| Summary: | 碩士 === 國立雲林科技大學 === 電子工程系 === 105 === In the proton exchange membrane fuel cell (PEMFC), oxygen, hydrogen ions and electrons reduced at cathodic catalyst layer to produce water, and then through the gas diffusion electrode (GDE) to remove water out of the fuel cell. Therefore, water management in the gas diffusion layer is an important issue. The purpose of this study was to synthesize graphene and zinc oxide nanorods on porous metal nickel foam by chemical vapor deposition and hydrothermal method, respectively. The preparation of converted hyfdrophobic/hydrophilic ZnO NRs/graphene/NiF composite gas diffusion electrode applied on the PEMFC.
The first part of this study was to investigate the effects of the thickness of ZnO seed layer and precursor concentration of hydrothermal method. The morphology of nanorod surface would effect hydrophobicity. The grain size of seed layer increased from 23.23 nm to 33.17 nm with the increase of the sputtering time and annealing. It existed a clear (002) crystal orientation. The maximum absorbance wavelength of ZnO nanorods was decreased from 371 nm to 364 nm with the increase of precursor concentration (12.5 mM→25 mM) with UV/VIS spectrometer. With the image of SEM, the surface coverage increased from 37.77% to 65.41% when the concentration of precursor was increased from 12.5 mM to 25 mM with imageJ image analysis software. The contact angles were 129.63 ° after treatment with stearic acid 109.31°. The surface contact angle of the ZnO nanorods was measured per 10 minutes by UV light irradiation. The second part of the preparation of graphene/ZnO NRs composite material, in the UV light wavelength has a significant increase in the absorbance, and the contact angle increased to 145.57 °.With UV light irradiation was converted to hydrophilic between 20 to 30 minutes, faster than the original 60 to 70 minutes of conversion time. Finally, the graphene was synthesized by direct chemical vapor deposition (CVD) with nickel foam, and then the ZnO NRs/ graphene/NiF composite gas diffusion electrode was prepared by hydrothermal synthesis of ZnO NRs. The contact angle of the pureNiF is about 127.1°, the contact angle of the graphene/NiF is about 137.77 °, and the ZnO NRs/graphene/NiF was exposed with UV light, caused water droplets to permeate the structure, and contribute to the gas diffusion electrode water removed mechanism.
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