Carbon Nanotubes as Material Support for Pt-Based Catalysts and their Use in Direct Methanol Fuel Cells

Abstract

In the last decade carbon nanotubes have turned out to be an important industrial material, being produced hundreds of tons each year. The unique structure of carbon nanotubes makes them an alternative material for catalyst support in fuel cells devices due to their unique one-dimensional nanostructure, high surface area, excellent electronic conductivity, and high chemical and mechanical stability. However, raw nanotubes do not have sufficient binding sites for anchoring metals nanoparticles, which frequently lead to poor dispersion and agglomeration of the nanoparticles. Hence, functionalization of carbon nanotubes is generally an essential issue to further applications. The presence of these surface functional groups modifies the chemical and physical properties of the carbon, improving wettability, adsorption, and cation exchange capacity. Furthermore, these groups act as nucleation centers or anchoring sites, limiting the particle growth and improving the dispersion of metallic crystallites and the stability of the supported catalysts. This chapter is devoted to review the available scientific literature, motivated by the enormous world-wide demand of increasing the production of energy from green renewable technologies. In the need of developing new, better-performing catalysts for direct methanol fuel cells applications, the present survey is focused on synthesis of catalytically active metal nanoparticles, such as Pt, and Pt-Me (Me: Ru, Sn, Mo, Os, etc.) decorating the external walls or the interior of the carbon nanotubes and carbon nanotubes/polymer composites.