Effects of Calcination Temperature on Characteristics of Electrospun TiO₂Catalyst Supports for PEMFCs

Abstract

>> Polymer Electrolyte Membrane Fuel Cell (PEMFC) is a power generation system to convert chemical energy of fuels and oxidants to electricity directly by electrochemical reactions. As a catalyst support for PEMFCs, carbon black has been generally used due to its large surface area and high electrical conductivity. However, under certain circumstances (start up/shut down, fuel starvation, ice formation etc.), carbon supports are subjected to serve corrosion in the presence of water. Therefore, it would be desirable to switch carbon supports to corrosion-resistive support materials such as metal oxide. TiO2 has been attractive as a support with its stability in fuel cell operation atmosphere, low cost, commercial availability, and the ease to control size and structure. However, low electrical conductivity of TiO2 still inhibits its application to catalyst support for PEMFCs. In this paper, to explore feasibility of TiO2 as a catalyst support for PEMFCs, TiO2 nanofibers were synthesized by electrospinning and calcinated at 600, 700, 800 and 900℃. Effects of calcination temperature on crystal structure and electrical conductivity of electrospun TiO2 nanofibers were examined. Electrical conductivity of TiO2 nanofibers increased significantly with increasing calcination temperature from 600℃ to 700℃ and then increased gradually with increasing the calcination temperature from 700℃ to 900℃. It was revealed that the remarkable increase in electrical conductivity could be attributed to phase transition of TiO2 nanofibers from anatase to rutile at the temperature range from 600℃ to 700℃.