High surface area graphite

In redox flow batteries such as Zn/Cl2 and Zn/Br2, carbon plays a major role in the positive electrode where reactions involving Cl2 and Br2 occur. In these types of batteries, graphite is used as the bipolar separator, and a thin layer of high-surface-area carbon serves as an electrocatalyst. Two potential problems with carbon in redox flow batteries are (i) slow oxidation of carbon and (ii) intercalation of halogen molecules, particularly Br2 in graphite electrodes. The reversible redox potentials for the Cl2 and Br2 reactions [Eq. (8) and... 

Catalyst Production. Supported magnetite particles were produced on Grafoll (Union Carbide), a high surface area form of graphite. The nature of Grafoll and the reasons It is convenient to use In MCssbauer spectroscopy experiments eu e described elsewhere (25). Grafoll is also well suited for magnetic susceptibility experiments. 

Various forms of carbon are used to sample those analytes whose breakthrough volume is too low on Tenax for sufficient preconcentration [8,395-399]. Charcoal, graphitized carbon blacks, and ceurbosieves with wface areas from 5 to 900 w /g are commercially availablJ Bhe high surface area sorbents are used... 

A classic definition of electrochemical ultracapacitors or supercapacitors summarizes them as devices, which store electrical energy via charge in the electrical double layer, mainly by electrostatic forces, without phase transformation in the electrode materials. Most commercially available capacitors consist of two high surface area carbon electrodes with graphitic or soot-like material as electrical conductivity enhancement additives. Chapter 1 of this volume contains seven papers with overview presentations, and development reports, as related to new carbon materials for this emerging segment of the energy market. 

Carbon comes in many forms and surfaces areas. Graphite can have surface area below 1 m2/g, while high surface area carbon blacks approach 2000 m2/g. If Pt adsorbs onto carbon at the same surface density, the Pt loading (Pt, wt%) will then be a function of the carbon surface area. Assuming that CPA can be adsorbed onto carbon at 1.6 mmol/m2, and PTA at 0.84 mmol/m2 at the respective SEA conditions, plot Pt (wt%) vs. surface area of carbon. 

Fig. 15.15 Cinnamyl alcohol selectivity as a function of conversion in the selective hydrogenation of cinnamaldehyde over differently supported Ru catalysts. Reactions conditions as listed in Tab. 15.4. Data compiled from literature [120,122,123,126], HSAG high-surface area graphite AC activated carbon.

Titanium carbide has also been widely studied. Vinod and Frost prepared relatively high surface area forms of TiC (25-125 m g i) and showed lower corrosion currents at 1.0 V in 100% H3PO4 at 200°C than graphitized XC72. ° The oxygen reduction specific activity of Pt/TiC was superior to that of Pt/C, although this may have been influenced by the larger Pt particles deposited onto the TiC. 

The main difference between carbon nanotubes and high surface area graphite is the curvature of the graphene sheets and the cavity inside the tube. In microporous solids with capillaries which have a width not exceeding a few molecular diameters, the potential fields from opposite walls will overlap so that the attractive force which acts upon adsorbate molecules will be increased in comparison with that on a flat carbon surface [16]. This phenomenon is the main motivation for the investigation of the interaction of hydrogen with carbon nanotubes (Figure 5.14). 

Figure 5.17 Reversible amount of hydrogen (electrochemical measurement at 298 K) versus the BET surface area (circles) of a few carbon nanotube samples including two measurements on high surface area graphite (HSAC) samples...

High surface area graphite (Johnson Matthey, CH10213) with a BET area of 312 m g was activated by partial combustion in flowing air at 773 K for 5 hours. Under these conditions 25 wt% of the graphite was burned off. Subsequently the... 

The preparation of nickel oxide deposits with high surface area on steel, nickel, copper, graphite or titanium electrodes partly for anodic oxidation of organic compounds and the preparation of pressed nickel oxide powder electrodes mainly for application in storage batteries is described. The performance of nickel oxide anodes for batteries is improved by addition of cobaltflljhydroxide... 

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