Cobalt-doped ZnAl-LDH nanosheet arrays as recyclable piezo-catalysts for effective activation of peroxymonosulfate to degrade norfloxacin: non-radical pathways and theoretical calculation studies

Peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) are considered promising technologies for the degradation of recalcitrant norfloxacin in wastewater. However, this technology exhibits sluggish carrier transport and slow regeneration of the catalytic center. In this study, cobalt-doped ZnAl-layered double hydroxides (ZnAl-LDH) were synthesized as recoverable piezoelectric catalysts for efficient activation of PMS. The cobalt-doped ZnAl-LDH (0.06 mmol cobalt) demonstrated the most effective degradation performance within 15 min, achieving a degradation efficiency of 91.50% and a rate constant of 0.1644 min−1. The constructed piezoelectric catalytic system was mainly based on a non-radical mechanism, including singlet oxygen (1O2) and electron transport. Notably, the remarkable piezoelectric properties of the catalyst accelerated carrier transport and promoted regeneration of the catalytic active center (Co2+). The remarkable structural stability of the catalyst not only resulted in a significant reduction of Co leaching, but also enabled its successful adaptation to complex aqueous environments. This study provides non-negligible importance for future research on the structure and mechanism of piezoelectric catalysts used for PMS activation.