Enhanced acetic acid detection for Tb2O3 @MOF-derived ZnO at room temperature

As an n-type metallic oxide semiconductor with a wide bandgap of 3.37 eV, ZnO suffers from low sensitivity for gas sensor application. In order to improve the gas sensitivity, Zn-metal-organic frameworks (MOFs) were synthesized by introducing organic ligands of H2BDC/H2NDC via DMF-C2H6O2 binary solvothermal method, and then the MOFs were integrated with Tb3+. After calcination at 450 degrees C, Tb@Zn-BDC/Tb@Zn-NDC derivate, labeled as Tb2O3 @ZnO-1/Tb2O3 @ZnO-2, were obtained. The MOFs or derivates were characterized by various techniques. Interestingly, Zn-NDC MOFs were observed to be assembled by loose bundles with a rough surface and Tb@Zn-NDC MOF maintained the morphology of loose bundles with dispersed Tb2O3 nanoparticles. The Tb2O3 @ZnO-2 were composed of granular Tb2O3 and ZnO nanorods, where p-n heterojunction is formed at the contact interfaces, exhibiting the best sensitivity of 13.26-100 ppm acetic acid at 20 degrees C. In particular, the sensitivity increased up to 41.57 and the lowest detection limit was only 500 ppb under UV light excitation. The enhanced sensing performance to acetic acid is attributed to the mesoporous structure of MOF derivatives, formation of p-n heterostructures and UV light irradiation.