November 2011 – Chemical Communications Blog

Archive for November, 2011

Scattering layer for dye-sensitised solar cells

28 Nov 2011

We are all aware how important it is to find new improved ways to generate sustainable energy. One very promising candidate is the dye-sensitised solar cell which is particularly attractive due to its low production cost and mechanical robustness.

Scientists from East China Normal University have found a way to increase the efficiency of dye-sensitised solar cells by introducing an additional layer on top of the TiO₂ photoanode. The extra layer, made up of Y₃Al₅O₁₂:Ce down-converting microparticles, causes the conversion efficiency to increase from 6.97% to 7.91%.

SEM image of the Y₃Al₅O₁₂:Ce layer and the J-V curves for the solar cell with and without the additional layer

Likun Pan and his team have attributed this improved performance to the increased light absorbing and scattering properties of the microparticle layer (meaning more suitable photons are available for absorption by the dye) and reduced electron transfer resistance.

Download the ChemComm article to read more about the fabrication of Pan’s solar cell device.

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REMINDER: Approaching deadline for ChemComm Emerging Investigator Lectureship

28 Nov 2011

***DEADLINE FOR NOMINATIONS: 9th DECEMBER 2011***

We are delighted to invite nominations for the 2^nd ChemComm Emerging Investigator Lectureship. The lectureship, which is awarded annually, will recognise an emerging scientist in the early stages of their independent academic career.

To qualify
To be eligible for the ChemComm Emerging Investigator Lectureship, the candidate should have completed their PhD on or after 5th September 2003.

The candidate should also have published at least one article in ChemComm during the course of their independent career.

Award details
The recipient of the award will be invited to present a lecture at three different locations over a 12 month period. It is expected that at least one of the locations will be a conference. The recipient will receive a contribution of £1500 towards travel and accommodation costs. S/he will also be presented with a certificate and be asked to contribute a ChemComm Feature Article.

Nominations
Those wishing to make a nomination should send the following details to the ChemComm Editorial Office by 9th December 2011:

Recommendation letter, including the name, contact details and website URL of the nominee.
A one page CV for the nominee, including their date of birth, summary of education and career, list of up to five independent publications, total numbers of publications and patents and other indicators of esteem and evidence of independence.
A copy of the candidate’s best publication to date (as judged by the nominator).
Two supporting letters of recommendation from two independent referees. These should not be someone from the same institution or the candidate’s post doc or PhD supervisor.

The nominator and independent referees are requested to comment on the candidate’s presenting skills.

Please note that self nomination is not permitted.

Selection procedure
The ChemComm Editorial Board will draw up a short-list of candidates based on the information provided by the referees and nominator. Short-listed candidates will be asked to provide a supporting statement justifying why they deserve the award. The recipient of the award will then be selected and endorsed by the ChemComm Editorial Board.

Previous winner
2011 Dr Scott Dalgarno (Heriot-Watt University, Edinburgh, UK) – Find out about his Emerging Investigator Lecture tour in China

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Catalyst to wash tarnished metals in industry

24 Nov 2011

A simple and cheap way to clean tarnished metals using a UV activated photocatalyst ink has been developed by UK scientists. Removing steel corrosion is a major concern in many industries. Most metals are thermodynamically unstable in air and aqueous solution but owe their durability to metal oxides that form on the surface. However, when the metal oxides thicken, it leads to contamination with undesirable corrosion products that need to be removed. Aggressive chemicals such as strong acids and chelating agents are usually required to remove them.

The photocatalyst ink was applied to the tarnished metal and then UV light was shone onto it. This produced conduction band electrons and valence band holes. An electron donor species in the ink reacted with the holes, leaving the photogenerated electrons to react with absorbed metal ions. The metal oxide layer could then be removed with water.

: Photographs of an annealed stainless steel coupon without (A) and with (B) a rectangle of the inks cast on its surface. UVA irradiation of sample B through a brass ‘TiO2’ template (C) revealed an image of the ‘TiO2’ template on the coupon, (D)

Reference:
Photocatalyst film and ink for cleaning tarnished metals
A Mills and D Hazafy, Chem. Commun., 2011
DOI: 10.1039/c1cc15774d

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One nanoparticle, two nanoparticles, three nanoparticles, four!

22 Nov 2011

Nanoparticles might be small but they frequent the pages of many a journal due to the ongoing boom in nanotechnology research. Whilst they are useful in a myriad of fields, it is still difficult to directly characterise these extraordinarily small entities. King among the visualisation techniques is electron microscopy but this often requires the isolation of the sample on a support – hardly sufficient for analysing a dynamic sample in solution! Dynamic light scattering is another potential technique but finds limitations when it comes to much smaller nanoparticle sizes.

Ideally, you want to be able to count and size individual nanoparticles at a rate which produces reliable statistics. To address this challenge, Richard Compton and his team, including Neil Rees and Yi-ge Zhou who conducted the experiments alongside Jeseelan Pillay, Robert Tshikhudo and Sibulelo Vilakazi from Mintek, Randburg, have used anodic particle coulometry (APC) to measure gold nanoparticle collisions with a glassy carbon microelectrode and thus count and size individual nanoparticles.

With the electrode potential set above +1.0 V, they were able to record oxidative Faradaic transients from nanoparticle collisions and calculate an average nanoparticle radius which compared extremely well to the radius obtained from scanning electron microscopy measurements. They were also able to observe nanoparticle aggregation, which holds great promise for monitoring dynamic aggregation reactions.

It shouldn’t be long before this technique is routinely used to gain more information on all sizes of metallic nanoparticles which are currently being used in a variety of applications.

Read the ChemComm article by Compton and team for more.

Posted on behalf of Iain Larmour, web science writer for ChemComm.

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Super-fast crystals

22 Nov 2011

Identification of all solid forms of a pharmaceutical is important for drug delivery, due to the potential variability in the physical and chemical properties between amorphous and crystalline forms. The amorphous form of a compound is typically more soluble, but less stable than its crystalline counterpart. Not only that but different polymorphs of the crystalline compound can also have significantly different properties. To accurately characterise drug action, these polymorphs need to be identified.

Using small-scale crystallisation and in-situ Raman spectroscopic analysis of the antihypertensive drug, nifedipine, Franziska Emmerling and colleagues discovered an extraordinarily fast transition from the glassy amorphous state to the metastable β polymorph in less than a minute. The β polymorph is stable for less than ten minutes before transforming again, to the thermodynamically stable α polymorph.

The speed at which the transformations take place implies that classical diffusion is not responsible for the different polymorphs but could instead be the result of small intramolecular changes arising from a pre-ordered physical arrangement of the molecules.

In an industrial world where screening for solid drug forms is always leaning towards scale-reduction and time-reduction, three physical forms on a glass slide in less than twenty minutes is pretty impressive!

To find out more, download the ChemComm article.

Also of interest… Read Andrew Bond, U. Ramamurty, and Gautam Desiraju’s Chemical Science article on “Interaction anisotropy and shear instability of aspirin polymorphs established by nanoidentation“.

Posted on behalf of Scott McKellar, web science writer for ChemComm.

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40 days until 100 issues…

22 Nov 2011

….and did you know….?

In 2005, ChemComm published a series of Focus Articles to celebrate its 40th anniversary. In the first Focus Article, Bert Meijer reviewed the career of Hans Wynberg, the author of the first ever ChemComm paper back in 1965. Coincidentally, Bert Meijer was the author of the first ever Chemical Science article in 2010.

Focus Articles aren’t the only ‘special’ article type to be published ChemComm. This year we’ve published a series of Highlights in Chemistry to celebrate the International Year of Chemistry. And next year, to celebrate our move to 100 issues, we’ll be introducing some exciting new content – stay tuned for our issue 1, 2012 Editorial to find out more!

Also of interest:
100 days to 100 issues
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43 days until 100 issues…

18 Nov 2011

….and did you know….?

43 is the number of cookies Editor Robert Eagling brought in to celebrate his last birthday. He assured us that this number was in no way linked to his age.

Also of interest
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44 days until 100 issues…

18 Nov 2011

….and did you know….?

ChemComm currently has 44 Advisory Editorial Board members, who, aside from being world-leading scientists, represent and promote ChemComm and advise the Editorial Board and authors on scientific matters. To find out who they are, visit the journal website.

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Hybrid biofuel cell

16 Nov 2011

Scientists from Israel have designed a biofuel cell that combines the advantages of both enzymatic and microbial fuel cells.

Biofuel cells use redox enzymes to convert chemical energy into electricity. These cells can be divided into two categories: enzymatic fuel cells which require the enzymes to be purified and microbial fuel cells which make use of an entire microorganism. There are pros and cons to both strategies – enzymatic fuel cells tend to have increased power output whilst microbial fuel cells enable full oxidation of a wider range of fuels.

Yet now, Lital Alfonta and co-workers demonstrate that by designing a hybrid cell, one can have the best of both worlds. The team have modified yeast to display redox enzymes on their surface and then introduced this into both the anode and cathode compartments. This approach removes the need to purify the enzymes and enables regeneration of both fuel compartments.

To find out more about Alfonta’s biofuel cell device, read the ChemComm article today.

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Nitron, the new N-heterocyclic carbene

15 Nov 2011

N-heterocyclic carbenes (NHCs) are extremely useful reagents in synthesis and catalysis, but unfortunately they are expensive with 1 gram costing several hundred US dollars.

However, as Ulrich Siemeling and his colleagues report in their latest ChemComm, it seems that a much cheaper alternative is on the horizon…

The team of scientists based at the University of Kassel have discovered that Nitron, a low cost analytical reagent, exhibits surprising NHC reactivity, more akin to that of its tautomeric form than its conventional Lewis structure. By reacting Nitron with typical carbene trapping reagents such as elemental sulphur, CS₂, and rhodium complexes, they have proven that it is indeed Nitron’s tautomer that it responsible for its NHC-like reactivity in solution, despite being present at concentrations undetectable by NMR spectroscopy.

At a fraction of the price and already commercially available, Nitron may soon become a very popular choice in NHC reactions.

To read more about how Siemeling and co-workers established the cause for Nitron’s unusual reactivity, download the ChemComm article.

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Chemical Communications Blog

Archive for November, 2011

Scattering layer for dye-sensitised solar cells

REMINDER: Approaching deadline for ChemComm Emerging Investigator Lectureship

Catalyst to wash tarnished metals in industry

One nanoparticle, two nanoparticles, three nanoparticles, four!

Super-fast crystals

40 days until 100 issues…

43 days until 100 issues…

44 days until 100 issues…

Hybrid biofuel cell

Nitron, the new N-heterocyclic carbene

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