ZnO-TiO₂ Binary Compound Core–Shell Nanorods for Selective Sensing of Short-Chain Alcohols

The regularly ordered core–shell nanorods provide an effective transport channel for the adsorption and desorption of the target molecules. However, it remains a great challenge to precisely control the shell thickness of the ordered core–shell nanorods and improve the catalytic activity of their surfaces due to the complexity of the reaction system, especially by enhancing their selectivity to short-chain alcohols. Herein, we propose ZnO/TiO2 core–shell nanorod arrays (NRs) with different shell thicknesses prepared by electron beam evaporation and found that they possess advanced selectivity for short-chain alcohols. The response time of a ZnO/TiO2 core–shell NR with a TiO2 shell of 30 nm to 100 ppm isoamyl alcohol is 17 s. Its response to 100 ppm of isoamyl alcohol is 807, which is approximately 158 times that of the pure ZnO NR. The ZnO/TiO2 NR (30 nm) sensor exhibited excellent selectivity for methanol, ethanol, isopropanol, n-butanol, and isoamyl alcohol. The response to alcohols increased with the increase of the alcohols’ chain length. Its sensing mechanism for short-chain alcohols is explained in terms of adsorption energy, acidity, and electronegativity of H in organic groups by density functional theory in detail. Our results open an alternative route for the design of sensitive materials for the selective detection of short-chain alcohols.