Oxygen based cathodes

The initial polarization behavior for the oxygen reduction on LSM-based cathodes is characterized by a well-known activation phenomenon, as shown in... 

Encouraging laboratory experiments since 1994 with oxygen-depolarised cathodes (ODC) in chlor-alkali as well as hydrochloric acid electrolysis motivated the development of this technique up to the industrial scale. Based on the predictions of the theory, the reduction of cell voltage could be expected up to 1 V (Fig. 4.1) for both applications. Early on, the proper choice and improvement of ODC, deriving mainly from the DeNora group, led to results with voltages as predicted in short tests as well as in endurance tests conducted over dozens of months at the Bayer endurance test facilities. 

Fig. 9.3 An unpurified MDI-type HCI feed test of a laboratory cell (1 dm2) with a rhodium-based oxygen-depolarised cathode.

Fig. 9.5 Cell voltage results of an HCIaq pilot electrolyser (four cells, 0.88m2 each) with rhodium-based oxygen-depolarised cathodes.

A fascinating option is offered by carbon-based oxygen-consuming cathodes, which can reduce oxygen into hydrogen peroxide (e.g. [50]). Thus, an oxidizing agent is produced at the cathode In combination... 

For polymer electrolyte membrane fuel cell (PEMFC) applications, platinum and platinum-based alloy materials have been the most extensively investigated as catalysts for the electrocatalytic reduction of oxygen. A number of factors can influence the performance of Pt-based cathodic electrocatalysts in fuel cell applications, including (i) the method of Pt/C electrocatalyst preparation, (ii) R particle size, (iii) activation process, (iv) wetting of electrode structure, (v) PTFE content in the electrode, and the (vi) surface properties of the carbon support, among others. ... 

It can be understood that the temperature of the exothermic peak with oxygen evolution increased from 200°C of LiNiO to 310°C of LiNi gCo j Al due to the decrease in the nickel content and the aluminum doping. The thermal stability of this compound has been considerably improved. The oxygen evolution was not observed below 300°C. On the whole, the thermal stabihty of this is more excellent than that of LiCoO and comparable to that of spinel LiMn O. hi addition, the SEM image of this material is shown in Fig. 2.23. It would be possible to control the powder characteristics the same as the co-precipitation method. It is clear from Table 2.5 that this material has a larger capacity than that of the cobalt-based cathode. This cathode delivers more than 180 mAh/g for 4.3 V charge, as shown in Fig. 2.24. 

N. Funiya, H. Syojaku, H. Aikawa, and O. Ichinose, Ag Based Oxygen Cathodes for Chlor-Alkali Membrane Cells. In J.W. Van Zee, P.C. Foller, T.F. Fuller, and F. Hine (eds.). Advances in Mathematical Modelling and Simulation of Electrochemical Processes and Oxygen Depolarized Cathodes and Activated Cathodes for Chlor-Alkali and Chlorate Processes, Proc. vol. 98-10, The Electrochemical Society, Pennington, NJ (1998), p. 243. 

An electrolytic technology for the preparation of ozone was based on glassy carbon as the anode material in concentrated fluoroboric acid (HBF ) [22-24]. The cells also employed a Pt-catalyzed, oxygen reduction cathode (gas diffusion electrode (GDE)) to lower the cell voltage (and hence the energy consumption) and to avoid the need to handle H2 off-gas from the cathode. It was necessary to operate with cooling, and the preferred temperature was 268 K. 

Chlorine and Caustic Technology, Using Oxygen Depolarized Cathode, Fig. 2 Scheme of one pore in a gas diffusion electrode (GDE, based on [7])... 

Pinnow S, Chavan N, Turek T (2011) Thin-film flooded agglomerate model for silver-based oxygen depolarized cathodes. J Appl Electrochem 41 1053-1064. doi 10.1007/sl0800-011-0311-2... 

The above reaction was promoted when using (La,Sr)Mn03-based cathode because the oxygen reduction was only active at the gas/(La,Sr) Mn03/electrolyte interfaces (triple phase boundaries) [14]. Other cathode, such as (La,Sr) (Co,Fe)03, shows relatively high chemical reactivity with Cr vapor to form SrCr04 on the surface. The difference of reaction products and electrochemical degradation was determined by the reactivity and electrochemical activities. 

Platinum-Based Cathode Catalysts for Polymer Electrolyte Fuel Cells, Fig. 2 DFT activities as a function of the oxygen binding energy derived by density functional theory (DFT) calculations. The volcano is in good agreement with experiment, showing that Pt is the best catalysts for oxygen reduction (Ref. [16])... 

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