Archive for September, 2017

Synthesis of Tin Dioxide Nanotubes for Lithium-ion Batteries with “A Grain of Oxalate Salt”

Preparation of tube-shaped electrode materials for lithium-ion batteries is a trending topic. Tubes with hollow cylindrical bodies allow exposure of the electrodes’ interior surface and can accommodate the large volumetric expansion commonly observed when lithium ions diffuse (either via intercalation or alloying) into the electrodes. The aforementioned two characteristics improve the specific capacity (a measure of how much electric energy one electrode can hold) and lifetime of electrodes.

Recently, the Mai research group from Wuhan University of Technology, China demonstrated a straightforward method for the synthesis of tin dioxide nanotubes as high-performance anodes for lithium-ion batteries. They adopted manganese(III) oxyhydroxide (MnOOH) nanowires as the sacrificial templates and immersed them in a batch of aqueous solutions containing tin(II) cations and oxalate anions (C2O42-). Afterwards, they warmed the mixture at 60 oC under constant magnetic stirring for 4 h and collected a white precipitate consisting of tin dioxide nanotubes. These nanotubes were then washed and coated with carbon thin films to improve their electrical conductivity and structural stability before being subjected to performance evaluations.

The presence of oxalate anions was crucial for producing the nanotubes with a well-defined shape. The function of these anions was revealed through a series of experiments. Oxalate anions first reduced MnOOH to manganese(II) cations and consumed protons in the vicinity of the MnOOH surface. The consumption of local protons increased the local pH and triggered precipitation and oxidation (by dissolved oxygen) of Sn2+ to tin dioxide. The two reactions proceeded, and eventually the MnOOH nanowires disappeared but tubes of tin dioxide formed around their surfaces (Figure 1). Samples obtained without oxalate salts were irregularly shaped.

Figure 1. (a) The schematic illustration of the synthesis steps of the tin dioxide nanotubes. (b) Scanning electron microscopy and (c) transmission electron microscopy images of the as-prepared tin dioxide nanotubes.

The carbon-coated tin dioxide nanotubes showed superior stability performance to bare tin dioxide nanotubes, as shown from the slower capacity-fading rate depicted in Figure 2a. In addition, carbon coating did not significantly sacrifice nanotubes’ charge-storage performance as both electrodes with and without a coating exhibited comparable capacity at all tested current densities (Figure 2b).

Figure 2. Performance comparison between carbon-coated tin dioxide nanotubes (SnO2@C NTs) and bare tin dioxide nanotubes (SnO2 NTs): (a) long-term stability and (b) capacity achieved at different current densities and charge-discharge cycle numbers.

To find out more please read:

Oxalate-assisted Formation of Uniform Carbon-confined SnO2 Nanotubes with Enhanced Lithium Storage

Chunhua Han, Baoxuan Zhang, Kangning Zhao, Jiashen Meng, Qiu He, Pan He, Wei Yang, Qi Li and Liqiang Mai

DOI: 10.1039/c7cc05406h

About the blogger:

Tianyu Liu is a Ph.D. in chemistry graduated from University of California, Santa Cruz in United States. He is passionate about scientific communication to introduce cutting-edge researches to both the general public and the scientists with diverse research expertise. He is a web blogger for the Chem. Commun. and Chem. Sci. blog websites. More information about him can be found at http://liutianyuresearch.weebly.com/.

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Carbohydrates promoted in new prebiotic theory

It’s plausible that carbohydrates formed on primordial Earth before amino acids. So say UK researchers who have shown that parent molecules to amino acids can catalyse the formation of 2-deoxy-D-ribose, a sugar found in the backbone of DNA.1

Source: Royal Society of Chemistry Amino nitriles can promote the enantioselective aldol reaction of formaldehyde and glycolaldehyde to yield D-glyceraldehyde, and the subsequent reaction of the D-glyceraldehyde with acetaldehyde to make 2-deoxy-D-ribose

We’ll never know the exact process that turned chemistry into biology, but many researchers want to get as close as they can to the truth. Paul Clarke at the University of York is one of those researchers.

Read the full story by Jennifer Newton on Chemistry World.

1 A M Steer et al, Chem. Commun., 2017, DOI: 10.1039/c7cc06083a (This paper is open access.)

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Let single crystals do the heavy lifting

Researchers in the US have developed heat responsive crystalline cantilevers that are capable of lifting a metal ball almost 100 times heavier than the crystal itself.

Stimuli responsive behaviour in soft materials has blossomed in recent years, but for highly crystalline solids, such properties are still surprising, especially for materials that don’t lose their single crystalline nature in the process.

Source: Royal Society of Chemistry
Upon heating, the crystal lattice changes from herringbone packing to infinite 1D chains stacked co-facially along their π surfaces.

Jeremiah Gassensmith and colleagues at the University of Texas at Dallas and the University of North Texas, US, have developed single crystals of an N-substituted naphthalene diimide (NDI) derived organic semiconductor that can undergo a reversible phase change from its α to its β form under heating.

Read the full story by Jason Woolford on Chemistry World.

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HOT ChemComm articles for August

All of the referee-recommended articles below are free to access until 6th October 2017.

Photoactivatable aggregation-induced emission of triphenylmethanol
Yue Zheng, Xiaokun Zheng, Yu Xianga and Aijun Tong
Chem.Commun., 2017, Advance Article
DOI: 10.1039/C7CC04693F, Communication

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Orthogonal switching of self-sorting processes in a stimuli-responsive library of cucurbit[8]uril complexes
Stefan Schoder and Christoph A. Schalley
Chem. Commun., 2017, 53, 9546-9549
DOI: 10.1039/C7CC05469F, Communication

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Condensing the information in DNA with double-headed nucleotides 
Mick Hornum, Pawan K. Sharma, Charlotte Reslow-Jacobsen, Pawan Kumar, Michael Petersena and Poul Nielsen
Chem. Commun., 2017,53, 9717-9720
DOI: 10.1039/C7CC05047J, Communication

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High magnetic relaxivity in a fluorescent CdSe/CdS/ZnS quantum dot functionalized with MRI contrast molecules 
S. G. McAdams, D. J. Lewis, P. D. McNaughter, E. A. Lewis, S. J. Haigh, P. O’Brien and F. Tuna
Chem. Commun., 2017, Advance Article
DOI: 10.1039/C7CC05537D, Communication
This article is part of the themed collection: Commemorating Michael Faraday (1791-1867)

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What [plasma used for growing] diamond can shine like flame?
Michael N. R. Ashfold, Edward J. D. Mahoney, Sohail Mushtaq, Benjamin S. Truscotta and Yuri A. Mankelevich
Chem. Commun., 2017, Advance Article
DOI: 10.1039/C7CC05568D, Feature Article
This article is part of the themed collection: Commemorating Michael Faraday (1791-1867)

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Reversible structural switching of a metal-organic framework by photoirradiation
Varvara I. Nikolayenko, Simon A. Herberta and Leonard J. Barbour
Chem. Commun., 2017, Advance Article
10.1039/C7CC06074B, Communication

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