Quaternary ammonium salt-tailored MoS2 with expanded interlayer spacing for enhanced piezo-photocatalytic degradation of tetracycline

TBAB-assisted MoS 2 with expanded interlayer spacing via molecular insertion. • TBAB regulates MoS 2 into open few-layer nanoflower structure. • Enhanced piezo-photocatalytic degradation of tetracycline (97.8%, 60 min). • ·O 2 – identified as dominant reactive species in degradation. • Enhanced charge separation via Mo 5+ /Mo 6+ and N-related states. MoS 2 is a promising piezo-photocatalyst for pollutant degradation, but nanosheet restacking, limited active-site exposure and fast charge recombination restrict its performance. Quaternary ammonium salts can regulate layered MoS 2 through interfacial adsorption and steric effects, yet the role of molecular configuration remains unclear. Here, TMAB, TBAB, DTAB and CTAB were compared to examine cation-size and alkyl-chain effects. The interlayer spacing increased from 6.28 Å to 6.65, 10.16, 10.27 and 10.22 Å, respectively. M−TBAB formed an open few-layer flower-like structure due to strong TBAB-MoS 2 interaction and steric hindrance. High-valence Mo species and N-containing surface components favored interfacial charge transfer. Under light alone, M−TBAB degraded 25.2% of tetracycline within 60 min versus 14.3% for pristine 2H-MoS 2 , with k app  = 0.0048 min −1 , 1.71 times that of pristine 2H-MoS 2 . Under coupled light/ultrasound, degradation reached 97.8% with k app  = 0.0621 min −1 , 3.09 times that of pristine 2H-MoS 2 . The improved activity mainly arises from the expanded interlayer spacing, stronger piezoelectric response, improved charge separation, and surface electron redistribution. Radical trapping experiments further indicate that ·O 2 – is the dominant reactive species. Distinct from our previous sulfur-vacancy engineering of MoS 2 , this work demonstrates organic molecular configuration as an effective strategy for regulating the layered structure and interfacial properties of MoS 2 toward enhanced piezo-photocatalysis. TBAB-modified MoS 2 exhibits expanded interlayer spacing and enhanced piezo-photocatalytic performance toward efficient tetracycline degradation. Download: Download high-res image (212KB) Download: Download full-size image