铁电极电还原溴化钠甲醇溶液反应动力学和机理

Kinetics and Mechanism toward Electrochemical Reductions of Sodium Bromide and Methanol over Iron Electrodes

研究溴化钠(NaBr)甲醇溶液在铁电极上电还原反应动力学和机理对于二茂铁电化学制备、非水体系中二氧化碳(CO_2)的电还原和有机电合成等领域具有实用价值和科学意义,但对此未见详细报道.本文采用极化曲线和电化学阻抗谱等技术详细地研究了该体系的电还原动力学和机理.结果表明,反应物为甲醇,而Na^+只起导电作用,电极电位是该体系中唯一状态变量,其对甲醇电还原速率常数的影响符合阿仑尼乌斯唯象方程式,电还原过程不受扩散极化控制,溶液欧姆极化是主要极化形式,甲醇电还原依法拉第定律计量地产生氢气,反应活化能约为26.2 kJ·mol^(-1).

It is of technological value and scientific interest to the electro-synthesis of ferrocene,conversion of carbon dioxide（CO2） and organic electro-synthesis in non-aqueous solutions by investigating the kinetics and mechanism toward electrochemical reductions of sodium bromide（NaBr） and methanol over iron electrodes.However,few reports in the related researches are available.In this article,the kinetics and mechanism toward electrochemical reductions of Na Br and methanol over iron electrodes were examined in detail by carrying out the polarization curve and electrochemical impedance spectroscopic measurements.The results showed that methanol was the reactant,while Na＋ions were functioned only as conducting species;the electrode potential was the only status variable,and its impact on the rate constants of the electro-reduction of methanol followed classic Arrhenius’s equation;the reduction was not limited by concentration diffusion,but mainly by the Ohmic po larization;the amount of H2 gas production obeyed the Faraday’s law and the activation energy was evaluated to be 26.2 kJ·mol-1.