EES Blog

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.

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

Energy and Environmental Science author Aaron Wheeler (University of Toronto) was recently interviewed in Chemistry World about his recent paper describing a technique that can screen algae with the aim of generating more efficient biofuels.

Here’s the beginning of the interview:

You recently reported an exciting technique that can screen algae grown under different wavelengths with the aim of generating more efficient biofuels.¹ Can you tell me more about this work?

Sure, this was the first time we have developed a method for the area of renewable energy. I had a student, Steve Shih, who is now a postdoc at the Joint BioEnergy Institute in California, who became interested in the idea that we can cultivate algae to produce biofuel. Of course this is an idea that has been around for a while.

So, in looking at the problem it seems that the biofuel we can collect from algae does not have the required energy density relative to the cost needed to extract and generate fuel, to compete with non-renewable resources. There are ongoing efforts to develop ways to encourage algae to generate more lipids. The idea is that the algae generate stores of lipids that we can then extract and refine into fuel.

We saw an opportunity; we thought we might be able to build a microfluidic device that could rapidly screen for conditions that folks haven’t looked at before just to see if we could find some conditions that encouraged the algae to produce more lipids. A lot of time we start these projects but don’t end up with an exciting result, but this one was really exciting in that we believe we have identified a brand new phenomenon which is that, at least for this particular algae, if you culture them under yellow light they experience some sort of stress which causes them to increase lipid production!

Visit Chemistry World now to read the rest!

1. S C C Shih et al, Energy Environ. Sci., 2014, 7, 2366 (DOI: 10.1039/c4ee01123f)

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.

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

Researchers in China have used human hair to make a vital component of energy-storage devices. The discovery could lead to more efficient and environmentally-friendly replacements for traditional batteries.

Many batteries currently in use, such as the lead–acid batteries in cars, are heavy and bulky and rely on hazardous chemicals to store electrical charge. With increasing worldwide sales of mobile electronics, the environmental impact of batteries is receiving more attention and motivating research into supercapacitors, which can be made from sustainable carbon-based materials.

Unfortunately, these carbon materials are usually either difficult to manufacture or derived from fossil fuels. Now, however, Feng Yan and his team at Soochow University have used a simple carbonisation process to turn human hair – a common and renewable waste product – into carbon flakes suitable for use in supercapacitor electrodes.

Interested to know more? Read the full news article by Stephan McCarthy in Chemistry World here…

Read the article by Wenjing Qian et al. in EES:

Human Hair-Derived Carbon Flakes for Electrochemical Supercapacitors
Wenjing Qian, fFengxia Sun, Yanhui Xu, Lihua Qiu, Chang-Hai Liu, Sui-Dong Wang and Feng Yan
Energy Environ. Sci., 2013, Accepted Manuscript
DOI: 10.1039/C3EE43111H, Paper