Hydrogen peroxide generation by atmospheric pressure discharge in contact with aqueous solutions

In this study, we investigate a pulsed discharge plasma generated above distilled water with initial pH values ranging from 2–13 approach for the synthesis of hydrogen peroxide (H2O2). Non-thermal plasma, produced using argon as the working gas, generates a diverse range of reactive oxygen species, including hydroxyl radicals (•OH), superoxide anions (O2−•), and atomic oxygen, which drive the in situ formation of H2O2 in the liquid phase. We systematically examine the influence of key operational parameters such as input voltage, frequency, discharge duration, and pH of the aqueous environment on both H2O2 production and energy yield efficiency. Experimental results demonstrate a clear correlation between energy input and H2O2 generation: the H2O2 concentration increased from 0.69 to 1.43 mM as the voltage was raised from 4 to 8 kV at a constant frequency of 500 Hz. Furthermore, the pH of the solution significantly impacted the plasma-induced chemical pathways, with H2O2 concentrations rising from 1.3 to 3.3 mM after 10 min as the pH decreased from 13 to 2. The highest production rate of 1.03 × 10−1 g/h was observed at pH 2, accompanied by an energy yield of 2.11 g/kWh. This work presents an initial investigation into enhancing the production efficiency of plasma-generated reactive species in aqueous environments, particularly H2O2. Our results demonstrate energy yield values that are 2–10 times higher than previously reported studies. These findings highlight the potential of plasma–liquid interaction for environmentally friendly and tunable H2O2 generation under ambient conditions.