Jännsch Yannick, Hämmerle Martin, Leung Jane J, Simon Elfriede, Fleischer Maximilian, Moos Ralf
Department for Functional Materials, University of Bayreuth 95440 Bayreuth Germany
Siemens Energy Global GmbH & Co. KG Otto-Hahn-Ring 6 81739 Muenchen Germany.
RSC Adv. 2021 Aug 20;11(45):28189-28197. doi: 10.1039/d1ra05345k. eCollection 2021 Aug 16.
With the transfer of the electrochemical CO-reduction from academic labs towards industrial application, one major factor is the increase in current density. This can be achieved the usage of a gas diffusion electrode. It allows for electrochemical reactions at the three-phase boundary between gaseous CO, liquid electrolyte and electrocatalyst. Thus, current densities in commercially relevant magnitudes of 200 mA cm and beyond can be reached. However, when increasing the current density one faces a new set of challenges, unknown from low current experiments. Here, we address the issue of gas evolution causing a local increase in resistance and the impact on the operation of flow cells with gas diffusion electrodes. We set up a simple simulation model and compared the results with experiments on a real setup. As a result, the gas evolution's strong impact on current-, potential- and resistance-distributions along the flow axis can be described. Main consequence is that the positioning of the reference electrode has a significant effect on the locally measured IR-drop and thus on the measured or applied potential. Therefore, data from different setups must be compared with great care, especially with respect to the potentials, on which the cell is operated.
随着电化学CO还原从学术实验室向工业应用的转变，一个主要因素是电流密度的增加。这可以通过使用气体扩散电极来实现。它允许在气态CO、液体电解质和电催化剂之间的三相边界处发生电化学反应。因此，可以达到商业相关量级的200 mA/cm及以上的电流密度。然而，当增加电流密度时，人们面临着一组新的挑战，这些挑战在低电流实验中是未知的。在这里，我们解决了气体析出导致局部电阻增加以及对带有气体扩散电极的流动电池运行的影响这一问题。我们建立了一个简单的模拟模型，并将结果与实际装置上的实验进行了比较。结果表明，可以描述气体析出对沿流动轴的电流、电位和电阻分布的强烈影响。主要结果是，参比电极的位置对局部测量的IR降有显著影响，从而对测量或施加的电位有显著影响。因此，必须非常谨慎地比较来自不同装置的数据，尤其是关于电池运行所依据的电位的数据。
