3M nanostructured thin film

M Nanostructured Thin Film as Support Materials for Fuel Cells 159... 

The 3M nanostructured thin film (NSTF) catalyst support has also been well developed, which consists of oriented, nanometer-sized crystalline organic whiskers, synthesized by sublimation and subsequent annealing of an organic... 

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]. 

Increase surface area of the 3M-patented, nanostructured, thin film catalyst support system consistent with high volume manufacturing process. 

The 2007 cost of 67/kW is based on a new design by the 3M Company, which utilizes 3M s nanostructured thin film (NSTF) catalyst support for the cathode (Ahluwalia et ah, 2007 Lasher et ah, 2007). The cathode uses the bulk of the platinum. NSTF (apparently a carbon fabric ), in conjunction with vacuum deposition of an iron-cobalt-carbon-nitrogen cathode catalyst followed by a heat treatment, has apparently been successful in cutting the platinum requirement by more than half while increasing performance (3M Company, 2007). The research team at 3M is also optimistic about production costs. 

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. 

A new catalyst systan developed by 3M called Nanostructured Thin Film (NSTF) is the first practical example that managed to find a delicate balance by utilizing the... 

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. 

Another milestone in performance was achieved with the nanostructured thin-film technology of catalyst layer fabrication, developed by Mark K. Debe at the company 3M (Debe et al., 2006). With this innovative approach, mpt could be reduced by another order of magnitude at the critical cathode side, while performance is maintained and catalyst durability and lifetime are in fact significantly enhanced. 

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