Center for Electrochemical Sciences (CES), Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstr. 150, D-44780 Bochum, Germany.
Faraday Discuss. 2019 Jul 4;215(0):39-53. doi: 10.1039/c8fd00168e.
Redox-active films are advantageous matrices for the immobilization of photosynthetic proteins, due to their ability to mediate electron transfer as well as to achieve high catalyst loading on an electrode for efficient generation of electricity or solar fuels. A general challenge arises from various charge recombination pathways along the light-induced electron transfer chain from the electrode to the charge carriers for electricity production or to the final electron acceptors for solar fuel formation. Experimental methods based on current measurement or product quantification are often unable to discern between the contributions from the photocatalytic process and the detrimental effect of the short-circuiting reactions. Here we report on a general electrochemical model of the reaction-diffusion processes to identify and quantify the "bottlenecks" present in the fuel or current generation. The model is able to predict photocurrent-time curves including deconvolution of the recombination contributions, and to visualize the corresponding time dependent concentration profiles of the product. Dimensionless groups are developed for straightforward identification of the limiting processes. The importance of the model for quantitative understanding of biophotoelectrochemical processes is highlighted with an example of simulation results predicting the effect of the diffusion coefficient of the charge carrier on photocurrent generation for different charge recombination kinetics.
氧化还原活性膜有利于固定光合蛋白，因为它们能够介导电子转移，并且可以在电极上实现高催化剂负载，从而有效地产生电能或太阳能燃料。一个普遍的挑战来自于从电极到用于发电的载流子或用于太阳能燃料形成的最终电子受体的光诱导电子转移链上的各种电荷复合途径。基于电流测量或产物定量的实验方法通常无法区分光催化过程的贡献和短路反应的有害影响。在这里，我们报告了一个反应-扩散过程的通用电化学模型，以确定和量化在燃料或电流产生中存在的“瓶颈”。该模型能够预测包括复合贡献的解卷积的光电流时间曲线，并可视化相应的产物的时变浓度分布。无量纲组可用于直接识别限制过程。通过模拟结果示例说明了该模型对于定量理解生物光电化学过程的重要性，该示例预测了不同电荷复合动力学下载流子扩散系数对光电流产生的影响。
