Colloidal methods Bonnemann method

Although the Bonnemann method is very interesting by allowing to vary and to control easily the composition and the nanostructure of the catalyst and is adapted to the preparation of real fuel cell electrodes, it displays also some limitations. For example, bismuth-containing colloids could not be prepared with the Bonnemann method, and even in presence of platinum salts. Moreover, the presence of bismuth hinders the reduction of platinum salts [59], However, platinum-bismuth is a good catalyst for ethylene glycol electro-oxidation in alkaline medium [59-62], Moreover, colloid of tin alone could not be obtained, and the reaction was only possible by coreduction in the presence of a platinum salt. Then, other colloidal methods should be developed keeping in mind the necessity of a similar flexibility as that of the Bonnemann method. 

One step methods. PtRuMo/C catalysts obtained by the impregnation manner revealed that the addition of a relatively small amount of Mo results in an electrocatalyst with a higher activity in CO or methanol electrooxidation than with the PtRu/C system. Moreover, Benker et al studied the effect of molybdenum precursor, and the physico-chemical characterization indicated that only traces of molybdenum were present in the samples when Mo (CO) 6 was used for the synthesis, while ammonium molybdate was an appropriate precursor for the synthesis of PtRuMo/C catalysts. On the other hand, a colloidal method developed by Bonnemann et alP was used to prepare carbon supported PtRuMo nanoparticles and established that this method provided a better tool for synthesizing PtRuMo (1 1 1) nanoparticles deposited on a carbon substrate, being more... 

Following up on half-cell experiments, it is of great interest to characterize the products obtained in direct ethanol fuel cells. Rousseau et al. investigated direct ethanol fuel cells employing Pt, PtSn (9 1 at. ratio), and PtSnRu (8.6 1 0.4) anode electrocatalysts supported on Vulcan XC72 prepared by the Bonnemann colloidal method (3 mg cm Pt content) [183]. 

Bonnemann, H., Brij oux, W., and Brinkmann, R., Method for modifying the dispersion characteristics of metal-organic-prestabilized or pre-treated nanometal colloids, WO 99/59713, (to Studiengesellschaft Kohle), November 25,1999. 

What are the advantages of Bonnemann s method of colloidal nanoparticle synthesis ... 

The radiation method was described by Rogninski and Schalnikoff for the first time and is based on condensation of the metal atoms after collision [154]. Reetz et al. prepared nanoparticles via electrochemical synthesis [155]. Salt reduction was developed by Bonnemann to obtain mono- and bi-metallic nanoparticles in solution [156]. Salt reduction is the most widely practised method for the synthesis of colloidal metal suspensions. Faraday synthesised gold particles by the reduction of HAuCb [157]. 

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