Mechanism of Hydrogen Peroxide Formation by Alternating Current and Direct Current Plasma Jets

In this work, a discharge device is designed to realize the generation of alternative current (ac) and direction current (dc) cold atmospheric plasma (CAP) jet in the same generator for studying the production mechanism of H2O2 induced by plasma in water. The interaction between the plasma jets and deionized water is decomposed into three pathways by using a special reactor system, including electrochemical pathway, gaseous dissolution pathway, and the integrated pathway. Two kinds of ac plasma jets are generated by adjusting the electrode structure of the plasma generator, meanwhile two kinds of dc plasma jets are generated by adjusting the polarity of the discharge electrodes. Stable plasma jets are generated in all four configurations. The aqueous H2O2 as well as its vital precursor hydroxyl radical (OH) produced by the plasma jets is detected. The results show that the producing pathway of aqueous H2O2 depends on the position where the OH recombination reaction takes place during the treatment, and does not depend on whether the plasma is excited by ac or dc electric power.