Plasma catalyzed hydrogen peroxide synthesis in an H-type electrochemical cell

Hydrogen peroxide (H2O2) is a versatile green oxidant widely used in environmental remediation, disinfection, and chemical processing. Plasma electrochemical synthesis offers a catalyst-free and decentralized route for on-site H2O2 production directly from water under ambient conditions. In this study, H2O2 generation is investigated in a double-layer H-type plasma electrochemical reactor, with systematic evaluation of discharge current, solution flow rate, temperature, and working gas composition. The H2O2 concentration increases linearly with increasing discharge current, while competing plasma reactions caused limited electron utilization efficiency. Lower solution flow rates favored higher product accumulation, while elevated temperatures enhanced decomposition under circulation conditions. Gas composition plays a decisive role: Ar plasma produced higher H2O2 yields than O2 or N2, whereas air significantly suppressed H2O2 formation due to nitrite-mediated consumption pathways. An optimized Ar/O2 mixture (54/6 sccm) enables enhanced performance, achieving a maximum H2O2 concentration of 120 mM after 4 h plasma operation. Although this represents significant progress, a substantial gap remains toward practically usable H2O2 concentrations, highlighting the need for further reactor and energy-efficiency optimization.