Solvent effects on the electrode kinetics of simple redox couples: Investigations on the electrochemical behaviour of the V(III)/V(II) system in water + acetonitrile mixtures |
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| Affiliation: | 1. Institute of Green Chemistry and Energy, Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055, China;2. Key Lab of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing, 100084, China;3. School of Applied Chemistry and Biological Technology, Shenzhen Polytechnic, Shenzhen, 518055, China;4. Shenzhen Key Laboratory of Special Functional Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China;1. Tiradentes University, Avenida Murilo Dantas 300, 49032-490 Aracaju, Sergipe, Brazil;2. Institute of Technology and Research, Avenida Murilo Dantas 300, 49032-490 Aracaju, Sergipe, Brazil;3. Departament of Chemical Engineering, Federal University of Paraná, Polytechnic Center, Avenida Coronel Francisco H. dos Santos, s/n, Jardim das Américas, 81531-990 Curitiba, Paraná, Brazil;4. CICECO – Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal;1. Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland;2. A.N Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow 119991, Russia |
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| Abstract: | Parallel optical and electrochemical studies on the V(III)/V(II) system in H2O + acetonitrile (AN) + CF3SO3H mixtures have been performed. It was found, on the basis of the spectra of vanadium ions in the visible range, that V(III) was totally hydrated in mixtures up to xAN ⋍ 0.6 while V(II) was specifically solvated by AN molecules, even at a molar fraction of acetonitrile in H2O + AN mixtures as low as 0.02. In agreement with this, the formal potentials of the V(III)/V(II) system expressed versus the ferrocene electrode move to less negative potentials with an increase in AN concentration.Straightforward correlations of the electrode kinetics of the V(III)/V(II) system at a mercury electrode in H2O + AN mixtures with both the electrode surface coverage by AN molecules and the resolvation of vanadium ions in the bulk solution were found. |
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