Chemical Communications Blog

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

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.

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 YBa₂Cu₂O_7-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.

‘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, T_c and current densities, J_c, 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!

Read this ChemComm cover article today:

Designed 3D architectures of high-temperature superconductors

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.