Significantly enhanced piezo-photocatalytic in-situ H2O2 generation and activation for efficient antibiotic degradation by g-C3N4/NH2-MIL-101(Fe) heterojunction

Abstract

This study demonstrates the synergistic effect of piezocatalysis and photocatalysis can effectively promote the generation and in-situ activation of hydrogen peroxide (H₂O₂) and enhance the degradation performance of antibiotics. A novel g-C₃N₄/NH₂-MIL-101(Fe) (g-C₃N₄/NMOF) Z-scheme heterojunction was prepared via solvothermal approach. The piezoelectricity of g-C₃N₄/NMOF improves the separation efficiency and lifetime of photogenerated carriers, which is beneficial to the generation of H₂O₂ and degradation of ciprofloxacin (CIP) in piezo-photocatalytic system. Under piezo-photocatalytic progress, g-C₃N₄/NMOF achieves 0.1102 mM/h H₂O₂ yield in pure water, which is 20.6 times and 2.96 times higher than g-C₃N₄/NMOF in piezocatalysis and photocatalysis progresses, respectively. Mechanistic studies reveal that the ·O₂^- is the main intermediate product of H₂O₂, and the generation of H₂O₂ occurs through a two-step one-electron pathway (O₂ → ·O₂^- → H₂O₂). Moreover, g-C₃N₄/NMOF with abundant Fe²⁺ could directly activate H₂O₂ to generate hydroxyl radicals (·OH), forming an in-situ Fenton system and significantly accelerating CIP degradation. The degradation efficiency of CIP reaches 89.87 % within 60 min under piezo-photocatalytic condition, which is 3.25 and 2.54 folds higher than that alone condition. The piezo-photocatalytic H₂O₂ generation and in-situ Fenton mechanism of co-utilizing solar and mechanical energy by g-C₃N₄/NMOF may have potential in applications for cost-effective environmental remediation.