Room temperature NO2 gas sensor based on porous Co3O4 slices/reduced graphene oxide hybrid

The porous flake-like Co3O4 and Co3O4/graphene hybrids with different graphene contents were prepared through a facile two-step method. The field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) characterizations proved the tight adherence of graphene sheets to the surface of porous Co3O4 slices. Gas sensors based on the as-synthesized products were then fabricated to explore their potential applications. The results indicated that the optimal hybrid exhibited a response of 26.8% to 5 ppm of NO2 at room temperature (RT), which was 2.27 times higher than that of undoped Co3O4 (100 degrees C). The hybrid sensor also showed fast response, excellent selectivity, long-term stability and extremely low detection limit toward NO2 at RT. The significantly enhanced sensing properties to NO2 could be attributed to larger specific surface area, more chemisorbed oxygen species and the coupling effect between Co3O4 and graphene in the hybrid. As we all know, as a typical p-type semiconductor, the gas-sensing properties of Co3O4 toward oxidizing gases including NO2 was rarely reported. We believe that our work could pave the way for the future design of Co3O4-based gas sensors for oxidizing gases detection at low or even room temperature. (C) 2018 Elsevier B.V. All rights reserved.