Eu-doped Tourmaline@MOF-ZnO core-shell nanocomposites: Enabling UV-activated room-temperature and ppb-level n-butanol sensing

Achieving gas sensors that exhibit excellent sensitivity, selectivity, and rapid response to volatile organic compounds (VOCs) is critically important for effective environmental monitoring applications. In this research, a novel Eu-doped Tourmaline @MOF-ZnO core-shell nanocomposite was designed and fabricated, integrating a MOF-derived porous ZnO shell, a spontaneously polarized tourmaline core, and rare-earth Eu doping. The gas sensing properties of the sensors were systematically investigated across three different test scenarios: (i) at high temperature in the dark, (ii) at high temperature with UV enhancement, and (iii) at room temperature with UV activation. The optimized 0.08 wt% Eu-5 wt% TML-ZnO sensor achieved an exceptional response of 536 to 100 ppm n-butanol at room temperature under UV activation. The response value exceeds that of the pristine MOF-ZnO sensor by a factor of 14.78. Furthermore, the sensor exhibited rapid response/recovery times (39 s and 23 s, respectively), outstanding selectivity and long-term stability, superior detection capability for ultra-low gas concentrations (LOD = 23.35 ppb). This study pioneers a synergistic UV-activated rare-earth doping strategy for TML@MOF-ZnO core-shell nanostructures, enabling room-temperature ppb-level VOCs sensing.