Nanostructured thin-film electrodes

The nanostructured thin-film electrode was first developed at 3M Company by Debe et al. [40] and Debe [41], who prepared thin films of oriented crystalline organic whiskers on which Ft had been deposited. The film was then transferred to the membrane surface using a decal method, and a nanostructured thin-film catalyst-coated membrane was formed as shown in Figure 2.10. Interestingly, both the nanostructured thin-film (NSTF) catalyst and the CL are nonconventional. The latter contains no carbon or additional ionomer and is 20-30 times thinner than the conventional dispersed Pt/ carbon-based CL. In addition, the CL was more durable than conventional CCMs made from Pt/C and Nation ionomer [40]. 

So, under such a circumstance, only when the combined thickness of the GDM and the CL is around 0.11 pm will the diffusion of O2 be enough to support a current density of 1.5 A cm Therefore, under a completely flood condition, an actual fuel cell with a combined thickness of the GDM and the CL of around 300 pm cannot generate a current density of 1.5 A cm" at all. Even for a nanostructured thin film electrode structure developed by 3M with a catalyst layer thickness as thin as 0.5 pm and in the absence of any diffusion medium, it is not possible to provide such a current density if the electrode is completely flooded. 

Figure 2.26 (a) Scheme for an electrostatically self-assembled multilayer (PAHOs)4(Apo-COx)3(COx) electrode, (b) Catalytic current response to p-d-glucose concentration for self-assembled nanostructured thin films of PAH-Os/COx/(PAH-Os/(ApoGOx)3 and (PAH-Os/ApoCOx)3/PAH-Os/COx, where ApoCOx is FAD-free glucose oxidase. Taken from Ref [219]. 

ZnS-CdS (bandgap = 2.3-2.4 eV) composite semiconductor photoelectrodes show a broad spectral response and n-type behavior, with saturation of the anodic photocurrent upon increasing anodic potential making the system suitable for use as a photoelectrochemical cell photoanode [72], Nanostructured ZnS-CdS thin film electrodes show that anodic photocurrent saturation can be attained with the application of a small, 0.1 V, bias [73], while hydrogen evolution is observed at the Pt cathode. The performance of the ZnS-CdS photoanodes appear strongly dependent upon the method of film preparation [72,73], with Zn rich films demonstrating superior photocurrent generation, and stability, in comparison to Cd rich films. 

Figure 12.5 (a) Layer-by-layer deposition of glucose oxidase and the polyallylamine Os3 +n + -polypyridine polyelectrolyte on the electrode, (b) Typical catalytic current responses for different glucose concentrations obtained by self-assembled nanostructured thin films based on different architectures (i) PAH/Os/GOx, (ii) cysteamine/GOx/PAH-Os, (iii) PAH/GOx/ -Os, and (iv) (PAH-Os)2/(GOx)i. All measurements were performed in 0.1 M tris buffer at pH 7.5. Part (b) Reproduced with permission from Ref. 34a. Copyright Wiley-VCH Verlag GmbH Co. KGaA. 

Monllor-Satoca, D., L. Borja, A. Rodes, R. Gomez and P. Salvador (2006). Photoelectrochem-ical behavior of nanostructured W03 thin-film electrodes The oxidation of formic acid. ChemPhysChem, 7(12), 2540-2551. 

Metal oxide nanostructures have been fabricated using different methods and preparation conditions. The most promising technique is sol-gel processing in combination with dipcoating technique.This method enables us to prepare spinel oxide thin film electrodes at ambient temperature with high level of doping and large surface area [117,118], The physical and chemical vapor deposition is another technique for metal oxide preparation [119,120],... 

Developed a roll-good processed electrode backing/gas dilfusion layer component having matched properties to the nanostructured thin film catalyst and flow field generated pilot scale production quantities for statistical analysis of variance and demonstration of process capability. 

A. Solbrand, A. Henningsson, S. Sodergren et al.. Charge transport properties in dye-sensitized nanostructured Ti02 thin film electrodes studied by photoinduced current transients, J. Phys. Chem. B 1999, 103(7), 1078-1083. 

Mendoza-Sanchez, B., T. Brousse, C. Ramirez-Castro, V. Nicolosi, and P. S. Grant. 2013. An investigation of nanostructured thin film a-Mo03 based supercapacitor electrodes in an aqueous electrolyte. Electrochimica Acta 91 253-260. 

Wang, H., Lindgren, T., He, J., Hagfeldt, A., Lindquist, S.-E. Photolelectrochemistry of nanostructured WO3 thin film electrodes for water oxidation mechanism of election transport. J. Phys. Chem. B 104, 5686 (2000)... 

In order to be able to properly examine the inherent activity of minute amounts of OER catalysts, one needs a substrate with minimal interference, extremely slow OER kinetics of its own and extraordinary stability at high positive electrode potentials. The unique featiues of 3M s Pt-NSTF (nanostructured thin film) catalyst [12] such as superior durability, electrochemical inertness at high potentials, and the absence of corrosion interference due to exposed carbrui, made it a logical choice as a support [13, 14]. It is well known that pure platinum has a high overpotential for OER. For instance, at a current density of 1 mA/cm, the OER on platinum proceeds at a potential that is 0.47 V higher than oti single crystal ruthenium oxide [15]. Thus, the OER partial current density oti the Pt-NSTF substrate wiU be orders of magnitudes lower than on ruthenium, iridium, and other similar OER-active materials. 

The last three chapters are dedicated to improving the durability of the catalyst/ electrode. Chapter 22 reports the development and evaluation of bimetallic Pt-Ru (Ir) oxygen evolution catalysts on 3M s nanostructured thin film (NSTF). This type of catalyst may significantly reduce carbon corrosion and Pt dissolution during transient conditions of fuel cells. Chapter 23 discusses the unique properties of carbide-modified carbon as the support for fuel cell catalysts. The final chapter gives a comprehensive review of novel materials other than carbon black as catalyst support. The interactions between the supports and catalysts are intensively discussed in the last two chapters. 

On the other hand, different forms of doped diamond-like materials, particularly boron-doped diamond (BDD), have been widely employed as electrode materials in the form of (nanostructured) thin films [162]. The use of these materials in electroanalysis exploits the wide potential window (Fig. 6.16), chemical inertness, mechanical robustness, and small background current typical of this class of materials. 

Nanostructured Thin Film (NSTF) Electrode. Debe et al. [59, 60] employed sputter technology and deposited catalyst on a nanostructured thin film (NSTF). This NSTF is an oriented crystalline organic whisker. Perylene red (PR) is a highly useful organic material for growing the NSTF. To form an electrode, the... 

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