Effect of Crystal Defect on Gas Sensing Properties of Co₃O₄ Nanoparticles

Abstract

Crystal growth-controlled Co 3 O 4 nanoparticles were prepared to examine gas sensing properties. A cube-like, an irregular shaped, and three kinds of raspberry-type structures were observed by morphology analysis. The raspberrytype structures have an expanded lattice volume with a large oxygen deficiency area, and the cube-like structure has a contracted lattice volume as compared to the irregular shaped structure. The raspberry-type structures exhibited a higher sensor signal response than the others. A relationship between sensor properties and crystal defect was investigated, and it was revealed that the gas selectivity to a high dipole moment value of a reducing gas molecule increased with increasing oxygen deficiency area of the Co 3 O 4 nanoparticle. It was considered that the oxygen deficiency area acted as an important reaction site, which can be attributed to the selective reaction of the Co 3 O 4 nanoparticle with gas molecules.

Low-temperature operating ZnO-based NO2 sensors: a review

“…Oxygen vacancies are regarded as reactive oxygen species, and the unpaired electrons present in ZnO can serve as active sites for gas-sensing reactions, which will enhance gas adsorption and dissociation, as well as promote subsequent redox reactions. [64][65][66] Up to now, ZnO with different morphologies have been designed to achieve room-temperature gas-sensitivity through various routes. Different spatial structures lead to different gas diffusion capacities during the adsorption-desorption process of gas molecules.…”

Tin Oxide Nanosheets on Microelectromechanical System Devices for Improved Gas Discrimination

“…In addition, the SnO 2 (101) crystal facet is in a metastable state and easily forms many crystal defects on the surface, as compared to the most stable SnO 2 (110) crystal facet. Crystal defects can predominantly affect the sensing properties . In the case of the SnO 2 nanosheet, the presence of many crystal defects on the surface is most likely due to the rough surface of the SnO 2 nanosheet (as seen in the HR-TEM image, dotted yellow line).…”

Highly Sensitive H2 Sensors Based on Co3O4/PEI‐CNTs at Room Temperature

“…Metal oxide semiconductors in nanostructure have been widely used as the active materials for gas sensing because of their high catalytic activities and improved selectivity from the distinctive structure [7][8][9][10]. Cobalt oxide (Co 3 O 4 ) is a p-type semiconductor and could be potentially employed for supercapacitors, electrochemical devices, and gas sensors due to its excellent electrocatalytic properties, high biocompatibility, and low cost [11][12][13][14][15][16]. A variety of harmful and toxic gases were detected using Co 3 O 4 nanoparticles, such as volatile organic compounds (VOCs), H 2 S, and NH 3 [17][18][19][20].…”