Carbon-hydrogen oxidation reactions

Stohr, B., Boehm, H.P., and Schlogl, R. Enhancement of the catalytic activity of activated carbons in oxidation reactions by thermal treatment with ammonia or hydrogen cyanide and observation of a superoxide species as a possible intermediate. Carbon 29, 1991 707-720. 

Selection of the working electrode substrates, such as glassy carbon or pyrolytic graphite. These substrates have insignificant catalytic activity towards fuel cell reactions (e.g., ORR, hydrogen oxidation reaction [HOR], and methanol oxidation), so they will not interfere with the catalytic activity of the targeted catalyst. 

The precise mechanism of interaction between SO2 and these nitrogen groups remains an open issue. In addition, it has been shown that the enhanced catalytic activity of ammonia-treated carbons is not lost upon subsequent heating at high temperatures under nitrogen or hydrogen, a treatment that removes most of the nitrogen. The catalytic activity of these carbons in oxidation reactions was explained in terms of the formation of superoxides,... 

Different catalysts are used for AFCs. For the hydrogen oxidation reaction, carbon-supported platinum and platinum-palladium catalysts (e.g., noble metal catalysts) are suitable. However, one of the advantages of the AFC compared with acid electrolyte fuel cells, including the phosphoric acid fuel cell (PAFC) and the... 

The catalyst layer consists of the platinum catalyst, carbon as porous support material and an ionomer coating that is usually a polysulfonic acid, forming a three-phase boundary between the electrically conductive material, the ionic conductive material, and the gas phase. The hydrogen oxidation reaction (HOR)... 

Uchida H, Izumi K, Aoki K, Watanabe M (2009) Temperature-dependence of hydrogen oxidation reaction rates and CO-tolerance at carbon-supported... 

The kinetics of the preferential oxidation reaction of carbon monoxide (PrOx), for the hydrogen oxidation reaction (H2OX) and for the reverse water-gas shift reaction (RWGS) were provided, which had been determined in the relevant parameter space [398] ... 

Babic BM, Vracar Lj M, Radmilovic V, Krstajic NV. Carbon cryogel as support of platinum nano-sized electrocatalyst for the hydrogen oxidation reaction. Electrochim Acta2006 51(18) 3820-6. 

The adsorption, desorption, and electro-oxidation reactions of hydrogen and carbon monoxide are discussed. The hydrogen oxidation reaction requires the dissociation of the hydrogen molecule onto bare platinum sites. The CO molecules will also adsorb on the Ft sites, and require oxidation at higher electrode potentials in the range of 0.6 to 0.9 V for removal. Since this potential does not readily occur on the anode, the hydrogen oxidation occurs on a reduced number of Ff sites, resulting in increased anode overpotential. 

So far, the Pt-Ru alloy has shown the most promising performance for the oxidation of methanol and hydrogen oxidation reaction in the presence of CO. Carbon black has been used as support for the metal nanoparticles, particularly Vulcan XC-72 (Cabot), which has a surface area of 240 m g . Methanol oxidation starts at lower potential values for all the Pt-Ru/C catalysts than for Pt/C anodes. Comparison of electrodes prepared with Pt and Pt-Ru as the electrocatalyst supported on nanotubes and those prepared with the most usual support, Vulcan XC-72 showed that multi-wall carbon nanotubes produce catalysts (Pt-Ru/MWNT) with better performance than on other supports, particularly with respect to those prepared with the traditional Vulcan XC-72 carbon powder [18],... 

Basically, an MCFC consists of fwo porous elecfrodes, separafed by a molten electrolyte held in place by a matrix as seen in Figure 9.13. In the three-phase region on the anode side, hydrogen oxidation reaction occurs and hydrogen combines with carbonate ions, producing water and carbon dioxide while... 

Fig. 11 A proton exchange membrane fuel cell experiencing Hj/air front start/stop, showing the major electrochemical reactions considered during start/stop operations. ORR Oxygen reduction reaction, COR Carbon oxidation reaction, OER Oxygen evolution reaction, and HOR Hydrogen oxidation reaction...

Fig. 4 Principle of the reverse current region. For details see the text. COR carbon oxidation reaction, OER oxygen evolution reaction, ORR oxygen reduction reaction, HOR hydrogen oxidation reaction, GDL gas-diffusion layer, CL catalyst layer...

The electrodes used in PAFCs are generally Pt-based catalysts dispersed on a carbon-based support. For the cathode, a relatively high loading of Pt is necessary for the promotion of the O2 reduction reaction. The hydrogen oxidation reaction at the anode occurs readily over a Pt/C catalyst. 

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