MOF-Derived Tourmaline@ZnO Nanostructure as a High-Response Sensing Material of Gas Sensors toward n-Butanol

Abstract

Herein, in order to efficiently enhance the sensing properties based on zinc oxide (ZnO) sensors toward n-butanol, a series of MOF ZIF-8 (zeolite imidazolate framework-8)-derived Tourmaline@ZnO core–shell nanostructures were prepared with a facile solution mixing method and an after-treatment calcination process, and the gas sensing performances were systematically characterized. The results exhibited that the paucity of tourmaline introduction could significantly improve the gas sensitivity for n-butanol, simultaneously increasing the gas selectivity and reducing the response–recovery times. In particular, the sensor based on 5 wt % Tourmaline@ZnO nanocomposites achieved a superior response value, reaching up to 294.4 for 100 ppm n-butanol at 320 °C. Through the integrated testing and analyses of BET, XPS, PL, and UV, it has been confirmed that the introduction of tourmaline can not only enlarge the specific surface area and enrich the surface defects of the ZnO matrix, but its unique spontaneous polarization electric field can also reduce the recombination rate of electron–hole pair efficiency, promoting the efficiency of electron transport and accelerating the gas sensing process ultimately. The enhancement mechanism of the nanostructured Tourmaline@ZnO core–shell gas sensing material was also elucidated from the perspective of the energy band theory at length.