Plasma parameters and the reduction potential at a plasma–liquid interface
Plasma parameters and the reduction potential at a plasma–liquid interface
复制标题
等离子体参数和等离子体-液体界面处的还原电位
DOI：
10.1039/d2cp00203e
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发表时间：
2022
影响因子：
3.3
通讯作者：
Thimsen, Elijah
中科院分区：
文献类型：
--
作者：
Oldham, Trey;Yatom, Shurik;Thimsen, Elijah
与液体接触的非热等离子体已被证明会产生各种能够在电化学活性等离子体-液体界面引发还原-氧化（氧化还原）反应的活性物质。在传统的电化学电池中，选择性氧化还原化学是通过外部电路施加偏压来控制固体电极-电解质界面的还原电位来实现的。在等离子体-液体系统的情况下，尚未明确确定调节界面附近还原电位的类似方法。当被视为浮动表面时，液体预计将采用净负电荷来平衡热电子和相对冷的正离子的通量。假设等离子体-液体界面附近的还原电位与浮动电位成正比，如果等离子体参数已知，则可以使用分析模型来近似浮动电位。在此，我们提出了一个将惰性气体等离子体射流的电子密度和电子温度与等离子体-液体界面附近的还原电位相关联的框架。通过激光汤姆逊散射获得与水溶液接触的氩大气等离子体射流的等离子体参数。使用相同的参比电极测量等离子体-液体界面和本体溶液之间的电位差来确定还原电位。有趣的是，发现等离子体-液体界面附近测量的还原电位与使用汤姆森散射实验获得的等离子体参数确定的模型预测值非常一致。
Nonthermal plasmas in contact with liquids have been shown to generate a variety of reactive species capable of initiating reduction–oxidation (redox) reactions at the electrochemically active plasma–liquid interface. In conventional electrochemical cells, selective redox chemistry is achieved by controlling the reduction potential at the solid electrode–electrolyte interface by applying a bias via an external circuit. In the case of plasma–liquid systems, an analogous means of tuning the reduction potential near the interface has not clearly been identified. When treated as a floating surface, the liquid is expected to adopt a net negative charge to balance the flux of hot electrons and relatively cold positive ions. The reduction potential near the plasma–liquid interface is hypothesized to be proportional to the floating potential, which can be approximated using an analytical model provided the plasma parameters are known. Herein, we present a framework for correlating the electron density and electron temperature of a noble gas plasma jet to the reduction potential near the plasma–liquid interface. The plasma parameters were acquired for an argon atmospheric plasma jet in contact with an aqueous solution by means of laser Thomson scattering. The reduction potential was determined using identical reference electrodes to measure the potential difference between the plasma–liquid interface and bulk solution. Interestingly, the measured reduction potentials near the plasma–liquid interface were found to be in good agreement with the model-predicted values determined using the plasma parameters obtained from the Thomson scattering experiments.