Reduced graphene oxide (rGO) encapsulated Co3O4 composite nanofibers for highly selective ammonia sensors

The reduced graphene oxide (rGO) encapsulated Co3O4 nanocrystals were fabricated by using the electrospinning technology. The sample shows nanofiber morphology and the Co3O4 nanocrystals were wrapped by rGO thin layers. The as-electrospun rGO-Co3O4 nanofibers based chemoresistive sensor exhibited a p-type semiconductor behavior in ambient conditions and showed an excellent sensitivity with a fast response and recovery to different concentrations of ammonia from 5 to 100 ppm at room temperature. The sensor displays selectivity to several potential interferrents such as methanol, ethanol, formaldehyde, acetone, benzene, and methylbenzene. It may be attributed to the unique hierarchical wrapping microstructure and the selective NH3 adsorption at both the wrapping layer of rGO and the polarized C-Co3+ covalent centers within the nanofibers. (C) 2015 Elsevier B.V. All rights reserved.