P-type hollow hexagram Co3O4 detect the acetone at low temperature and mechanism analysis

Abstract

This work successfully synthesized a series of Co3O4 hexagonal particles with controlled morphology via a one-pot hydrothermal method by using NH4F as a structure-directing agent. The amount of NH4F added significantly influenced the products’ hexagonal morphology, which further affected the acetone sensing performance. In particular, the Co3O4 samples with hollow hexagram structures (S-5) different from other samples were obtained with the amount of 42 mmol NH4F. The sensors fabricated with the prepared Co3O4 samples were investigated to figure out the gas sensing performance. Compared to others, the hollow hexagram Co3O4 sensor (S-5) revealed the highest response of 23.32 to 100 ppm acetone at a low working temperature of 150 °C, with a response/recovery time of 48 s/45 s and the lowest limitation of detection was as low as 22 ppb. The excellent sensing performance of the hollow hexagram Co3O4 sample is largely related to the high utilization of exposed active sites and the massive chemical adsorbed oxygen species offered by the specific hollow structure. In addition, the adsorption energies (EAds) between two different cobalt atoms and acetone on the (111) plane of Co3O4 were simulated and calculated by DFT, to further elucidate the mechanism of Co3+ for the ultra-high performance to acetone.