Interface-Confined Cavitation at an MXene/TiO₂ Schottky Heterointerface for Non-Thermal Juice Preservation

Non-thermal food preservation demands catalytic platforms that achieve potent antimicrobial efficacy without compromising heat-labile nutrients. Yet whether a sonocatalyst merely seeds bubble nucleation or actively channels transiently concentrated acoustic energy into chemical work has remained unresolved, and the violent, opaque nature of cavitation further precludes operando observation of catalyst surfaces. Herein, an MXene/TiO₂ Schottky heterointerface is engineered with the aim of localizing cavitation collapse at the catalyst-liquid boundary through three cooperatively acting determinants: a built-in electric field for charge separation, hierarchical surface roughness for energy focusing, and pre-existing oxygen vacancies for dynamic defect modulation. A convergent multi-proxy evidence chain, comprising passive cavitation imaging, single-bubble computational fluid dynamics, chronoamperometry, quasi-in situ spectroscopy, and ab initio molecular dynamics (AIMD), supports a working model of this interface-confined cavitation regime. Under 40 kHz ultrasound without external heating, the interface delivers 3-log inactivation of the tested indicator bacteria (E. coli and S. aureus) at the laboratory scale, while preserving 82% of vitamin C and 88% of total anthocyanin content in juice. This work thus proposes interface-confined cavitation as a transferable design rationale for sonocatalytic interfaces, with operando validation of the active interface as the decisive next step.