The advances of Co3O4 as gas sensing materials: A review

As a p-type semiconductive material, Co3O4 has been widely studied as gas sensor materials, in addition to energy storage, catalyst and magnetic semiconductor. The gas sensors prepared using Co3O4 and its composites were reviewed in this work. Investigation has indicated that the gas sensing performances of Co3O4 micro-/nanostructures are strongly related to the surface area, porous nature and morphologies. Thus, the gas sensing properties of Co3O4 micro-/nanostructures will change with the tuned configurations. Hierarchically porous structures of Co3O4 usually exhibit a high response and low operating temperature to detect gases. In this review, attention is also focused on Co3O4-based composites, including Co3O4/inorganic metal oxides, Co3O4/carbon nanomaterials, Co3O4/polymers and Co3O4/noble metals, due to their unique effects on the final gas sensing application. The Co3O4 composites generally show higher gas response than single component due to the catalytic action or synergetic effects between the components. This paper has summarized an overview of the literature on gas sensing of Co3O4 and suggested potential directions for future progress.