Electrode Kinetics and Mechanism of Iodine Reduction in the Room-Temperature Ionic Liquid [C4mim][NTf2]

详细信息    查看全文

• 作者：Emma I. Rogers ; Ian Streeter ; Leigh Aldous ; Christopher Hardacre ; Richard G. Compton
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：July 24, 2008
• 年：2008
• 卷：112
• 期：29
• 页码：10976-10981
• 全文大小：171K
• 年卷期：v.112,no.29(July 24, 2008)
• ISSN：1932-7455

文摘

The fast electrochemical reduction of iodine in the RTIL 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C₄mim][NTf₂], is reported and the kinetics and mechanism of the process elucidated. Two reduction peaks were observed. The first reduction peak is assigned to the process pan class="NLM_disp-formula" id="eqA1"> pan> The second reduction peak is assigned to the process pan class="NLM_disp-formula" id="eqA2"> pan> A diffusion coefficient of 6.6 × 10p>−11p> mp>2p> sp>−1p> (298 K) is inferred for I₂ in [C₄mim][NTf₂] with a solubility of 1.70 mM. A mechanistic study was undertaken using a digital simulation program based on the mechanism pan class="NLM_disp-formula" id="eqA3"> pan> pan class="NLM_disp-formula" id="eqA4"> pan> and simulation of the first reduction wave allowed extraction of various kinetic parameters including the diffusion coefficients for I₂, I₃p>−p>, and Ip>−p>, rate constants for the homogeneous process (k_f,hom and k_b,hom), and the heterogeneous rate constants k_ap>′p> and k_bp>′p>, and the associated transfer coefficients. The electrode process was found to be consistent with the following form of Butler−Volmer kinetics pan class="NLM_disp-formula" id="eqA5"> pan> The mechanistic basis for this rate law is discussed.