Z-scheme plasma-catalysis using Ru-doped CeO₂/Bi₂O₃ for efficient GenX degradation via oxygen vacancy engineering

Herein, GenX, a substitution chemical for perfluorooctanoic acid (PFOA) was degraded using argon (Ar) jet plasma combined with ruthenium doped cerium oxide/bismuth oxide composite (CeO₂/Bi₂O₃, CBO). As a result, GenX removal using 0.1% Ru-doped CBO [Ru (0.1%)-CBO] in plasma system achieved up to 74% degradation performance in 30 min, 1.7-folded higher than that of sole plasma. The GenX removal kinetic rates showed strong correlations with the concentration of O_V and the (1 1 1) facet, identifying them as key factors in GenX removal. The contribution analysis of the reactive species revealed that hydroxyl radical (•OH) and singlet oxygen (¹O₂) were important for the GenX degradation in both plasma and plasma-catalysis. In-situ X-ray photoelectron spectroscopy (XPS) and surface-enhanced-Raman spectroscopy (SERS) analyses revealed a clear electron transfer pathway of Ru (0.1%)-CBO from CeO₂ to Bi₂O₃ and finally to RuO₂, confirming a Z-scheme mechanism facilitated by RuO₂ acting as an electron sink. The combination of argon jet plasma with Ru (0.1%)-CBO significantly enhanced energy efficiency, reducing the electrical energy per order (E_EO) from 295.8 to 149.7 kWh m^-3 for GenX degradation. Overall, Ru (0.1%)-CBO demonstrates high catalytic stability and energy efficiency, offering a promising strategy for PFAS remediation.