Field Heterogeneities and Their Impact on Photocatalysis: Combining Optical and Kinetic Monte Carlo Simulations on the Nanoscale,The Journal of Physical Chemistry C

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Field Heterogeneities and Their Impact on Photocatalysis: Combining Optical and Kinetic Monte Carlo Simulations on the Nanoscale
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2020-01-22 , DOI: 10.1021/acs.jpcc.9b11469
Martin Hammerschmidt ₁ , Sandra Döpking ₂ , Sven Burger ₁ , Sebastian Matera ₂

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Gaining insights into the working principles of photocatalysts on an atomic scale is a challenging task. The obviously high complexity of the reaction mechanism involving photoexcited electrons and holes is one reason. Another complicating aspect is that the electromagnetic field, driving photocatalysis, is not homogeneous on a nanoscale level for particle-based catalysts as it is influenced by the particle’s shape and size. We present a simple model, inspired by the CO₂ reduction on titania anatase, which addresses the impact of these heterogeneities on the photocatalytic kinetics by combining kinetic Monte Carlo with electromagnetic wave simulations. We find that average activity and especially efficiency might differ significantly between different particles. Moreover, we find sizable variation of the catalytic activity on a single facet of a nanocrystal. Besides this quantitative heterogeneity, the coverage situation in general changes laterally on this facet, and we observe a concomitant change of the rate-determining steps. This heterogeneity on all levels of photocatalytic activity is masked in experimental studies, where only the spatially averaged activity can be addressed. Microkinetic models based on experimental findings might therefore not represent the true microscopic behavior, and mechanistic conclusion drawn from these needs to be handled with care.

中文翻译：

场异质性及其对光催化的影响：在纳米尺度上结合光学和动力学蒙特卡洛模拟

深入了解原子级光催化剂的工作原理是一项艰巨的任务。涉及光激发电子和空穴的反应机理的明显高复杂性是原因之一。另一个复杂的方面是，驱动光催化的电磁场在纳米尺度上对于基于颗粒的催化剂而言是不均匀的，因为它受颗粒形状和尺寸的影响。我们提出了一个受CO ₂启发的简单模型减少锐钛矿型锐钛矿，通过结合动力学蒙特卡洛法和电磁波模拟解决了这些异质性对光催化动力学的影响。我们发现，不同颗粒之间的平均活性，尤其是效率可能存在显着差异。而且，我们发现在纳米晶体的单面上催化活性的相当大的变化。除了这种数量上的异质性之外，覆盖面的情况通常在该方面横向变化，并且我们观察到速率确定步骤的随之变化。在所有水平的光催化活性中这种异质性在实验研究中被掩盖了，在实验研究中只能解决空间平均活性。因此，基于实验结果的微观动力学模型可能无法代表真正的微观行为，

更新日期：2020-01-23

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