Novel Carbon Materials as Supports for Fuel Cell Electrocatalysts

3 Novel Carbon Materials as Supports for Fuel Cell Electrocatalysts 

Recently, utilization of CNFs and CNTs in the CLs of PEMFCs and DMFCs has become an active research area. Numerous studies have focused on the stabilization of Pt and PtRu particles on the surface of CNTs and CNFs (see the review articles [153 and 230] and references therein). Adhesion of Pt to the basal plane of graphite is weak thus various approaches have been proposed to activate CNTs, including oxidation, grafting with various functional groups [153], and wrapping with a polymer [231], in order to stabilize highly dispersed Pt on their surfaces. Pt and Pt-Ru particles supported on CNTs and CNFs were tested in the oxygen reduction reaction and in the methanol oxidation reaction. 

In numerous publications, authors claim higher activity of CNF- and CNT-supported catalysts for fuel cell apphcations, which they attribute to (1) higher electron conductivity, (2) higher particle dispersion, (3) facilitated mass transport, and (4) improved water management. Unfortunately, the conclusions on the origin of the catalytic activity enhancement often lack experimental 

Methanol oxidation on CNF- and CNT-supported Pt-Ru particles in liquid electrolytes has been studied using cyclic voltammetry, chronoamperometry [13,231-237], and electrochemical impedance spectroscopy [236]. Rotating disk electrode and linear potential sweep voltammetry in liquid electrolytes were used to study the oxygen reduction reaction on Pt supported on CNTs and CNFs (see, 

CARBON MATERIALS AS SUPPORTS FOR FUEL CELL ELECTROCATALYSTS 

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Carbon supports strongly affect fuel cell performance. They may influence the intrinsic catalytic activity and catalyst utilization, but also affect mass transport and ohmic losses. This makes analyses of the role of carbon materials rather complicated. Although numerous studies have been devoted to the carbon support improvement, only a few have attempted to establish relationships between the substructural characteristics of carbon support materials and cell performance. The influence of carbon supports on the intrinsic catalytic activity is the subject of Section 12.6.1. In Section 12.6.2 we consider the influence of support on macrokinetic parameters such as the catalyst utilization, mass transport, and ohmic losses. In Section 12.6.3 we review briefly recent data obtained upon utilization of novel carbon materials as supports for fuel cell electrocatalysts. 

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