Carbon characterization/fabrication

P. He and M. Bayachou, Layer-by-layer fabrication and characterization of DNA-wrapped single-walled carbon nanotube particles. Langmuir 21, 6086-6092 (2005). 

As the analytical, synthetic, and physical characterization techniques of the chemical sciences have advanced, the scale of material control moves to smaller sizes. Nanoscience is the examination of objects—particles, liquid droplets, crystals, fibers—with sizes that are larger than molecules but smaller than structures commonly prepared by photolithographic microfabrication. The definition of nanomaterials is neither sharp nor easy, nor need it be. Single molecules can be considered components of nanosystems (and are considered as such in fields such as molecular electronics and molecular motors). So can objects that have dimensions of >100 nm, even though such objects can be fabricated—albeit with substantial technical difficulty—by photolithography. We will define (somewhat arbitrarily) nanoscience as the study of the preparation, characterization, and use of substances having dimensions in the range of 1 to 100 nm. Many types of chemical systems, such as self-assembled monolayers (with only one dimension small) or carbon nanotubes (buckytubes) (with two dimensions small), are considered nanosystems. 

There are a number of informative reviews on anodes for SOFCs [1-5], providing details on processing, fabrication, characterization, and electrochemical behavior of anode materials, especially the nickel-yttria stabilized zirconia (Ni-YSZ) cermet anodes. There are also several reviews dedicated to specific topics such as oxide anode materials [6], carbon-tolerant anode materials [7-9], sulfur-tolerant anode materials [10], and the redox cycling behavior of Ni-YSZ cermet anodes [11], In this chapter, we do not attempt to offer a comprehensive survey of the literature on SOFC anode research instead, we focus primarily on some critical issues in the preparation and testing of SOFC anodes, including the processing-property relationships that are well accepted in the SOFC community as well as some apparently contradictory observations reported in the literature. We will also briefly review some recent advancement in the development of alternative anode materials for improved tolerance to sulfur poisoning and carbon deposition. 

Nanocarbon structures such as fullerenes, carbon nanotubes and graphene, are characterized by their weak interphase interaction with host matrices (polymer, ceramic, metals) when fabricating composites [99,100]. In addition to their characteristic high surface area and high chemical inertness, this fact turns these carbon nanostructures into materials that are very difficult to disperse in a given matrix. However, uniform dispersion and improved nanotube/matrix interactions are necessary to increase the mechanical, physical and chemical properties as well as biocompatibility of the composites [101,102]. 

Jiang, L. and L. Gao, Fabrication and characterization of carbon nanotube-titanium nitride composites with enhanced electrical and electrochemical properties. Journal of the American Ceramic Society, 2006. 89(1) p. 156-161. 

Figure 3.16 Different steps in the fabrication of MWNT nanoelectrode arrays, (a) metal film deposition, (b) catalyst deposition, (c) plasma-enhanced chemical vapor deposition for CNT growth, (d) dielectric encapsulation with Si02, (e) planarization with a chemical mechanical polishing to expose the ends of the carbon nanotubes, (f) electrochemical characterization. Readapted from Ref [6].

Ujiie et al. [204] fabricated quartz chips for NCE and reported the separation of rhodamine B and sulforhodamine at 14.4 and 66.6 cm separator lengths. The buffer was 20 mM phosphate buffer at 2kV applied voltage and the separation was achieved in 70 seconds. Wakida et al. [205] reported a high throughput characterization for dissolved organic carbon in environmental waters within 2 minutes using NCE. The authors collected water samples from 10 sampling points at the Hino River that flows into Lake Biwa. Shin et al. [206] described NCE (PDMS) with fluorescence detection for analyses of atrazine. 

Deki, S., Nabika, H., Akamatsu, K., Mizuhata, M., Kijinami, A., Tomita, S., et.al. (2002) Fabrication and characterization of PAN-derived carbon thin films containing Au nanoparticles, Thin Solid Films 408, 59-63. 

The resolution of SEMs is now suitable for nano-materials characterization. High resolution SEM is a powerful instrument for imaging fine structures of materials and nanoparticles fabricated by nanotechnology. In lens SE, BSE modes, and STEM mode are often performed to check the structure of CNT growths or CNT as delivered by commercial producers, and sometimes coupled with TEM. Even the single-walled carbon nanotubes can easily be observed by HR-SEM (see Figure 3.13). The STEM mode can also be used for free CNT observation (75). 

Li, Y.Y., Bae, S.D., Sakoda, A. and Suzuki, M., 2000, Fabrication and characterization of carbon whisker. The 2nd Pacific Basin Conference on Adsorption Science and Technology, May 14-18, Queensland, Australia, p376-380. 

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