Archive for the ‘Inorganic’ Category

A cloak of many carbons

Catalysts can be exceedingly useful in the real world, from treating our car’s exhaust fumes to creating fertilisers.  There are many ways to make catalysts and even multiple ways to make the same catalyst.  The path that you choose to a catalyst can have a significant impact on the quality of the end product.

Eloy del Rio and team from the Structure and Chemistry of Nanomaterials group at the University of Cadiz in Spain have investigated ceria-based oxide-supported gold catalysts for carbon monoxide oxidation.  The routine for depositing the metal phase onto the oxide support and the subsequent catalyst activation step can ultimately affect the activity of the catalyst.  Catalysts prepared by deposition-precipitation with urea followed by activation under oxidising conditions result in significantly more activity than those prepared under reducing conditions.

Variation in catalyst activity under oxidising and reducing activation protocols.

This had previously been observed by others, but the reason for the difference was never discussed.  The authors set out to find out why the activity differed.  They used a suite of nano-analytical and nano-structural techniques to probe the catalysts, finding that the catalyst prepared under reducing conditions had a coat of amorphous carbon which severely hampered the catalyst activity.  This could be removed by a re-oxidation treatment that burnt away the carbon layer and produced an active catalyst similar to the one produced under oxidising conditions.

The precipitating agent used in the synthesis can also influence the resulting activities of catalysts prepared via the deposition-precipitation method.  No difference between oxidising and reducing activations is observed when sodium carbonate is used in place of urea.

To read the details, check out the ChemComm article in full:

Dramatic effect of redox pre-treatments on the CO oxidation activity of Au/Ce0.50Tb0.12Zr0.38O2-x catalysts prepared by deposition-precipitation with urea: a nano-analytical and nano-structural study
E. del Rio, M. López-Haro, J.M. Cies, J.J. Delgado, J.J. Calvino, S. Trasobares, G. Blanco, M.A. Cauqui and S. Bernal
Chem. Commun., 2013, 49, Accepted Manuscript
DOI: 10.1039/C3CC42051e

Iain Larmour is a guest web writer for ChemComm.  He has researched a wide variety of topics during his years in the lab including nanostructured surfaces for water repellency and developing nanoparticle systems for bioanalysis by surface enhanced optical spectroscopies.  He currently works in science management with a focus on responses to climate change.  In his spare time he enjoys reading, photography and art.

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ChemComm-RSC Prizes and Awards Symposium: Supramolecular Chemistry

Last month we were delighted to hold a ChemComm-RSC Prizes and Awards Symposium on supramolecular chemistry at Trinity College Dublin, Ireland. The free one-day event was a great success, with over 160 delegates and a fantastic programme featuring RSC Award winners and leaders in the field.

CC supramolecular symposium

Speakers from the ChemComm-RSC Prizes and Awards Symposium on Supramolecular Chemistry, 24 May 2013, Dublin, Ireland

Speakers included:

  • Jerry Atwood, University of Missouri-Columbia – Winner of the 2012 RSC Supramolecular Award
  • John Callan, University of Ulster
  • Chris Chang, University of California, Berkeley – Winner of the 2012 RSC Chemistry of Transition Metals Award
  • Sylvia Draper, Trinity College Dublin
  • Phil Gale, University of Southampton – ChemComm sponsored lecture
  • David Leigh, University of Manchester – ChemComm sponsored lecture
  • Donal O’Shea, University College Dublin
  • Susan Quinn, University College Dublin
  • Eoin Scanlon, Trinity College Dublin
  • Jonathan Steed, Durham University – ChemComm sponsored lecture

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It’s getting hot in here…

Stimuli-responsive nanoparticles are the focus of much current research, and what could be better than a nanoparticle that responds to one stimulus?  A nanoparticle which responds to two or three.

Xianmao Lu and his team have coupled plasmonic silver nanoparticles to magnetic iron oxide nanoparticles and wrapped both in a thermoresponsive polymer – poly(n-isopropylacrylamide).

When illuminated by sunlight the silver nanoparticles absorb the light and convert it to heat.  The increase in temperature causes the polymer wrapping to collapse and reduces steric repulsion between the nanoparticle dimers leading to clustering.

Sunlight induced clustering of Magnetic-Plasmonic Heterodimers.

This clustering enhances the magnetic separation of the very small dimers from the solution (the nanoparticles are less than 9 nm each).  When you’ve caught the nanoparticles and are done with them, you can turn the lights off and they will re-disperse.

Don’t worry if you live in a cloudy part of the world, you can use a solar simulator to induce the clustering.  It would probably be easier to turn off than the sun, too.

To read the details, check out this HOT Chem Comm article in full:
Thermoresponsive Nanoparticles + Plasmonic Nanoparticles = Photoresponsive Heterodimers: Facile Synthesis and Sunlight-Induced Reversible Clustering
Hui Han, Jim Yang Lee and Xianmao Lu
Chem. Commun., 2013, 49, Accepted Manuscript
DOI: 10.1039/C3CC42273A

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Photocatalysis in a nanocup

Written by Geoff Nelson, web writer.

Nanocups of anatase TiO2 coated with Au nanoparticles are efficient photocatalysts, as reported in a recent ChemComm article by Chemical Science and Chem Soc Rev Advisory Board member Jinlong Gong and  his group at Tianjin University, China.

This new shape promises to increase reactive surface area by exposing the normally inaccessible surface of hollow spheres.  Compared to TiO2 hollow spheres, TiO2 nanocup particles increase the rate of the photocatalytic degradation of methylene blue in the visible light region by 46%.

This performance and the ease of nanocup synthesis are reasons to promote further research.  Thus, we may expect nanocups made from other metal oxides and inorganic materials to be incorporated into solar, photochemical, and catalytic applications in the future.

In addition, the ability of nanocups to confine small amounts of reactants may find utility in nanofluidic devices.

Gong et al.‘s work has recently been highlighted as part of a C&EN article on novel nanostructures.

Read this ChemComm article in full:

Mesoporous anatase TiO2 nanocups with plasmonic metal decoration for highly active visible-light photocatalysis

Jianwei Lu, Peng Zhang, Ang Li, Fengli Su, Tuo Wang, Yuan Liu and Jinlong Gong
Chem. Commun., 2013, Advance Article
DOI: 10.1039/C3CC42029A

Geoff Nelson is a guest web-writer for ChemComm.  He currently works as a post-doctoral research associate in Dr David Payne’s research group in the Department of Materials at Imperial College, London.  Geoff’s current research concerns the synthesis and characterization of post-transition metal oxides for use in the energy sector.  His other research interests include carbon-based materials, biophysical chemistry, and surface science.

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ChemComm Emerging Investigator Lectureship 2013: Winners Announced

louise

Louise Berben

On behalf of the ChemComm Editorial Board we are delighted to announce the winners of the ChemComm Emerging Investigator Lectureship 2013.

Marina Kuimova

Marina Kuimova

This year we received a high number of excellent nominations and therefore the Editorial Board have decided to award two Emerging Investigator Lectureships in 2013. The winners are Professor Louise A. Berben (University of California Davis, USA) and Dr Marina Kuimova (Imperial College London).

This annual lectureship recognises an emerging scientist in the early stages of their independent academic career.

The Editorial Board commended Louise’s contributions to the field of synthetic and physical inorganic chemistry, and Marina was awarded the lectureship for her excellent work within biophysical chemistry. Further details of the two Lectureships, including lecture locations, will be announced soon.

To find out more about the winners’ research, read some of their latest articles in ChemComm:

Redox active aluminium(III) complexes convert CO2 into MgCO3 or CaCO3 in a synthetic cycle using Mg or Ca metal
Thomas W. Myers and Louise A. Berben
Chem. Commun., 2013, DOI: 10.1039/C2CC37208H

Simple routes to bulky silyl-substituted acetylide ligands and examples of V(III), Fe(II), and Mn(II) complexes
Gereon M. Yee, Kristin Kowolik, Shuhei Manabe, James C. Fettinger and Louise A. Berben
Chem. Commun., 2011,47, 11680-11682, DOI: 10.1039/C1CC14758G

Reactive oxygen species in photochemistry of the red fluorescent protein “Killer Red”
Russell B. Vegh, Kyril M. Solntsev, Marina K. Kuimova, Soohee Cho, Yue Liang, Bernard L. W. Loo, Laren M. Tolbert and Andreas S. Bommarius
Chem. Commun., 2011,47, 4887-4889, DOI: 10.1039/C0CC05713D

Also of interest: You can now browse the 2013 Emerging Investigators Issue – which features research from outstanding up-and-coming scientists

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ChemComm-RSC Prizes and Awards Symposium: Supramolecular Chemistry

We invite you to join us for the ChemComm-RSC Prizes and Awards Symposium which will be taking place on 24 May 2013 in Dublin, Ireland.

This free one-day event will comprise of stimulating lectures reflecting the academic and industrial breadth of supramolecular chemistry, delivered by RSC Prize and Award winners and leaders in the field.

Confirmed Speakers:

  • Jerry Atwood, University of Missouri-Columbia – Winner of the 2012 RSC Supramolecular Award
  • John Callan, University of Ulster
  • Chris Chang, University of California, Berkeley – Winner of the 2012 RSC Chemistry of Transition Metals Award
  • Sylvia Draper, Trinity College Dublin
  • Phil Gale, University of Southampton – ChemComm sponsored lecture
  • David Leigh, University of Manchester – ChemComm sponsored lecture
  • Donal O’Shea, University College Dublin
  • Susan Quinn, University College Dublin
  • Eoin Scanlon, Trinity College Dublin
  • Jonathan Steed, Durham University – ChemComm sponsored lecture

We hope you and your colleagues will be able to attend the ChemComm-RSC Prizes and Awards Symposium. For further information about this event and to register, please visit the dedicated webpage.

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Nitrogen-containing graphene-like structures: Theory and experiment combine to reveal active sites

There is significant interest in nitrogen-containing electrocatalysts, driven by the need to find cost-effective and efficient material solutions for replacing platinum in polymer electrolyte membrane fuel cells.  However, the active sites of non-platinum group metal, oxygen reduction reaction electrocatalysts have been contentious for over 50 years.

Fortunately researchers are agreed that Metal(Me)-Nx centres may serve as possible active sites but whether it is Me-N2 or Me-N4 remains unresolved.  X-ray Photoelectron Spectroscopy (XPS) would be the ideal technique to answer this question if it didn’t rely on the use of reference spectra; none exist for the Me-N2 species which makes it less than ideal.

Fitting of DFT calculated curves to experimental results.

Kateryna Artyushkova, Plamen Atanassov and their team have overcome this problem by using density functional theory (DFT) to calculate the binding energy shifts of the species.  Calculating the binding energy shifts, rather than just the binding energies, allows the team to overcome the challenges associated with DFT calculations including; treatment of the core electrons and the poorly screened Coulomb potential near the nucleus.

Once validated, the DFT output can be used as input for XPS curve fitting.  This has revealed rearrangement around Cobalt-Nx centres in an oxidizing atmosphere and supports the understanding of these catalysts as vacancy-and-substitution defects in a graphene-like matrix.

This work demonstrates the synergy between experiment and theory which allows critical information to be extracted that might otherwise remain hidden.

For more, read this ChemComm article in full:

Density functional theory calculations of XPS binding energy shift for nitrogen-containing graphene-like structures
K. Artyushkova, B. Kiefer, B. Halevi, A. Knop-Gericke, R. Schlogl and P. Atanassov
Chem. Commun., 2013, 49, 2539-2541
DOI: 10.1039/C3CC40324F

Iain Larmour is a guest web-writer for ChemComm.  He has researched a wide variety of topics during his years in the lab including nanostructured surfaces for water repellency and developing nanoparticle systems for bioanalysis by surface enhanced optical spectroscopies.  He currently works in science management with a focus on responses to climate change.  In his spare time he enjoys reading and photography.

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X-ray nanoscopy of cobalt Fischer–Tropsch catalysts at work

Cobalt Fischer–Tropsch catalysts have been investigated in both 2-D and 3-D, by scientists in the Netherlands and the US, using in situ hard X-ray transmission X-ray microscopy (TXM). The FischerTropsch process is an important step in the production of liquid fuels from natural gas, biomass or coal.

Tomographic elemental mapping revealed the 3-D distribution of cobalt over the catalyst particles showing that cobalt is heterogeneously concentrated in the centre of the catalyst particles. 2-D chemical mapping allowed them to follow the chemical composition of the catalyst particles under reaction conditions.

This is the first time that this particular catalyst has been observed at the single particle level under reaction conditions, allowing the team to get a true picture of the deactivation of the catalyst which will provide information to help improve the catalyst’s productivity.

‘HOT’ Communication – read for free today:

X-ray Nanoscopy of Cobalt Fischer-Tropsch Catalysts at Work
Korneel Cats , Inés González-Jiménez , Yijin Liu , Johanna Nelson , Douglas van Campen , Florian Meirer , Ad M.J. van der Eerden , Frank M F de Groot , Joy C. Andrews and Bert Weckhuysen
Chem. Commun., 2013, DOI: 10.1039/C3CC00160A

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Ready to order? Yes, I’ll have the extra cold superconducting penne, please…

Written by guest web-writer Kevin Murnaghan.

In this highly original work, researchers from the Complex Functional Materials Group at the University of Bristol and the Superconductivity and Magnetism Group at the University of Warwick have used off-the-shelf, supermarket pasta as a sacrificial template for the production of a variety of superconducting wires, tubes and spirals.  They have even made a superconducting ‘jolly roger’ skull and crossbones.

Here’s how: The pasta was pre-washed to remove impurities and then rehydrated in a solution containing a mixture of nitrates of yttrium, barium and copper. A slight excess of barium nitrate was used to make sure the desired superconducting material YBa2Cu2O7-x phase (Y123) was attained. Via a calcination process the superconducting pasta shapes were produced, removing the organic material of the sacrificial template and neatly retaining the macroscopic shape of the template.

C3CC38271K_graphical abstract

‘Chemical black pepper and parmesan’ were provided by the use of silver nitrate in the process, which boosts electrical and structural properties. Without using this salt, structures formed are brittle, but with it, compressive strength of the shapes doubled in strength from 0.76 to 1.56 MPa.  This helped counteract the effect of porosity formed from the outgassing of the sacrificial pasta during the calcination process.

Interestingly, the pasta had its own influence on the properties of the material.  Starch-mediated reduction of Ag(I) to Ag(0) is the reason for the dark colour of the materials formed, and trace transition metals in the foodstuff were found to have an effect on electrical and superconducting properties.

Critical temperatures, Tc and current densities, Jc, in early samples were found to be low, relative to typical Y123 type superconductors when silver was not included in the synthesis, and were markedly improved when it was.  Further improvements to the superconductivity of the spaghetti-based replicas were achieved via sintering and annealing.  This work represents a highly cost-effective route to a range of superconducting materials with macroscopic architectures, compared with current state of the art processes such as CVD or PLD.  Future work will focus, in part, on further densification of the product, and purity of the sacrificial template.  Further fascinating information is provided in the electronic supplementary information.  Buon appetito!

C3CC38271K_coverRead this ChemComm cover article today:

Designed 3D architectures of high-temperature superconductors

David C. Green, Martin R. Lees and Simon R. Hall
Chem. Commun., 2013,49, 2974-2976
DOI: 10.1039/C3CC38271K

Kevin Murnaghan is a guest web-writer for Chemical Communications. He is currently a Research Chemist in the Adhesive Technologies Business Sector of Henkel AG & Co. KGaA, based in Düsseldorf, Germany. His research interests focus primarily on enabling chemistries and technologies for next generation adhesives and surface treatments. Any views expressed here are his personal ones and not those of Henkel AG & Co. KGaA.

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Penny Brothers joins ChemComm as Associate Editor

ChemComm warmly welcomes Professor Penny Brothers (University of Auckland, New Zealand) as a new Associate Editor. 

Penny Brothers is now accepting submissions to ChemComm in the areas of porphyrin chemistry, the main group elements and organometallic chemistry.  Her current research interests also include the chemistry of new sustainable materials and inorganic medicinal chemistry. 

Submit your next top-notch, high-impact Communication to Penny Brother’s Editorial Office.

Biography

Penny Brothers was born and grew up in Auckland, New Zealand, and completed her BSc and MSc(Hons) degrees in chemistry at the University of Auckland.  In 1979 she was awarded a Fulbright Fellowship and set off for Stanford University to begin a PhD in chemistry under the supervision of Professor Jim Collman.  Her PhD thesis, and much of her subsequent research work, has centered around the chemistry of porphyrin complexes.Professor Penny Brothers

In 1986 she returned to Auckland and spent two years working as a postdoctoral fellow with Professor Warren Roper in the Department of Chemistry, focussing on organometallic chemistry.  In 1988 she took up her current academic position at the University of Auckland.

She has been a visiting scientist at Los Alamos National Laboratory (2003, 2005, 2006) and a visiting professor at the University of California at Davis (1993), the University of Heidelberg (2003) and the University of Burgundy (2004, 2006).  She has been awarded a Fulbright Senior Scholar Award for 2007.

Her current research brings together her interests in porphyrin chemistry, the main group elements and organometallic chemistry.  She investigates how the porphyrin ligand can be used to modify the chemistry of elements such as boron and bismuth, and as a ligand in complexes containing unusual chemical bonds between transition metal and main group elements.  She has a number of research collaborations in NZ and internationally.

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