Novev Javor K, Compton Richard G
Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford, OX1 3QZ, UK.
Phys Chem Chem Phys. 2016 Nov 21;18(43):29836-29846. doi: 10.1039/c6cp06121d. Epub 2016 Oct 19.
Electrochemical experiments, especially those performed with scanning electrochemical microscopy (SECM), are often carried out without taking special care to thermostat the solution; it is usually assumed that its temperature is homogeneous and equal to the ambient. The present study aims to test this assumption via numerical simulations of the heat transfer in a particular system - the typical measurement cell for SECM. It is assumed that the temperature of the solution is initially homogeneous but different from that of its surroundings; convective heat transfer in the solution and the surrounding air is taken into account within the framework of the Boussinesq approximation. The hereby presented theoretical treatment indicates that an initial temperature difference of the order of 1 K dissipates with a characteristic time scale of ∼1000 s; the thermal equilibration is accompanied by convective flows with a maximum velocity of ∼10 m s; furthermore, the temporal evolution of the temperature profile is influenced by the sign of the initial difference. These results suggest that, unless the temperature of the solution is rigorously controlled, convection may significantly compromise the interpretation of data from SECM and other electrochemical techniques, which is usually done on the basis of diffusion-only models.
电化学实验，尤其是那些使用扫描电化学显微镜（SECM）进行的实验，通常在未特别注意对溶液进行恒温处理的情况下开展；通常假定溶液温度均匀且等于环境温度。本研究旨在通过对一个特定系统——SECM的典型测量池内的热传递进行数值模拟来检验这一假设。假定溶液温度最初是均匀的，但与周围环境温度不同；在布辛涅斯克近似框架内考虑了溶液和周围空气中的对流热传递。此处给出的理论处理表明，量级为1 K的初始温差以约1000 s的特征时间尺度消散；热平衡伴随着最大速度约为10 m/s的对流；此外，温度分布的时间演化受初始温差符号的影响。这些结果表明，除非严格控制溶液温度，否则对流可能会严重影响基于仅扩散模型的SECM和其他电化学技术数据的解释。
