the original EES article!

Photonic light trapping in self-organized all-oxide microspheroids impacts photoelectrochemical water splitting
Florent Boudoire, Rita Toth, Jakob Heier, Artur Braun and Edwin C. Constable
Energy Environ. Sci., 2014,7, 2680-2688

 Abigail Hallowes writes about an EES article in Chemistry World

Researchers from the US have optimised a photoelectrochemical cell (PEC) so that it can continuously split water into clean burning hydrogen and oxygen for over 2200 hours – the equivalent to one year of outdoor operation.

In order for PECs to be a competitive energy provider, they should efficiently covert solar into chemical energy, whilst remaining stable for years of continuous operation. The condition of the electrodes in PECs is a major concern as they immediately start to corrode once immersed in the electrolyte. Previous PEC researchers have only been able to produce systems that are either stable for 4–100 hours but inefficient, or efficient but only stable for a few minutes; they have not been able to incorporate both required properties.

Scanning-electron micrograph image of a microwire array with its protective coating

 
Electrode instability is brought on when the energy required to excite an electron is within the same energy range that causes electrode corrosion; photocorrosion then becomes competitive with water splitting. In these cases, it is most likely that photocorrosion is thermodynamically more favourable which therefore leads to unstable electrodes. Now, a team led by Nathan Lewis at the California Institute of Technology have drastically increased PEC stability whilst achieving a 100% Faradaic efficiency for oxygen evolution.
 
Their approach increased the electrochemically active sites versus the surface area of the electrode through the use of silicon microwire arrays; this led to a decrease in the effective current density at the electrode–electrolyte interface, increasing the energy required for photocorrosion, which decreased the rate of photocorrosion. They also coated the arrays in a protective but conductive layer, to act as a corrosion-resistant barrier while maintaining efficient charge transfer to the reaction sites, as well as with an oxygen evolution catalyst to promote water oxidation.
 
Brian Seger, a photoelectrochemist at the Technical University of Denmark, explains that water splitting provides some very corrosive conditions so stability has been a large hurdle in this field: ‘The fact that the Lewis group could test their device for three months with no noticeable corrosion indicates that this hurdle is surmountable.’
 
Materials scientist, Dongyuan Zhao, of Fudan University, China, describes the work was a breakthrough and says it ‘shows great potential for industrial application.’

Interested to find out more? Read the full article by Abigail Hallowes in Chemistry World.

Read the original article in Energy and Environmental Science:

Stabilization of Si microwire arrays for solar-driven H2O oxidation to O2(g) in 1.0 M KOH(aq) using conformal coatings of amorphous TiO2
Matthew R. Shaner,ab   Shu Hu,ab   Ke Sunab and   Nathan S. Lewis
Energy Environ. Sci., 2015, Advance Article
DOI: 10.1039/C4EE03012E

Scientists in Germany have developed a highly targeted metabolic engineering technique to control the flow of electrons produced by the initial stages of photosynthesis in microalgae, and used it to increase hydrogen production by a factor of five.

Hydrogen is increasingly being touted as an environmentally friendly alternative to conventional fossil fuels, but, ‘at present, hydrogen is mainly produced from natural gas, which makes it a “wolf in sheep’s clothing”,’ comments Oliver Inderwildi, a senior policy fellow at the Smith School of Enterprise and the Environment, University of Oxford, UK. Natural microalgae produce hydrogen by harnessing energy from sunlight, but their low production rate limits their practical application. Organisms typically use most of the electrons they generate to make the carbohydrates they need to live.

Previous studies in this area had focussed on curbing carbohydrate production. Now, Wolfgang Lubitz, of the Max Planck Institute for Chemical Energy Conversion, and co-workers have modified a ferredoxin protein responsible for distributing photo-generated electrons in the green algae Chlamydomonas reinhardtii with the aim of boosting its hydrogen output, whilst allowing the organism to be self-sustaining.

Interested to find out more? Read the full article by Jonathan Midgley in Chemistry World.

Read the original article in Energy & Environmental Science:

Enhancing hydrogen production of microalgae by redirecting electrons from photosystem I to hydrogenase
Sigrun Rumpel, Judith F. Siebel, Christophe Farès, Jifu Duan, Edward Reijerse, Thomas Happe, Wolfgang Lubitz and Martin Winkler
Energy Environ. Sci., 2014, Advance Article
DOI: 10.1039/C4EE01444H