Bacteria provide template for oxide nanostructures with strong electrochemical performance; potential applications in batteries, catalysts, sensors and supercapacitors
19 December 2010
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| (a) Schematic diagram of the bacteria-templated synthesis of the oxide nanostructures. Typical FESEM images of (b) the pure bacteria, (c) the bacteria/cobalt oxide rods, and (d) the hollow cobalt oxide rods. The insets depict the cross section of each sample. Credit: ACS, Shim et al. Click to enlarge. |
Researchers at Ajou University, South Korea, have developed a simple, high-yield biomineralization process to create cobalt oxide nanostructures with a high surface area using Bacillus subtilis bacteria as soft templates. The nanostructures resulting from this synthesis process can be used in a range of practical applications such as batteries, catalysts, sensors and supercapacitors, according to the team in a paper published 14 December in the journal ACS Nano.
In this work, the team prepared rod-type cobalt oxide (Co3O4) nanostructures at room temperature through an electrostatic interaction between the functional surface structures of the bacteria and the cobalt ions in an aqueous solution. Porous cobalt oxide hollow rods were then formed through a subsequent heat treatment at 300 °C.
The resulting nanorods has a high surface area of 73.3 m2 g-1, and exhibited an enhanced Coulombic efficiency as well as reversible specific capacity of 903 mAh g-1 after 20 cycles.
Templating is a well known and versatile technique for the construction of advanced materials with controlled structures. Templating can use either hard templates (such as anodized alumina membranes and MCM-41 silica) or soft templates (such as surfactants and block co-polymers.
More recently, one type of soft templates, biological templates (bacterium, DNA, virus particles, etc.), has been used to deposit nanoparticles and produce unique nanostructures. Comparatively, bacteria could be promising in the generation of a variety of unique inorganic structures on the micro- or even nanoscopic level, through the combination of traditional chemical techniques without stringent genetic engineering. These structures could possibly be used for the facile, large-scale production of functional materials.
—Shim et al.
B. subtilis is a Gram-positive bacterium the surface of which features metal-binding properties. Using the aqueous electroless deposition procedures, the team fabricated cobalt oxide nanostructures that retained the shape of the bacterial template.
Resources
Hyun-Woo Shim, Yun-Ho Jin, Seung-Deok Seo, Seung-Hun Lee, and Dong-Wan Kim (2010) Highly Reversible Lithium Storage in Bacillus subtilis-Directed Porous Co3O4 Nanostructures. ACS Nano, Article ASAP doi: 10.1021/nn1021605
Very interesting approach. Let's see if it can be scaled up and produce at an affordable cost.
Posted by: HarveyD | 19 December 2010 at 06:07 PM