应用电化学循环伏安法(CV)和现场红外光谱(FTIR),研究了酸性溶液中钯催化甲醇、乙二醇电氧化的过程.结果表明:在酸性和中性介质中,甲醇和乙二醇在多晶Pd电极上氧化须在1.5V以上才能发生.随着溶液pH值的降低,过电位减小且峰电流密度上升.溶液的pH值以及电极表面形成的吸附含氧物种对Pd电催化氧化醇有显著的影响.现场红外光谱电化学测试显示,在高电位和强酸性介质中,乙二醇在Pd电极上的氧化产物主要是CO2和少量的乙二酸.在酸性和中性介质中,无论在低电位或高电位,甲醇和乙二醇在Pd上氧化的主要产物是CO2,没有发现CO的存在,说明该氧化过程CO2是经过非毒化的路径产生的.
The methanol and ethylene glycol electrooxidation on palladium electrode in acidic solution has been investigated by cyclic voltammetry and in situ Fourier transform infrared spectroelectrochemistry. It shows that the oxidation of methanol and ethylene glycol at Pd electrode cannot proceed until over 1. 5 V in acidic and neutral media. The overpotential decreases and the peak current density increases with the reduction in pH values. The formation of the oxygen-containing species significantly affects the alcohol oxidation on Pd electrode. The in situ FTIR spectroscopic measurements show that the oxidation products of ethylene glycol on Pd electrode are CO2 and oxalic acid at high potentials and concentrated acid solution. However,the dominant product is CO2 for the oxidation of both methanol and ethylene glycol in acidic and neutral solutions,indicating that the pathway of methanol or ethylene glycol oxidation is a non-poisoning process.
[1]Wang Mei-li(黄美丽),Sang Lin(桑林),Huang Chen-de(黄成德).Electro-oxidation of methanol on PdNiO/C catalyst in alkaline medium[J].Electrochemistry(电化学),2007,13(4):377-381.
[2]Wen Gang-yao(文纲要),Zhang Ying(张颖),Yang Zheng-long(杨正龙),et al.Investigation of methanol anode electrooxidation catalysts[J].Electrochemistry(电化学),1998,4(1):73-78.
[3]Gasteiger H,Markovic N,Ross P.New catalyst with the property of CO tolerance[J].Phys Chem,1995,(99):8290-8296.
[4]Li Lan-lan(李兰兰),Wei Zi-dong(魏子栋),Yan Can(严灿),et al.Methanol oxidation on a Pt electrode modified by underpotential deposition of Ru[J].Acta Physico-Chimica Sinica(物理化学学报),2007,23(5):723-727.
[5]Grgur B N,Markovic N M,Ross P N J.Preparation of a CO tolerant anode catalyst for fuel cells[J].Phys Chem,1998,102:2494-2499.
[6]Xie Fang-yan(谢方艳).Studies of facilitated mass t-ransport in direct alcohol fuel cell[D].Guangzhou:Sun Yat-sen University,2005.14-15.
[7]Bianchini C,Shen P K.Palladium-based electrocatalysts for alcohol oxidation in half cells and in direct alcohol fuel cells[J].Chem Rev,2009,109:4183-4206.
[8]Yan Zhi-yuan(严志远),Xu Chang-wei(徐常威),ShenPei-kang(沈培康).Study of the electrooxidation of glycerol on oxide and Pd/C composite catalysts[J].E-lectrochemistry(电化学),2006,12(4):408-411.
[9]Shen P K,Xu C W.Alcohol oxidation on nanocrystaline oxide Pd/C promoted electrocatalysts[J].Electrochem Commun,2006,8:184.
[10]Hu F P,Cui G F,Wei Z D.Improved kinetics of etha-nol oxidation on Pd catalysts supported on tungsten car-bides/carbon nanotubes[J].Electrochimi Acta,2008,53:8341-8345.
[11]Xu C W,Chen L Q,Shen P K,et al.Methanol and eth-anol electrooxidation on Pt and Pd supported on carbon microspheres in a alkaline media[J].Electrochem Commun,2007,9:997-1001.
[12]Cui G F,et al.First-principles considerations on cata-lytic activity of Pd toward ethanol oxidation[J].J Phys Chem C,2009:15639-15642.
[13]Chen Ai-cheng(陈爱成),Sun Shi-gang(孙世刚).In Situ FTIR reflection spectroscopic studies of adsorption and oxidation of ethylene glycol on Pt electrode(I)—acidic media[J].Chem J Chin Univ(高等学校化学学报),1994(15):401-405.
[14]Fang X.An in situ Fourier transform infrared spectro-electrochemical study on ethanol electrooxidation on Pd in alkaline solution[J].J Power Sources,2010,195:1375-1378.
[15]Liang Z X,Zhao T S,Xu J B,et al.,Mechanism study of the ethanol oxidation reaction on palladinum in alka-line media[J].J Electrochimi,2203-2208.
[16]Dong Qing-nian(董庆年).The methods of infrared spectroacopy[M].Beijing:Chemical Industry Press,1979.104-128.
