Electrochemical performance improvement of the catalyst of the methanol
micro-fuel cell using carbon nanotubes
Abstract
Due to low working temperature, high energy density and low pollution,
proton exchange fuel cells have been investigated under different
operating conditions in different applications. Using platinum catalysts
in methanol fuel cells leads to increasing the cost of this kind of fuel
cell which is considered as a barrier to the commercialism of this
technology. For this reason, a lot of efforts have been made to reduce
the loading of the catalyst required on different supports. In this
study, carbon black (CB) and carbon nanotubes (CNT) have been used as
catalyst supports of the fuel cell as well as using the double-metal
combination of platinum-ruthenium (PtRu) as anode electrode catalyst and
platinum (Pt) as cathode electrode catalyst. The performance of these
two types of electro-catalyst in the oxidation reaction of methanol has
been compared based on electrochemical tests. Results showed that the
carbon nanotubes increase the performance of the micro-fuel cell by 37%
at maximum power density, compared to the carbon black.Based on
thee-electrode tests of chronoamperometry and voltammetry, it was found
that the oxidation onset potential of methanol for CNT has been around
20% less than CB, leading to the kinetic improvement of the oxidation
reaction.The current density of methanol oxidation reaction increased up
to 62% in CNT sample compared to CB supported one, therefore the active
electrochemical surface area of the catalyst has been increased up to
90% by using CNT compared to CB which shows the significant rise of the
electrocatalytic activity in CNT supported catalyst.