Graph-based approach to catalytic effects in plasma-exposed liquids

Cold atmospheric plasmas (CAPs) have been widely studied in the fields of biomedicine or agriculture. In these applications, plasma- Cold atmospheric plasmas (CAPs) have been widely studied in the fields of biomedicine or agriculture. In these applications, plasma-activated liquids/solutions are gaining increasing attention because they can produce abundant reactive species. Because there are various combinations of the CAP source and the type of solution used, we still have some challenges to reach comprehensive understanding of the nature of CAP-induced chemistry in liquids/solutions. This study propose mathematical/numerical approaches to investigate the CAP-liquid interaction. The complex network analysis based on the graph-theory, one of the information mathematics, enable us to reveal the hidden feature of liquid-phase chemistry through the visualization and centrality-based identification of the reacting network structure [1, 2]. Particular emphasis will be placed on examining the catalytic effect. Numerical simulation will quantify the influence of CAP irradiation on the chemistry in liquids. A one-dimensional reaction-diffusion model with hundreds of reaction processes can reveal how various plasma species permeate into the liquid and what reactions are triggered. In particular, the interaction between plasma-induced reactive oxygen / nitrogen species and solutions containing various components (depending on the application) is extremely complicated and is a subject to be challenged. [1] T. Murakami and O. Sakai, Plasma Sources Sci. Technol. 29, 115018 (2020). [2] O. Sakai, S. Kawaguchi and T. Murakami, Jpn. J. Appl. Phys. 61 (2022) (in Press).