Facile preparation of cobalt doped ZnO hierarchical structures for enhanced triethylamine gas sensing performance

In this work, the Co doped ZnO (CZO) hierarchical structures were synthesized via hydrothermal approach at 100 °C. The results of characterization illustrated that the products were assembled by large quantities of ultra-thin nanosheets with porous feature, the average crystallite size decreased from 20.27 nm to 16.98 nm with doping, and Co element existed uniformly in the hexagonal wurtzite ZnO lattice in the form of coexisting Co²⁺/Co³⁺ ions and did not appear as secondary phases. Triethylamine (TEA) sensing performance of the CZO sensor were investigated in the concentration range of 2–100 ppm, it possessed ameliorative and potential sensing characteristics, such as enhanced response value (24) doubled as compared to ZnO (12), higher selectivity coefficient (> 2.18), and shorter response and recovery time (7 s/44 s) in the case of 50 ppm TEA, and relatively well repeatability and stability no less than 40 days at 270 °C. The enhanced TEA sensing performance principally put down to the synergistic influence of the catalytic effect of Co element and the increased number of oxygen vacancy and adsorbed oxygen by introducing Co ions.