Sangsun Park

Preparation of Pt Catalysts Supported on ACF with CNF via Catalytic Growth

Carbon supported electrocatalysts are commonly used as electrode materials for polymer electrolyte membrane fuel cells(PEMFCs). These kinds of electrocatalysts provide large surface area and sufficient electrical conductivity. The support of typical PEM fuel cell catalysts has been a traditional conductive type of carbon black. However, even though the carbon particles conduct electrons, there is still significant portion of Pt that is isolated from the external circuit and the PEM, resulting in a low Pt utilization. Herein, new types of carbon materials to effectively utilize the Pt catalyst are being evaluated. Carbon nanofiber/activated carbon fiber (CNF/ACF) composite with multifunctional surfaces were prepared through catalytic growth of CNFs on ACFs. Nickel nitrate was used as a precursor of the catalyst to synthesize carbon nanofibers(CNFs). CNFs were synthesized by pyrolysising CH4 using catalysts dispersed in acetone and ACF(activated carbon fiber). The as-prepared samples were characterized with transmission electron microscopy(TEM), scanning electron microscopy(SEM). In TEM image, carbon nanofibers were synthesized on the ACF to form a three-dimensional network. Pt/CNF/ACF was employed as a catalyst for PEMFC. As the ratio of prepared catalyst to commercial catalyst was changed from 0 to 50%, the performance of the mixture of 30 wt% of Pt/CNF/ACF and 70wt% of Pt/C commercial catalyst showed better perfromance than that of 100% commercial catalyst. The unique structure of CNF can supply the significant site for the stabilization of Pt particles. CNF/ACF is expected to be promising support to improve the performance in PEMFC.

Multicomponent Proton Conducting Ceramics of SiO2–TiO2–ZrO2–P2O5–Bi2O3 for an Intermediate Temperature Fuel Cell

The multicomponent proton conducting ceramics SiO 2 ―TiO 2 ―ZrO 2 ―P 2 O 5 (STZP) and SiO 2 ―TiO 2 ―ZrO 2 ―P 2 O 5 ―Bi 2 O 3 with three different compositions (STZPBi3, STZPBi10, and STZPBi15) were synthesized via a wet chemical route. These prepared materials showed good thermal stability up to around 900°C by TG/DTA analyses. Introduction of optimum quantity of bismuth as a sintering aid into the samples contributed to enhance the densification of microstructure, which is essential for the utilization of proton conducting ceramics in fuel cells operated at elevated temperature. The proton conductivity of STZP was 3.6×10 ―5 Slcm at 80°C and that of STZPBi10 was 4.6×10 ―3 Slcm at 180°C. The fuel cell performances using STZP and STZPBi10 were implemented at 80°C and up to 230°C, respectively. The maximum power density was 0.03 mW/cm 2 at 80°C for the STZP sample and 2.5 mW/cm 2 at 150°C for the STZPBi10 sample under wet hydrogen and dry oxygen. The reduction of CO poisoning on platinum catalyst was demonstrated in fuel cell operating at temperatures of 180 ° C, 200 ° C, and I 230°C.

A Study on the Preparation and Application of Au/TiO 2 Nanofiber from AAO Template

In this study, highly ordered AAO (Anodic Aluminum Oxide) with nanopores was prepared by commercial grade Al substrate containing 3.5 wt.% impurities through two step anodizing method. Nanopores of prepared AAO arrays were used as templates for preparing nanofiber. was deposited by using DP (deposition-precipitation) method into AAO pores to grow nanofiber. Au particles were loaded on this nanofiber which was grown vertically. Prepared 2 wt.% nanofiber was characterized by XRD, SEM and Raman. The crystal structure was analyzed by the XRD. SEM was used to observe pore size and pore wall thickness. Photocatalytic activity of co-oxidation was compared with and nanofiber on AAO arrays.

PEMFC Operation Connected with Methanol Reformer System

The studies on integrated operation of fuel cell with fuel processor are very essential prior to its commercialization. In this study, Polymer Electrolyte Membrane Fuel Cell (PEMFC) was operated with a fuel processor, which is mainly composed of two parts, methanol steam reforming reaction and preferential oxidation (PROX). In fuel processor, ICI 33-5 (CuO 50%, ZnO 33%, 8%, BET surface area: ) catalyst and CuO- catalyst were used for methanol steam reforming, preferential oxidation (PROX) respectively. PEMFC was operated by hydrogen fuel generated from fuel processor. The resulting gas from PROX reactor is used to operate PEMFC equipped with our prepared anode and cathode catalyst. PtRu/C catalyst gives more tolerance to CO.