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Redirecting electrons boosts algal hydrogen generation

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 The hydrogen yield from green algae like Chlamydomonas reinhardtii is normally restricted by physiological constraints © AMI Images/Science Photo Libraryfive.

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

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Wind-powered lighting is almost a breeze

Scientists in South Korea have created a material that emits bright white light when a stream of nitrogen is blown over it. The discovery paves the way for eco-friendly displays and lighting systems powered by natural winds.A stream of air causes the rods to bend, emitting light from the phosphors

Mechanoluminescence, where materials emit light under mechanical stress, is not a new phenomenon; in 1605 Francis Bacon reported seeing flashes of light when he snapped sugar crystals. But, as this required the crystals to be fractured, mechanoluminescence was not thought to have any practical applications until elasto-mechanoluminescent materials were discovered in 1999. These materials emit light under elastic deformation without being destroyed, and can be used for lighting, medical imaging or even as artificial skin.

However, all of the elasto-mechanoluminescent materials discovered so far have several associated problems. One problem is the light they produce is very faint, and is usually only as bright as luminescent paint. Another problem is that the light is coloured, often green or yellow, depending on the compounds used. This is a stumbling block for applications where white light is preferable.

Both of these problems have been addressed by Soon Moon Jeong’s team from the Daegu Gyeongbuk Institute of Science and Technology. By incorporating a mixture of coloured phosphors made from copper-doped zinc sulfide into a flexible plastic polydimethylsiloxane composite, the researchers created an elasto-mechanoluminescent material that emits white light. The colour of the light can also be tuned by changing the proportion each phosphor.

Interested to find out more? Read the full article by Stephen McCarthy in Chemistry World.

Read the original article in Energy & Environmental Science:

Bright, wind-driven white mechanoluminescence from zinc sulphide microparticles embedded in a polydimethylsiloxane elastomer
Soon Moon Jeong, Seongkyu Song, Kyung-Il Joo, Joonwoo Kim, Sung-Ho Hwang, Jaewook Jeong and Hyunmin Kim
Energy Environ. Sci., 2014, Advance Article
DOI: 10.1039/C4EE01776E

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Spray-deposition steers perovskite solar cells towards commercialisation

A low-cost, high-efficiency technique for fabricating perovskite solar cells – ultra-sonic spray-coating – has been Spray-coated perovskite solar cells © Lucy Pickforddeveloped by a team of researchers in the UK. It represents a significant step towards commercialising perovskite solar cells.

David Lidzey, head of the research group at the University of Sheffield behind the study, explains that there has been ‘interest in developing solar cell materials that are easy to process, efficient and have less embodied energy than current technologies.’

Thin-film solar cells using perovskite semi-conductors have become a promising form of photovoltaic device achieving power conversion efficiencies of up to 15–19%, surpassing the efficiencies of amorphous silicon and organic semi-conductor photovoltaics.

Perovskite films can be fabricated by depositing precursor materials from solution. However, there have been few reports detailing the application of scalable solution-processing techniques to create these films.

In this study, an ultra-sonic spray-coating of methylamine iodide and lead chloride created a thin film of a perovskite precursor under ambient conditions. The film was then thermally annealed into a CH3NH3PbI3–ᵪClᵪ perovskite structure prior to inclusion within a solar cell with a planar heterojunction architecture.

Interested to find out more? Read the full article by Vicki Marshall in Chemistry World.

Read the original article in Energy and Environmental Science:

Efficient planar heterojunction mixed-halide perovskite solar cells deposited via spray-deposition
Alexander T. Barrows, Andrew J. Pearson, Chan Kyu Kwak, Alan D. F. Dunbar, Alastair R. Buckley and David G. Lidzey
Energy Environ. Sci., 2014, Advance Article
DOI: 10.1039/C4EE01546K 

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Organic solar cells reach manufacturing milestone

In an impressive feat of engineering, scientists in Denmark have devised a rapid, scalable and industrially viable way to manufacture large sheets of flexible organic tandem solar cells. Their successful application of roll-to-roll processing is a significant achievement for this emerging renewable technology.Organic solar cells reach manufacturing milestone

An organic photovoltaic (OPV) solar cell is a polymer-based thin film solar cell. OPV solar cells have been the focus of much research as they are lightweight, flexible, inexpensive, highly tuneable and potentially disposable. They are also unparalleled in the number of times that they can pay back the energy used in their manufacture.

In the quest to improve the efficiency of OPVs, which, in addition to operational lifetime, is currently their key limitation, various new materials, processing methods and device architectures have been investigated. Among these is the tandem cell, where multiple junctions are stacked upon one another. This can increase the efficiency of the cell by not only increasing the number of junctions, but, along with careful selection of complimentary materials, can make it possible to harvest photons from a broader region of the spectrum. However, this more complicated architecture renders their manufacture significantly more challenging.

Interested to find out more? Read the full article by William Bergius in Chemistry World.

Read the original article in Energy and Environmental Science:

Scalable, ambient atmosphere roll-to-roll manufacture of encapsulated large area, flexible organic tandem solar cell modules
Energy Environ. Sci., 2014, Advance Article
DOI: 10.1039/C4EE01223B
Thomas R. Andersen, Henrik F. Dam, Markus Hösel, Martin Helgesen, Jon E. Carlé, Thue T. Larsen-Olsen, Suren A. Gevorgyan, Jens W. Andreasen, Jens Adams, Ning Li et al.

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The future is lead-free for perovskite solar cells

A lead-free and non-toxic alternative to current perovskite solar-cell technology has been reported by researchers in the UK: tin halide perovskite solar cells. They are also cheaper to manufacture than the silicon solar cells currently dominating the market.The future is lead-free for perovskite solar cells

Nakita Noel, part of Henry Snaith’s research team at the University of Oxford, describes how perovskite materials have caused a bit of a whirlwind since they came out in 2009: ‘Everybody that’s working in the solar community is looking to beat silicon.’ Despite the high efficiency of conventional crystalline silicon solar cells (around 20%), high production and installation costs decrease their economic feasibility and widespread use.

The challenge to find a cheaper alternative led to the development of perovskite-based solar cells, as organic–inorganic metal trihalide perovskites have both abundant and cheap starting materials. However, the presence of lead in some semiconductors could create toxicology issues in the future. As Noel puts it ‘every conference you present at somebody is bound to put up their hand and ask “What about the lead – isn’t this toxic?”

Interested to find out more? Read the full article by Vicki Marshall in Chemistry World.

Read the original article in Energy & Environmental Science.

Lead-Free Organic-Inorganic Tin Halide Perovskites for Photovoltaic Applications
Nakita K. Noel, Samuel D. Stranks, Antonio Abate, Christian Wehrenfennig, Simone Guarnera, Amir Haghighirad, Aditya Sadhanala, Giles E Eperon, Sandeep K. Pathak, Michael B Johnston, annamaria petrozza, Laura Herz and Henry Snaith
Energy Environ. Sci., 2014, Accepted Manuscript
DOI: 10.1039/C4EE01076K

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