Enhanced NO2 sensing performance based on Au nanocluster functionalized Co3O4 nanospheres

P-type spinel cobalt oxide (Co3O4) is widely used in the design and manufacture of chemical-resistant gas sensors due to its large specific surface area and high oxygen content. However, most current p-type Co3O4-based sensors exhibit weaknesses in gas susceptibility and high working temperature towards NO2 detection. In this work, we report a highly sensitive NO2 gas sensor based on Au-functionalized Co3O4 nanospheres. The Co3O4 nanospheres were fabricated by a hydrothermal method and then acted as a precursor for loading Au nanoclusters using glutathione (GSH) as a reducing reagent to obtain the composite material. The characterization results demonstrate that the introduction of Au doping significantly improved the chemical bonding state and microstructure of the composite material's surface. Compared to a pure Co3O4 sensor, the Au/Co3O4 nanohybrid with a weight percentage of 0.25% exhibited the highest response of 23.6 towards 20 ppm NO2 at 120 degree celsius. Further investigation indicates that it also has good humidity resistance, preferable repeatablity and adequate linearity. The gas sensing performance can be predominantly attributed to the spherical structure of the composite materials, modulation of the nano-Schottky junction, and the special chemical properties of Au nanoclusters.

Automated summary

A highly sensitive NO2 gas sensor based on Au-functionalized Co3O4 nanospheres is reported in this work. The Co3O4 nanospheres were fabricated by a hydrothermal method and loaded with Au nanoclusters using glutathione as a reducing reagent. The introduction of Au doping significantly improved the chemical bonding state and microstructure of the composite material's surface. The Au/Co3O4 nanohybrid exhibited a high response towards NO2 at a specific temperature, as well as good humidity resistance, repeatability, and linearity.