Model-based Analysis of Oxygen and CO2 Reduction Reaction Kinetics on Silver Electrodes

本课题研究了多晶银电极上氧(ORR)和二氧化碳还原(CO2R)的动力学。其目的是提高对非典型条件下的电化学反应动力学的基本理解，例如在高浓度溶液(ORR)和存在副反应(CO2R)的情况下。此外，该项目的结果将被用来了解ORR和CO2R在工业气体扩散电极中的局限性。研究这一过程的方法是非线性频率响应分析(NFRA)。考虑到科学界对非线性动力学方法的高度兴趣，本项目的另一个目标是进一步发展NFRA方法。通过系统地研究银电极(ORR，HER，CO2R)上的各种电化学反应是可能的，这些电化学反应涵盖了广泛的复杂的电化学反应机理(包括电化学、化学步骤和之前在电解液中的反应)。ORR和CO2R反应包括中间产物(过氧化氢)或副产物(H2)的形成，与预期产物(ORR或CO2R分别为OH和CO)相比，这些中间产物或副产物(H2)的选择性降低。因此，证明周期性操作是否会影响CO2R的产物选择性是很有意义的，这不仅具有实际意义，而且具有根本性的重要性。

In this project kinetics of oxygen (ORR) and carbon dioxide reduction (CO2R) on polycrystalline silver electrodes are studied. The aim is to improve the basic understanding of the kinetics of electrochemical reactions under atypical conditions, e.g. in highly concentrated solutions (ORR) and in presence of side reactions (CO2R). In addition, the results of this project will be used to understand the limitations of ORR and CO2R in technical gas diffusion electrodes. The method of choice to study this processes is nonlinear frequency response analysis (NFRA). Having in mind high interest of scientific community in nonlinear dynamic methods, another objective of this project is to further develop NFRA method. This will be possible through the systematic investigation of various electrochemical reactions on a silver electrode (ORR, HER, CO2R), which cover a wide range of complex electrochemical reaction mechanisms (with electrochemical, chemical steps and previous reactions in electrolytes). The ORR and CO2R reactions include the formation of intermediate (hydrogen peroxide) or by-products (H2) which reduce selectivity compared to the desired product (OH and CO for ORR or CO2R respectively). Therefore it is interesting to demonstrate whether periodic operation can influence product selectivity for CO2R, which is not only of practical but also of fundamental importance.