期刊
ELECTROCHIMICA ACTA
卷 176, 期 -, 页码 1044-1053出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.electacta.2015.07.048
关键词
Square wave voltammetry; Microelectrodes; Unequal diffusion coefficients; Coupled chemical equilibria; Differential double pulse voltammetry
资金
- Ministerio de Economia y Competitividad [CTQ2012-36700]
- European Regional Development Fund
- Fundacion Seneca de la Region de Murcia under the III PCTRM Programme [18968/JLI/13]
- European Union Seventh Framework Programme-Marie Curie COFUND under UMU Incoming Mobility Programme ACTion (U-IMPACT) [267143]
Square wave voltammetry (SWV) at disc and hemispherical microelectrodes is studied when the electroactive species show different diffusivities and/or take part in chemical equilibria in solution, under both transient and steady state conditions. Despite the use of microelectrodes, experiments in pulse techniques such as SWV frequently correspond to transient conditions since the pulse duration are typically very short (<100ms, f>5 Hz). As will be shown, under such conditions the case of unequal diffusion coefficients gives rise to a complex behaviour of the SWV peak, the features of which deviate from the theory and criteria already established under the assumption of equal diffusion coefficients. Also, the theoretical treatment is notably more difficult and no analytical solution has been deduced for multipulse techniques. The effects of coupled chemical equilibria and, particularly, of unequal diffusion coefficients on SWV will be described in depth as a function of the electrode size and shape and they will be compared with those observed in differential double pulse voltammetry (DDPV). The main discrepancies in the peak height, width and position with respect to the case of equal diffusion coefficients will be studied. Also, appropriate methodologies and experimental conditions will be discussed for the determination of formal potentials and equilibrium constants. (C) 2015 Elsevier Ltd. All rights reserved.
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