Biermann Michael, Leppin Christian, Langhoff Arne, Ziemer Thorben, Rembe Christian, Johannsmann Diethelm
Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Straße 4, D 38678 Clausthal-Zellerfeld, Germany.
Institute of Electrical Information Technology, Clausthal University of Technology, Leibnizstraße 28, D 38678 Clausthal-Zellerfeld, Germany.
Analyst. 2024 Mar 25;149(7):2138-2146. doi: 10.1039/d3an02210b.
Using a precise electrochemical quartz crystal microbalance (EQCM), it was shown that electrogravimetry can be carried out with microelectrode arrays (MEAs). MEAs were prepared on the resonator surface by coating it with a thin polymer layer containing holes, where the holes constitute the microelectrodes. The preparation procedures, their benefits, and their limitations are discussed. Microelectrode-based electrogravimetry is challenging because the reduced active area reduces the QCM signal. It is still feasible. This work is limited to linear voltage ramps (as opposed to steps). The processes chosen for demonstration were the electrodeposition/stripping of copper and the redox cycling of methyl viologen dichloride (MVC). The current trace often showed microelectrodic behavior, depending on the sweep rate. For the case of copper deposition, the mass transfer rate was proportional to the electric current. For the case of MVC, the electric current showed a plateau at the ends of the current-voltage diagram, but the mass transfer rate did not change. The difference can be explained by adsorption and desorption going into saturation at the two ends of the voltage range. Based on whether or not a microelectrodic gravimetric signal is seen, it can be stated whether the mass transfer is closely linked to the current. Further advantages of the microelectrode-based EQCM are an improved access to fast processes, reduced effects of double layer recharging, and the possibility to work at a low electrolyte support.
使用精密电化学石英晶体微天平（EQCM）表明，可以使用微电极阵列（MEA）进行电重量分析。通过在谐振器表面涂覆一层含有孔洞的薄聚合物层来制备MEA，其中孔洞构成微电极。讨论了制备过程、其优点和局限性。基于微电极的电重量分析具有挑战性，因为活性面积减小会降低QCM信号。但它仍然是可行的。这项工作仅限于线性电压扫描（与阶跃相对）。选择用于演示的过程是铜的电沉积/溶出以及二氯甲基紫精（MVC）的氧化还原循环。电流轨迹通常表现出微电极行为，这取决于扫描速率。对于铜沉积的情况，传质速率与电流成正比。对于MVC的情况，电流在电流-电压图的两端呈现出平台，但传质速率没有变化。这种差异可以通过在电压范围两端吸附和解吸达到饱和来解释。基于是否观察到微电极重量分析信号，可以判断传质是否与电流密切相关。基于微电极的EQCM的进一步优点是能够更好地研究快速过程、减少双层充电的影响以及在低电解质支持下工作的可能性。
