Application of phosphoric acid and phytic acid-doped bacterial cellulose as novel proton-conducting membranes to PEMFC

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• 作者：Gaopeng Jiang^a ; ^b ; Jinli Qiao^b ; ^{qiaojl@dhu.edu.cn} ; ^{qiaojinli@hotmail.com} ; Feng Hong^a ; ^c ; ^{fhong@dhu.edu.cn}
• 关键词：Bacterial cellulose ; Phosphoric acid ; Phytic acid ; Proton-conducting membrane ; PEMFC
• 刊名：International Journal of Hydrogen Energy
• 出版年：2012
• 期刊代码：42_03603199
• 类别：ch
• 出版时间：June, 2012
• 卷：37
• 期：11
• 页码：9182-9192
• 文件大小：1077 K

摘要

Novel proton-conducting polymer electrolyte membranes have been prepared from bacterial cellulose by incorporation of phosphoric acid (H₃PO₄/BC) and phytic acid (PA/BC). H₃PO₄ and PA were doped by immersing the BC membranes directly in the aqueous solution of H₃PO₄ and PA, respectively. Characterizations by FTIR, TG, TS and AC conductivity measurements were carried out on the membrane electrolytes consisting of different H₃PO₄ or PA doping level. The ionic conductivity showed a sensitive variation with the concentration of the acid in the doping solution through the changes in the contents of acid and water in the membranes. Maximum conductivities up to 0.08聽S聽cm^鈭? at 20聽掳C and 0.11聽S聽cm^鈭? at 80聽掳C were obtained for BC membranes doped from H₃PO₄ concentration of 6.0聽mol聽L^鈭? and, 0.05聽S聽cm^鈭? at 20聽掳C and 0.09聽S聽cm ^鈭? at 60聽掳C were obtained for BC membranes doped from PA concentration of 1.6聽mol聽L^鈭?. These types of proton-conducting membranes share not only the good mechanical properties but also the thermal stability. The temperature dependences of the conductivity follows the Arrhenius relationship at a temperature range from 20 to 80聽掳C and, the apparent activation energies (E_a) for proton conduction were found to be 4.02聽kJ聽mol^鈭? for H₃PO₄/BC membrane and 11.29聽kJ聽mol^鈭? for PA/BC membrane, respectively. In particular, the membrane electrode assembly fabricated with H₃PO₄/BC and PA/BC membranes reached the initial power densities of 17.9聽mW聽cm^鈭? and 23.0聽mW聽cm^鈭?, which are much higher than those reported in literature in a real H₂/O₂ fuel cell at 25聽掳C.