(Invited) Redox Chemistry Driven by Atmospheric Pressure Plasma Jet

Abstract

Plasmas may be considered as mixed ionic and electronic conductors. From an electrochemical point of view, a conducting gas presents a wonderful opportunity to explore redox reactions without all the restrictions a solvent medium provides. Identifying a plasma medium suitable to allow electrochemical measurements can be technically challenging, often due to the electrical energy used to create the plasma. However, atmospheric pressure plasma jets (APPJ)1&2 have been shown to be accessible and convenient as laboratory plasma sources. They present a medium that may be considered as an electrode, due to the presence of electrons or as electrolytes, due to their electrical conduction.3 Although its definition is not too important, the presence of free electrons gives an opportunity to drive reduction processes.The interesting aspect of non-thermal plasmas, and the root of their interesting chemistry, is partly due to the imbalance of thermal kinetic energy distribution between the electron and all the other species, neutral or ionized. As a consequence plasma jets are found in routine industrial applications such as etching or cleaning of surfaces for adhesion promotion. Furthermore, there is a growing body of evidence to suggest that APPJ may be used for the treatment of solid tumors. These highly energized electrons can drive redox reactions, as well as other chemical reactions, at solid or liquid can be unexpected. In this presentation I will explore the use of APPJ for reduction of metal oxides under potentiostatic control and material synthesis.4-6 References Ratcliffe, L.V., et al., Surface analysis under ambient conditions using plasma-assisted desorption/ionization mass spectrometry. Analytical Chemistry, 2007. 79(16): p. 6094-6101.Golda, J., et al., Concepts and characteristics of the 'COST Reference Microplasma Jet'. Journal of Physics D-Applied Physics, 2016. 49(8).Rumbach, P.; Bartels, D. M.; Sankaran, R. M.; Go, D. B., The solvation of electrons by an atmospheric-pressure plasma. Nature Communications 2016, 6, 7248.Sener, M. E., Quesada Cabrera, R., Parkin, I.P., Caruana, D. J., Facile formation of black titania films using an atmospheric-pressure plasma jet, Green Chemistry 2022 , 24, 2499-2505.Sener, M. E., Palgrave, R., Quesada Cabrera, R., Caruana, D. J., Patterning of Metal Oxide thin Films using H2/He Atmospheric Pressure Plasma Jet. Green Chemistry 2020, 22, 1406-1413.Sener, M. E.; Caruana, D. J., Modulation of copper(I) oxide reduction/oxidation in atmospheric pressure plasma jet. Electrochemistry Communications 2018, 95, 38-42.