M. Oropeza Guzmán, Y. Gochi Ponce, G. Moreno
Tecnologico Nacional de Mexico-Instituto Tecnologico de Tijuana,
Keywords: electrophoretic deposition, carbon nanotubes, nanoelectrocatalysts
Summary:A new challenge of nanoelectrocatalytic materials is to find a convenient method to support them on surfaces serving as fuel cell electrodes. Traditionally, researchers have tried to prepare colloidal inks containing the nanoelectrocatalyst previously synthesized to deposit thin films over fuel cells current collectors. Also imprinted electrodes have been tried. A large number of papers report ink dropping methods to form thin layers on electrode surfaces (~0.25cm2), and in few cases spin-coating or electrospining methods. However, results are still poor since after two or three electrochemical tests, the thin layer is peeled off because it’s low adherence. Concerning the imprinted electrodes they are characterized by larger thickness straightly related with ohmic drops when electrode areas are increased. In this work authors present an alternative to form thin layers of nanoelectrocatalytic materials as raw carbon nanotubes and modified carbon nanotubes (CNT)expecting to improve conventional methanol fuel cells open circuit potential. Electrophoretic Deposition (EPD) is a well known method to prepare advanced coatings as well as functional graded materials. With this method followed by thermal treatments, better adherence of nanoelectrocatalytic materials was achieved, improving the electrode life time and the possibility to fabricate larger electrodes (10 cm2), at least to be able to test the nanoelectrocatalysts in real fuel cells. EPD was performed controlling current density, deposition time and temperature for two different colloidal concentrations of raw CNTs and CNTs modified with W-Pt-S nanoparticles. Results are compared and evaluated to determine the life time improvement as well as the electrocatalytic properties of fuel cells electrodes at medium scale. EPD is a cheaper method requiring minimal operating and maintenance costs, with possibility to re-concentrate the colloidal fluid or ink just adding more nanoelectrocatalysts to the EPD cell.