PtRu/C表面甲醇电催化氧化动力学的非线性谱学分析

doi:10.7503/cjcu20180156

摘要/Abstract

摘要：

应用新一代电化学谱学分析方法——总谐波失真(THD)谱考察了PtRu/C表面甲醇电催化氧化的非线性频响行为, 并通过对比Ru含量不同的催化剂表面甲醇氧化THD谱的实验表征与数值模拟结果, 探讨了其在甲醇电催化氧化机理识别以及电极性能诊断中应用的可行性. THD谱的实验结果表明, 在0.25~1 Hz频率范围内, THD谱强度随Ru含量的降低而增加, 随甲醇浓度损失的降低而降低. 相反的变化趋势使THD相比于电化学阻抗谱(EIS)在这2种失效的诊断中优势更加明显. THD谱的数值模拟结果表明, 在中间产物氧化电势相关性与反应物等温吸附模式不同的机理比较中, 基于Kauranen-Frumkin/Temkin机理的甲醇氧化动力学可以再现不同Ru含量的PtRu/C表面甲醇电催化氧化的线性与非线性频率响应结果.

关键词: 总谐波失真谱, 直接甲醇燃料电池, 非线性频率响应, 钉流失诊断

Abstract:

A new generation of electrochemical spectroscopic analysis——total harmonic distortion(THD) spectrum was used to characterize the nonlinear characteristic frequency response of methanol electrocatalytic oxidation on PtRu/C surface. By comparing the experimental and numerical results of THD spectra of methanol oxidation on Ru catalysts with different contents, this work have qualitatively investigated the feasibility of THD spectrum in methanol electrocatalytic oxidation mechanism identification and electrode performance diagnosis. The experimental results show that in the range of 0.25—1 Hz frequency domain, THD increases with the decrease of Ru content, and decreases with the decrease of methanol concentration. Compared to EIS, THD has advantages over this failure diagnosis due to its opposite tendency of experimental results. The results of numerical simulation of THD spectrum show that according to whether electrode-potential-related step exist in the oxidation of CO_ads and different isothermal adsorption models, the mechanism of methanol oxidation based on Kauranen-Frumkin/Temkin mechanism can reproduce steady state, linear and nonlinear frequency response of methanol electrocatalytic oxidation with different Ru content on PtRu/C surface.

Key words: Total harmonic distortion(THD) spectrum, Direct methanol fuel cell(DMFC), Nonlinear frequency response, Ru loss diagnosis

中图分类号:

O646

TrendMD:

石越, 毛庆, 肖成, 景维云, 张学元. PtRu/C表面甲醇电催化氧化动力学的非线性谱学分析. 高等学校化学学报, 2018, 39(9): 2017.

SHI Yue,MAO Qing,XIAO Cheng,JING Weiyun,ZHANG Xueyuan. Nonlinear Spectroscopy Analysis for Electrocatalytic Oxidation of Methanol on PtRu/C Surface^†. Chem. J. Chinese Universities, 2018, 39(9): 2017.

图/表 7

Table 2 Parameters in the elementary step of the methanol oxidation mechanisms

Parameter	Kaur-Frumk./T	VCS-Frumk./T	Kaur-Langm.	VCS-Langm.
S₁	exp(-β_COg_COθ_CO)	exp(-β_COg_COθ_CO)	1	1
S_-1	exp[(1-β_CO)g_COθ_CO]	exp[(1-β_CO)g_COθ_CO]	1	1
S₂	exp(-β_OHg_OHθ_OH)	exp(-β_OHg_OHθ_OH)	1	1
S_-2	exp(-β_OHg_OHθ_OH)	exp(-β_OHg_OHθ_OH)	1	1
E₃	1	exp(αFη/RT)	1	exp[-(1-α)Fη/RT]
E_-3	1	exp(αFη/RT)	1	exp[-(1-α)Fη/RT]

Fig.1 Steady-state and transient electrochemical response of methanol electrocatalytic oxidation on PtRu/C surface with different Ru content (A) Steady state polarization curves; (B) EIS spectra; (C) THD spectra.

Fig.2 Steady-state and transient electrochemical response of methanol electrocatalytic oxidation on PtRu/C surface with different concentration of methanol (A) Steady state polarization curves; (B) EIS spectra; (C) THD spectra.

Table 3 Fitting results of the kinetic parameters for different methanol electrocatalytic oxidation mechanisms

Model	K₁₀₁	K₁₀₂	K₂₀₁	K₂₀₂	K₃₀₁	K₃₀₂
Kaur-Frumk./T	1.05×10^-1	3.46×10^-6	1.11×10^-6	1.42×10^-6	5.44	1.20×10^-3
Kaur-Langm.	5.87×10^-1	2.06×10^-6	1.11×10^-6	4.52×10^-6	8.18×10^-2	4.36×10^-8
VCS-Frumk./T	9.94×10^-3	2.97×10^-22	2.19×10^-6	9.99×10^-6	2.39×10^-6	9.76×10^-13
VCS-Langm.	6.96×10^-4	3.49×10^-31	9.99×10^-5	2.93×10^-19	1.86×10^-5	9.92×10^-10

Fig.3 EIS simulation results of PtRu/C with different Pt/Ru radios using different methanol electro-oxidation models(A) Kaur-Frumk./T mechanism; (B) Kaur-Langm. mechanism; (C) VCS-Frumk./T mechanism; (D) VCS-Langm. mechanism.

Table 1 Methanol oxidation mechanism on the PtRu/C catalysts

Mechanism	Kaur-Frumk./T	VCS-Frumk./T	Kaur-Langm.	VCS-Langm.
Potential correlation of CO_ads oxidation	Irrelevant	Related	Irrelevant	Related
Isothermal adsorption mode	Frumkin	Frumkin	Langmuir	Langmuir

Fig.4 THD simulation results of PtRu/C with different Pt/Ru radios using different methanol electro-oxidation models (A) Kaur-Frumk./T model; (B) Kaur-Langm. model; (C) VCS-Frumk./T model; (D) VCS-Langm. Model.

参考文献 29

[1]	Liu H., Song C., Zhang L., Zhang J., Wang H., Wilkinson D. P., J. Power Sources, 2006, 155(2), 95—110
[2]	Wasmus S., Küver A., J. Electroanal. Chem., 1999, 461(1/2), 14—31
[3]	Neburchilov V., Martin J., Wang H., Zhang J., J. Power Sources, 2007, 169(2), 221—238
[4]	Zhou W. J., Research on Anode Catalysts for Low-Temperature Direct Alcohol Fuel Cell, Dalian Institute of Chemical Physics, Dalian, 2003
	(周卫江. 低温直接醇类燃料电池阳极催化剂研制, 大连: 大连化学物理研究所, 2003)
[5]	Chen W. M., Studies on the Stability of Electrocatalysts in Direct Methanol Fuel Cells, Dalian Institute of Chemical Physics, Dalian, 2007
	(陈维民. 直接甲醇燃料电池电催化剂稳定性研究, 大连: 大连化学物理研究所, 2007)
[6]	Roen L. M., Paik C. H., Jarvi T. D., Electrochem. Solid St., 2004, 7(1), A19—A22
[7]	Liu Z., Lee J. Y., Chen W., Han M., Gan L. M., Langmuir, 2004, 20(1), 181—187
[8]	He Z., Chen J., Liu D., Zhou H., Kuang Y., Diam. Relat. Mater., 2004, 13(10), 1764—1770
[9]	Watanabe M. A., Motoo S., J. Electroanal. Chem. Interfacial Electrochem., 1975, 60(3), 267—273
[10]	Chen W., Sun G., Guo J., Zhao X., Yan S., Tian J., Tang S., Zhou Z., Xin Q., Electrochim. Acta, 2006, 51(12), 2391—2399
[11]	Uhm S., Lee J., J. Ind. Eng. Chem., 2009, 15(5), 661—664
[12]	Mao Q., Jing W. Y., Shi Y., Prog. Chem., 2017, 29(2/3), 210—215
	(毛庆, 景维云, 石越. 化学进展, 2017, 29(2/3), 210—215)
[13]	Mueller J. T., Urban P. M., J. Power Sources, 1998, 75(1), 139—143
[14]	Liu J., Zhou Z., Zhao X., Xin Q., Sun G., Yi B., Phys. Chem. Chem. Phys., 2004, 6(1), 134—137
[15]	Wang Z. B., Yin G. P., Shao Y. Y., Yang B. Q., Shi P. F., Feng P. X., J. Power Sources, 2007, 165(1), 9—15
[16]	Krewer U., Christov M., Vidakovic T., Sundmacher K., J. Electroanal. Chem., 2006, 589(1), 148—159
[17]	Piela P., Fields R., Zelenay P., J. Electrochem. Soc., 2006, 153(10), A1902—A1913
[18]	Wagner N., Schulze M., Electrochim. Acta, 2003, 48(25/26), 3899—3907
[19]	Krewer U., Kamat A., Sundmacher K., J. Electroanal. Chem., 2007, 609(2), 105—119
[20]	Vidakovic'-Koch T. R., Panic' V. V., Andric' M., Petkovska M., Sundmacher K., J. Phys. Chem. C, 2011, 115(35), 17341—17351
[21]	Panic V. V., Vidakovic'-Koch T. R., Andric M., Petkovska M., Sundmacher K., J. Phys. Chem. C, 2011, 115(35), 17352—17358
[22]	Kadyk T., Hanke-Rauschenbach R., Sundmacher K., Int. J. Hydrogen Energy, 2012, 37(9), 7689—7701
[23]	Ramschak E., Method for Monitoring the Operational State of a Fuel Cell Stack, US 2006008788A1, 2009-05-12
[24]	McDonald T. J., Adler S., ECST., 2012, 45(1), 429—439
[25]	Mao Q., Krewer U., Electrochim. Acta, 2012, 68, 60—68
[26]	Ramschak E., Peinecke V., Prenninger P., Schaffer T., Hacker V., J. Power Sources, 2006, 157(2), 837—840
[27]	Mao Q., Krewer U., Electrochim. Acta, 2013, 103, 188—198
[28]	Bensmann B., Petkovska M., Vidakovic'-Koch T., Hanke-Rauschenbach R., Sundmacher K., J. Electrochem. Soc., 2010, 157(9), B1279—B1289
[29]	Mao Q., Krewer U., Hanke-Rauschenbach R., Electrochem. Commun., 2010, 12(11), 1517—1519