High response ZnO gas sensor derived from Tb@Zn-MOFs to acetic acid under UV excitation

Abstract

As an n-type metal oxide semiconductor with a wide band gap (3.37 eV), ZnO has been widely used as gas sensors, but pure ZnO gas sensors suffer from low sensitivity. In this work, Zn-metal organic frameworks (Zn-MOFs) were synthesized by introducing H3BTC and H2ABDC as organic ligands, and then the Zn-MOFs were combined with Tb and calcined at 530 ℃ to obtain the derived oxides named as Tb@ZnO-1 and Tb@ZnO-2, respectively, in order to improve the gas sensitivity. Meanwhile, the microstructures and gas sensing properties of the two MOFs and their derivatives were characterized. Interestingly, the Zn-ABDC MOFs were observed as plush spherical microspheres assembled from nanowires, more possibly favorable for gas adsorption. In fact, prominent oxygen defects and chemisorbed oxygen content were found in the derivative Tb@ZnO-2. As a result, it exhibited good gas-sensitive properties and selectivity towards acetic acid, with a high response value of 47.30 at 240 ℃ for 100 ppm acetic acid gas and a very short response time (1 s), and the response value increased to 77.80 under UV excitation. The gas-sensitive mechanism and UV excitation mechanism are discussed.