Neck-connected ZnO films derived from core-shell zeolitic imidazolate framework-8 (ZIF-8)@ZnO for highly sensitive ethanol gas sensors

Based on the neck-controlled conduction model of chemiresistive gas sensors, construction of neck-controlled conduction networks in metal oxide films is an efficient method to improve their sensitivity. In this work, we develop a facile route to prepare the neck-connected ZnO (NC-ZnO) films with controllable diameters of the necked part by the sintering of core-shell zeolitic imidazolate framework-8 (ZIF-8)@ZnO films. In order to certify the enhancement of sensitivity by construction of neck-controlled conduction networks, their gas sensing properties towards ethanol are systematically investigated. The results demonstrate that the sensitivity of the optimal NC-ZnO film is dramatically improved, and the response value is about 6-times higher than that of ZnO film, reaching up to 124 (Ig/Ia) towards 50 ppm of ethanol. The results meet our expectation and are in conformity with the neck-controlled conduction model, which further indicates the developed approach in this work is expected to open up a new strategy for the preparation of neck-connected metal oxide films.