法拉第吸脱附偶联过程循环伏安行为的有限元分析

doi:10.13208/j.electrochem.190411

摘要/Abstract

摘要：

法拉第吸脱附偶联过程的电化学行为较为复杂,难以定量获得其表界面反应动力学信息. 本文通过COMSOL有限元软件对法拉第吸脱附偶联过程的循环伏安行为进行数值分析,研究了反应物或产物不同吸附条件下的循环伏安行为. 结果表明：当反应物或产物弱吸附时,可通过阴、阳极峰电流之差实现饱和吸附量的定量表征. 随着吸附平衡常数的增大,反应由弱吸附向强吸附过渡,峰电流由扩散峰与吸脱附峰相互重叠过渡到相互分离的吸脱附“前波”或“后波”特征. 该吸脱附特征峰的形状和位置与电势依赖的吸附平衡常数有关. 吸附平衡常数及其电势依赖程度越大,吸脱附峰偏离扩散峰越远,吸脱附峰越尖锐. 该模型为法拉第吸脱附偶联过程的循环伏安研究提供了一种定量研究方法,能够帮助研究者从复杂的吸脱附伏安行为中定量获得饱和吸附量和吸附平衡常数等信息,并对涉及吸脱附的电催化研究具有一定指导意义.

关键词: 法拉第吸脱附, 异相电子转移, 电极过程, 循环伏安, 有限元模拟

Abstract:

Heterogeneous electron transfer (HET) coupled with Faradic adsorption/desorption is the fundamental processes involved in hydrogen evolution reaction, oxygen reduction reaction, carbon dioxide reduction reaction, and methanol oxidation reaction. However, the electrochemical behaviors of HET coupled with Faradic adsorption/desorption are complicated, and difficult to get the interface reaction kinetics quantitatively. In this paper, finite element method was adopted to simulate the cyclic voltammetric behaviors of HET coupled with Faradic adsorption/desorption processes by using the Fick’s second law and Langmuir isotherm. The cyclic voltammograms when reactant or product adsorbed weakly or strongly were simulated, and they agreed well with the classical results. In addition, taking the reactant adsorption for example, the effects of scanning rate, saturated adsorption and adsorption equilibrium constant on cyclic voltammograms were investigated. The simulation demonstrates that weak adsorption can be magnified with the increasing scanning rate, and the peak current changes gradually from being proportional to the square root of scanning rate to being proportional to the scanning rate. The difference between anodic and cathodic peak currents is linearly related to saturated adsorption. Therefore, the quantitative characterization of saturated adsorption is realized by correlating the difference between anodic and cathodic peak currents to the saturated adsorption. With the increasing adsorption equilibrium constant, the weak adsorption transfers to strong adsorption, and the adsorption/desorption peaks separate from diffusion peaks to form prepeaks or postpeaks. The potential-dependent adsorption equilibrium constant was also simulated, which demonstrates that it can further change the shape and position of adsorption/desorption peaks. The quantitative method based on this model can help researchers to obtain saturated adsorption and adsorption equilibrium constant quantitatively from the cyclic voltammograms coupled with Faradic adsorption/desorption processes. The simulation can also help researchers to understand the different cyclic voltammetric behaviors between surface processes and diffusion processes, and would be constructive for the study of electrocatalysis involving adsorption/desorption processes.

Key words: adsorption/desorption, heterogeneous electron transfer, electrode process, cyclic voltammetry, finite element simulation

中图分类号:

O646.54

郭佳瑶, 陈煅, 张杰, 詹东平. 法拉第吸脱附偶联过程循环伏安行为的有限元分析[J]. 电化学（中英文）, 2020, 26(2): 281-288.

GUO Jia-yao, CHEN Duan, ZHANG Jie, ZHAN Dong-ping. Cyclic Voltammetry Coupled with Faradic Adsorption/Desorption Processes: A Finite Element Simulation[J]. Journal of Electrochemistry, 2020, 26(2): 281-288.

导出引用管理器 EndNote|Ris|BibTeX

链接本文: https://electrochem.xmu.edu.cn/CN/10.13208/j.electrochem.190411

https://electrochem.xmu.edu.cn/CN/Y2020/V26/I2/281

图/表 6

图1

表1

图2

图3

图4

图5

参考文献 29

[1]	Coleman E J, Co A C . The complex inhibiting role of surface oxide in the oxygen reduction reaction[J]. ACS Catalysis, 2015,5(12):7299-7311. doi: 10.1021/acscatal.5b02122 URL
[2]	Adzic R R, Tripkovic A V, O'Grady W E . Structural effects in electrocatalysis[J]. Nature, 1982,296(5853):137-138. doi: 10.1038/296137a0 URL
[3]	Wang W, Zhang J, Wang F F , et al. Mobility and reactivity of oxygen adspecies on platinum surface[J]. Journal of the American Chemical Society, 2016,138(29):9057-9060. doi: 10.1021/jacs.6b05259 URL
[4]	Zhou X S, Dong Z R, Zhang H M , et al. Self-assembly of a Rh(I) complex on Au(111) surfaces and its electrocatalytic activity toward the hydrogen evolution reaction[J]. Langmuir, 2007,23(12):6819-6826. doi: 10.1021/la062949q URL
[5]	Li K, Peng B S, Peng T Y . Recent advances in heterogeneous photocatalytic CO₂ conversion to solar fuels[J]. ACS Catalysis, 2016,6(11):7485-7527. doi: 10.1021/acscatal.6b02089 URL
[6]	Sun S G( 孙世刚), Chen S L( 陈胜利 ). Electrocatalysis[M]. Chemical Industry Press Co., Ltd.( 化学工业出版社), 2016.
[7]	Yang J H, Cooper J K, Toma F M , et al. A multifunctional biphasic water splitting catalyst tailored for integration with high-performance semiconductor photoanodes[J]. Nature Materials, 2016,16(3):335-341.
[8]	Merki D, Vrubel H, Rovelli L , et al. Fe, Co, and Ni ions promote the catalytic activity of amorphous molybdenum sulfide films for hydrogen evolution[J]. Chemical Science, 2012,3(8):2515-2525.
[9]	Yin Y, Han J C, Zhang Y M , et al. Contributions of phase, sulfur vacancies, and edges to the hydrogen evolution reaction catalytic activity of porous molybdenum disulfide nanosheets[J]. Journal of the American Chemical Society, 2016,138(25):7965-7972.
[10]	Li G Q, Zhang D, Qiao Q , et al. All the catalytic active sites of MoS₂ for hydrogen evolution[J]. Journal of the American Chemical Society, 2016,138(51):16632-16638.
[11]	Bard A J, Faulkner L R . Electrochemical methods: Fundamentals and applications(2nd Ed.)[M]. New York, Wiley, 2001.
[12]	Jiang Y F, Jiang B, Yang L K , et al. Determination of adsorbed species of hypophosphite electrooxidation on Ni electrode by in situ infrared with shell-isolated nano-particle-enhanced Raman spectroscopy[J]. Electrochemistry Communications, 2014,48:5-9.
[13]	Li C Y, Chen S Y, Zheng Y L , et al. In-situ electrochemical shell-isolated Ag nanoparticles-enhanced Raman spectroscopy study of adenine adsorption on smooth Ag electrodes[J]. Electrochimica Acta, 2016,199:388-393.
[14]	Li J F, Zhang Y J, Rudnev A V , et al. Electrochemical shell-isolated nanoparticle-enhanced raman spectroscopy: correlating structural information and adsorption processes of pyridine at the Au(hkl) single crystal/solution interface[J]. Journal of the American Chemical Society, 2015,137(6):2400-2408. doi: 10.1021/ja513263j URL
[15]	Chen C H, Meadows K E, Cuharuc A , et al. High resolution mapping of oxygen reduction reaction kinetics at polycrystalline platinum electrodes[J]. Physical Chemistry Chemical Physics, 2014,16(34):18545-18552. doi: 10.1039/c4cp01511h URL
[16]	Zuliani C, Walsh D A, Keyes T E , et al. Formation and growth of oxide layers at platinum and gold nano- and microelectrodes[J]. Analytical Chemistry, 2010,82(17):7135-7140.
[17]	Su Y Z, Yan J W, Li M G , et al. Adsorption of solvent cations on Au(111) and Au(100) in alkylimidazolium-based ionic liquids-worm-like versus micelle-like structures[J]. Zeitschrift Fur Physikalische Chemie-International Journal of Research in Physical Chemistry & Chemical Physics, 2012,226(9/10):979-994.
[18]	Tang Y G, Yan J W, Zhu F , et al. Comparative electrochemical scanning tunneling microscopy study of nonionic fluorosurfactant zonyl FSN self-assembled monolayers on Au(111) and Au(100): a potential-induced structural transition[J]. Langmuir, 2011,27(3):943-947.
[19]	Rodríguez-López J, Alpuche-Avilés M A, Bard A J . Interrogation of surfaces for the quantification of adsorbed species on electrodes: Oxygen on gold and platinum in neutral media[J]. Journal of the American Chemical Society, 2008,130(50):16985-16995.
[20]	Liang Z X, Ahn H S, Bard A J . A study of the mechanism of the hydrogen evolution reaction on nickel by surface interrogation scanning electrochemical microscopy[J]. Journal of the American Chemical Society, 2017,139(13):4854-4858.
[21]	Ahn H S, Bard A J . Assessment of the stability and operability of cobalt phosphide electrocatalyst for hydrogen evolution[J]. Analytical Chemistry, 2017,89(16):8574-8579. doi: 10.1021/acs.analchem.7b02799 URL
[22]	Wopschall R H, Shain I . Effects of adsorption of electroactive species in stationary electrode polarography[J]. Analytical Chemistry, 1967,39(13):1514-1527.
[23]	Cuharuc A S, Zhang G, Unwin P R . Electrochemistry of ferrocene derivatives on highly oriented pyrolytic graphite (HOPG): quantification and impacts of surface adsorption[J]. Physical Chemistry Chemical Physics, 2016,18(6):4966-4977.
[24]	Zhang J, Jia J C, Han L H , et al. Kinetic investigation on the confined etching system of n-type gallium arsenide by scanning electrochemical microscopy[J]. Journal of Physical Chemistry C, 2014,118(32):18604-18611. doi: 10.1021/jp5056446 URL
[25]	Güell A G, Ebejer N, Snowden M E , et al. Structural correlations in heterogeneous electron transfer at monolayer and multilayer graphene electrodes[J]. Journal of the American Chemical Society, 2012,134(17):7258-7261.
[26]	Zheng Q, Huang X M, Liu Y , et al. Electrochemical quantification of intermolecular hydrogen bonding between ferrocenemethanol and 3-mercaptopropanoic acid on gold[J]. Journal of Physical Chemistry C, 2017,121(40):22123-22129.
[27]	Kobayashi K, Fujisaki F, Yoshimine T , et al. An analysis of the voltammetric adsorption waves of methyl viologen[J]. Bulletin of the Chemical Society of Japan, 1986,59(12):3715-3722.
[28]	He P X, Crooks R M, Faulkner L R . Adsorption and electrode reactions of disulfonated anthraquinones at mercury electrodes[J]. Journal of Physical Chemistry, 1990,94(3):1135-1141.
[29]	Zheng Q, Zhang J, Yang Y F , et al. Regulating the intermolecular hydrogen bonding: The reversible assembly and disassembly in the diffusion layer[J]. Journal of The Electrochemical Society, 2017,164(2):H97-H103.

Parameter	Value
D_i	7.4 × 10^-6 cm²·s^-1
E⁰	0.19 V vs. SCE
r_e	1 mm
n	1
α	0.5
C_Ox^*	0 mmol·L^-1
C_Re^*	0.5 mmol·L^-1
k⁰	5 cm·s^-1