MOF-derived La-doped ZnO Dodecahedron Nanostructures for Efficient Detection of NO2 Gas

Abstract

NO₂ is a toxic gas that poses a significant threat to the environment and human health. In this work, we studied the ultra-high NO₂ sensitivity of lanthanum (La)-doped ZnO porous nanocages. La doping into ZnO via a simple one-step co-precipitation MOF encapsulation-calcination route resulted in a significant improvement in NO₂ sensing performance. This study focused on doping ZnO with 2%, 4%, and 8% molar ratios of lanthanide sources. It was revealed that 2% La-doped ZnO was the best possible parameter for NO₂ gas sensitization. The La-doped ZnO sensor outperforms the pure MOF-derived ZnO sensor with a high response of 118 to 50 ppm NO₂, short response time of 28 seconds, and a detection limit of 5.68 ppb. The material exhibits good reproducibility and some humidity resistance and has good selectivity for NO₂. The excellent NO₂ sensitivity can be attributed to the nanoporous structure providing abundant adsorption sites and the synergistic effect generated by the formation of a heterojunction between La-doped lanthanum oxide and zinc oxide. These findings can be generalized to the design of porous doped ZnO for high-performance gas sensors and other applications.