CO and NO2 Selective Monitoring by ZnO-Based Sensors

ZnO nanomaterials with different shapes were synthesized, characterized
and tested in the selective monitoring of low concentration of CO and
NO2 in air. ZnO nanoparticles (NPs) and nanofibers (NFs) were
synthesized by a modified sol-gel method in supercritical conditions and
electrospinning technique, respectively. CO and NO2 sensing tests have
demonstrated that the annealing temperature and shape of zinc oxide
nanomaterials are the key factors in modulating the electrical and
sensing properties. Specifically, ZnO NPs annealed at high temperature
(700 degrees C) have been found sensitive to CO, while they displayed
negligible response to NO2. The opposite behavior has been registered
for the one-dimensional ZnO NFs annealed at medium temperature (400
degrees C). Due to their adaptable sensitivity/selectivity
characteristics, the developed sensors show promising applications in
dual air quality control systems for closed ambient such as automotive
cabin, parking garage and tunnels.