旋转圆盘电极（RDE）体系主要用于低溶解度反应物的电极过程动力学研究. 在利用RDE技术研究不可逆电极反应动力学时，人们常利用Koutecky-Levich方程排除传质的影响，从总电流估算反应的动力学电流. 由于K-L方程是建立在系统满足稳态扩散模型的基础上，实际运用时如果体系偏离稳态扩散，就有可能对估算的动力学参数造成很大误差. 本文以氧气在多晶铂电极上的还原反应为例系统地估算了不同氧气浓度与电极转速下的误差，结果表明低氧气浓度与低圆盘转速的情况不满足稳态扩散条件，若此时仍根据K-L方程利用外推法进行分析，误差可达30%. 因此作者建议，在RDE体系中利用K-L方程估算动力学参数时，最好忽略低浓度与低转速下的数据，直接使用较高浓度与较高转速下的数据进行计算与分析.
Rotating disk electrode system is mainly used to study the kinetics of reactions whose reactants have very low solubility in the electrolyte. For an irreversible reaction, Koutecky-Levich equation (K-L Eq.) is frequently used to deduce the kinetic current ik). Since K-L Eq. is derived based on the assumption that a system should conform the steady-state diffusion conditions, the data recoded from the actual system which deviates from such a condition, great error may be induced for the ik estimated. In this work, polarization curves for oxygen reduction reaction at polycrystalline Pt electrode recorded in solutions with various O2 concentrations and under various electrode rotation speeds have been analyzed systematically. Our analysis reveals that an error of 30% may be introduced by extrapolation to infinite rotation speed in solution with low O2 concentration or by including the data recorded under very slow electrode rotation speeds. The origins of the error and the ways to avoid such error are discussed.
[1] Gottesfeld S. Electrocatalysis of oxygen reduction in polymer electrolyte fuel cells, a brief history and a critical examination of present theory and diagnostics[M]//, Koper M (Ed.), Fuel cell catalysis: A surface science approach. New Jersey: John Wiley & Sons, Inc., Hoboken, 2009: Chapter 9.
[2] Markovic N M, Schmidt T J, Stamenkovic V, et al. Oxygen reduction reaction on pt and pt bimetallic surfaces: A selective review[J]. Fuel Cells, 2001, 1(2): 105-116.
[3] Markovic N, Gasteiger H, Ross P N. Kineticsof oxygen reduction on Pt(hkl) electrodes: Implications for the crystallite size effect with supported Pt electrocatalysts[J]. Journal of The Electrochemical Society, 1997, 144(5): 1591-1597.
[4] Markovic N M, Gasteiger H A, Ross P N. Oxygen reduction on platinum low-index single crystal surfaces in sulfuric acid solution-rotating ring-Pt(HKL) disk studies[J]. Journal of Physical Chemistry, 1995, 99(11): 3411-3415.
[5] Zurilla R W, Sen R K, Yeager E. The Kinetics of the oxygen reduction reaction on gold in alkaline solution[J]. Journal of The Electrochemical Society, 1978, 125: 1103.
[6] Paulus U A, Schmidt T J, Gasteiger H A, et al. Oxygen reduction on a high-surface area Pt/Vulcan carbon catalyst: A thin-film rotating ring-disk electrode study[J]. Journal of Electroanalytical Chemistry, 2001, 495(2): 134-145.
[7] Schmidt T J, Paulus U A, Gasteiger H A, et al. The oxygen reduction reaction on a Pt/carbon fuel cell catalyst in the presence of chloride anions[J]. Journal of Electroanalytical Chemistry, 2001, 508(1/2): 41-47.
[8] Liao L W. Methodology and electrocatalysts for oxygen reduction reaction[D]. Hefei: University of Science and Technology of China, 2013.
[9] Masa J, Batchelor-McAuley C, Schuhmann W, et al. Koutecky-Levich analysis applied to nanoparticle modified rotating disk electrodes: Electrocatalysis or misinterpretation?[J]. Nano Research, 2014, 7(1): 71-78.
[10] van der Vliet D，Strmcnik D S，Wang C，et al. On the importance of correcting for the uncompensated ohmic resistance in model experiments of the oxygen reduction reaction[J]. Journal of Electroanalytical Chemistry, 2010, 647(1): 29-34.
[11] Bard A J, Faulkner L R. Electrochemical methods fundamentals and applicantions[M]. Chemical Industry Press(化学工业出版社), 2005: 230-245.
[12] Chen Y X，Li M F，Liao L W，et al. A thermostatic cell with gas diffusion electrode for oxygen reduction reaction under fuel cell relevant conditions[J]. Electrochemistry Communications, 2009, 11(7): 1434-1436.
[13] Yano H, Higuchi E, Uchida H, et al. Temperature dependence of oxygen reduction activity at Nafion-coated bulk Pt and Pt/carbon black catalysts[J]. Journal of Physical Chemistry B, 2006, 110(33): 16544-16549.
[14] Gasteiger H A, Kocha S S, Sompalli B, et al. Activity benchmarks and requirements for Pt, Pt-alloy, and non-Pt oxygen reduction catalysts for PEMFCs[J]. Applied Catalysis B-Environmental, 2005, 56(1/2): 9-35.
[15] Chen D, Tao Q, Liao L W, et al. Determining the active surface area for various platinum electrodes[J]. Electrocatalysis, 2011, 2(3): 207-219.
[16] Liao L W（廖玲文）, Chen D（陈栋）, Chen Y X（陈艳霞）, et al. Effect of catalyst loading on the evaluation of kinetic parameters of gas electrode reactions by using thin film rotating disk electrode method[J]. Scientia Sinica Chimica(中国科学). 2013, 43(2): 178-184.
