Study of BH4- electrooxidation on catalysts composed by gold and platinum on alkaline media.

• Grant number: 09/18332-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2010
• End date: December 31, 2010
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
• Principal Investigator: Fabio Henrique Barros de Lima
• Grantee: Aniélli Martini Pasqualeti
• Host Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

The direct borohydride fuel cells (DBFC) are high power density electrochemical conversor devices. The total oxidation of the borohydride, BH4-, that takes place in the anode, involves the transfer of 8 electrons per ion. However, this reaction has a complex mechanism, with slow kinetics. In electrocatalysts composed by gold or platinum, the total oxidation reaction competes with parallel reactions with lower number os exchanged electrons, or with the BH4- hydrolysis, producing H2. Therefore, it is necessary to futher advance in the understanding of the mechanism of borohydride oxidation reaction, and to develop electrocatalysts that promote the direct BH4- oxidation, involving 8 electrons per ion.In this work, the electrocatalytic activity for the borohydrid oxidation will be studied on polycrystalline "bulk" Au and Pt, and nanostructured. Also, it will be investigated the influence of the combination of Au and Pt atoms, in different atomic compostions, on the reaction mechanism. Finally, it will be studied the electrocatalytic activity in function of the Au and Pt altered electronic structure in bimetallic Au-Ag and Pt-Pd nanoparticles. The electrocatalytic activity will be studied by steady state polarization curves using rotating disc electrodes. The borohydride hydrolysis, with the production of H2, will be monitored in function of the electrode potential by on-line differential electrochemical mass spectrometry. The final objective is to further advance in the elucidation of the reaction mechanism, and in the correlation of the borohydrid oxidation kinetics, and hydrolysis reaction, with the electronic and structural features of the electrocatalysts.