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Title:	Assembly of acid doped polybenzimidazole membrane with modified multi-walled carbon nanotube supported platinum electrode for high- temperature pem fuel cell
Authors:	Md Ahsanul Haque (P77790)
Supervisor:	Abu Bakar Sulong, Assoc. Prof. Ir Dr.
Keywords:	Proton exchange membrane fuel cells Fuel cells Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	24-Oct-2018
Description:	Proton exchange membrane fuel cell (PEMFC) is one of the prominent green energy conversion devices in the field of fuel cell. The stability of electrocatalyst is one of the major limitations for the commercialization of high temperature PEMFC. This limitation can be solved by developing the material compatibility between the catalyst and catalyst support materials. In this research, electrocatalysts were synthesized from polymer coated multi walled carbon nanotube (MWCNT) supporting materials with platinum (Pt) catalyst by polyol method while hexachloroplatinic acid (H2PtCl6) used as catalyst precursor. The MWCNT was modified using polybenzimidazole (PBI), sulfonated tetrafluoroethylene (Nafion), and polytetrafluoroethylene (PTFE) polymers coated by functionalization and solution processing methods. Subsequently, Pt was deposited onto the MWCNT, MWCNT/PBI, MWCNT/Nafion and MWCNT/PTFE supporting materials to synthesize the MWCNT/Pt, MWCNT/PBI/Pt, MWCNT/Nafion/Pt and MWCNT/PTFE/Pt electrocatalysts. In addition, polybenzimidazole (PBI) electrolyte membranes were optimized the acid doping level (ADL) using Taguchi method and characterized by proton conductivity, oxidative stability, tensile strength and thermogravimetric analysis. Subsequently, membrane electrode assembly (MEA) was fabricated by hot pressing method while acid doped PBI membrane sandwiched between two electrodes. The maximum proton conductivity recorded at 6.30 mS/cm of acid doped PBI copolymer-1 membrane. This occurred under optimized conditions of doping temperature 130 °C, doping time 6 h, and 160 °C operating temperature, which were confirmed by analysis of the main effect and contour plot of those parameters. Besides that, the maximum weight loss of PBI copolymer-1 was observed by 4.5 % that imparts the excellent chemical stability. Meanwhile, the high thermal resistance and mechanical strength proved by the tensile test and TGA analysis. The synthesized catalyst supporting materials were characterized by cyclic voltammetry (CV), chronoamperometric (CA), X-ray diffraction (XRD), BET surface area techniques and the morphological studied. The BET surface area was significantly increased due to the polymer ionomer incorporated onto the MWCNT surfaces, which was measured at 225.13 m2g-1 of MWCNT/PBI, 319.02 m2g-1 of MWCNT/Nafion, 206.95 m2g-1 of MWCNT/PTFE and 178.04 m2g-1 of pristine MWCNT. The polymer coated MWCNT based Pt electrocatalysts were exhibited high electrochemical stability that endorsed by chronoamperometric analysis whereas, the retention rate of 43.85 % and 3.26 % were obtained by MWCNT/PBI/Pt and MWCNT/Pt, respectively. The electrons transfer number (n) was calculated from the K-L plot at 3.83, 3.99, 3.84, and 4.01 for MWCNT/Pt, MWCNT/PBI/Pt, MWCNT/Nafion/Pt and MWCNT/PTFE/Pt electrocatalysts, respectively. This finding suggests that the ORR reaction mechanism of electrocatalysts are dominated by four electrons transfer reaction pathways. Moreover, the fabricated MEAs were successfully demonstrated in single cell and the maximum power density obtained at 112.10 mW/cm2 under 150 °C operating temperature. In conclusion, the synthesized electrocatalysts and catalyst supporting materials have enhanced the electrochemical stability which indicates the fulfillment of the main objective of this research.,Ph.D.
Pages:	158
Call Number:	TK2933.P76H3457 2018 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Fuel Cell Institute / Institut Sel Fuel

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