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 118–50 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.