Generating Oscillatory Behavior by Applying a Magnetic Field during Electrocatalytic Oxidation of Glycerol
Generating Oscillatory Behavior by Applying a Magnetic Field during Electrocatalytic Oxidation of Glycerol
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DOI：
10.1021/acs.jpcc.2c05145
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发表时间：
2022-10
期刊：
影响因子：
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通讯作者：
Rui Gao;Mohamad S. Kodaimati;Kaitlyn M. Handy;Samuel E. Root;G. Whitesides
中科院分区：
文献类型：
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作者：
Rui Gao;Mohamad S. Kodaimati;Kaitlyn M. Handy;Samuel E. Root;G. Whitesides
：这项工作演示了电催化过程中磁场的应用如何影响电极表面反应物和产物的传输，并在某些条件下，在电流实验中产生复杂的振荡行为。在甘油的电催化氧化 (EOG) 过程中，洛伦兹力作用于水合氢离子和氢氧根离子电流，产生流体对流，从而增强甘油和甘油醛的质量传递。粒子成像测速表明，对流流体流场与溶液粘度呈非线性关系（由甘油浓度决定，范围为 2.5% 至 40% v/v，粘度范围为 1.3 – 5.3 mPa s）。流体流速对电解质粘度的非线性依赖性在 EOG 期间产生延时负反馈并导致化学振荡。这种延时反馈是由于两个耦合步骤造成的：（i）甘油的氧化迅速降低了阳极附近电解质的粘度，（ii）低粘度磁场增加了传质速率，从而增加了阳极附近电解质的粘度（通过增加甘油的浓度）。这些化学振荡可用于将 EOG 对甘油酸的选择性提高 2.1 倍。这项工作重点结合流体流动分析、旋转盘电极实验和电化学模拟来研究磁场对 EOG 的影响。
: This work demonstrates how the application of a magnetic field during electrocatalysis can affect the transport of reactants and products at the electrode surface and, under certain conditions, generate complex, oscillatory behavior in amperometric experiments. During the electrocatalytic oxidation of glycerol (EOG), the Lorentz force acts upon hydronium and hydroxide ionic currents to produce fluidic convection, which serves to enhance the mass transport of glycerol and glyceraldehyde. Particle imaging velocimetry shows that the convective fluid flow field depends nonlinearly on the viscosity of the solution (dictated by the concentration of glycerol, which ranged from 2.5% to 40% v/v, to give a viscosity range of 1.3 − 5.3 mPa s). The nonlinear dependence of velocity of the fluid flow on the viscosity of the electrolyte generates time-delayed negative feedback during EOG and results in chemical oscillations. This time-delayed feedback is due to two coupled steps: (i) oxidation of glycerol rapidly decreases the viscosity of the electrolyte near the anode and (ii) at low viscosities magnetic fields increase the rate of mass transport, which subsequently increases the viscosity of the electrolyte near the anode (by increasing the concentration of glycerol). These chemical oscillations can be used to enhance the selectivity of EOG to glyceric acid by a factor of 2.1. This work focuses on the effects of magnetic fields on EOG using a combination of fluid flow analysis, rotating-disk electrode experiments, and electrochemical simulations.