Porous cobalt oxide nanowires: Notable improved gas sensing performances

Abstract

The porous Co 3 O 4 nanowires have been successfully synthesized via modified template method. A possible growth mechanism governing the formation of such 1D nanowires is proposed. The as-prepared products have been characterized by X-ray Powder Diffraction (XRD), Extended X-ray Absorption Fine-structure (EXAFS), High-resolution Transmission Electron Microscopy (HRTEM) and N 2 adsorption/desorption analysis. Our systematic studies have revealed that the porous Co 3 O 4 nanowires show excellent gas sensing performances, which demonstrate the potential application of the 1D nanostructured Co 3 O 4 in the detection of the ethanol gas as a sensor material. The improved performances are owing to its large specific surface area and porous morphology. [4][5][6][7]. In particular, the thermal conversion of cobalt nitrate hexahydrate in silica templates to nanowires has proven to be promising. Thus, it is worthwhile to study the gas-sensing characteristics of one-dimensional (1D) Co 3 O 4 nanowires. The extended X-ray absorption fine-structure (EXAFS) technique is a powerful tool for probing the local atomic structures because of its element specificity and independence of the long-range order of materials [8]. The EXAFS spectra have provided many quantitative structural parameters such as interatomic distance, co-ordination number, and Debye-Waller factor [9]. EXAFS study is an indispensable method for investigate the local structure in the interior and at the surface, as well as bonding information of a variety of solid-state materials [10]. Herein, we report on a template synthesis leading to porous Co 3 O 4 nanowires using SBA-15 as hard templates. Moreover, the local structure in the interior and at the surface of the Co 3 O 4 nanowires and the bulk Co 3 O 4 were studied by EXAFS. The gas-sensing application of the as-prepared porous Co 3 O 4 nanowires was systematically investigated in detail.

General fabrication and enhanced VOC gas-sensing properties of hierarchically porous metal oxides

“…[9][10][11] In order to obtain greater gas-sensing properties, like high sensitivity, fast response and rapid recovery, most research focused on improving the gas-sensing properties of metal oxide materials includes three aspects, namely, a nanostructure, a hierarchically porous structure, and noble-metal surface modication. [12][13][14] Through the above three measures, the lm will display a higher sensitivity, due to its very large specic surface area, which provides more gas channels and improves the utilization of the material. In addition, a hierarchically porous structure can offer more surface active sites that allow the material to contact the target gas directly, which not only increases physical and chemical adsorption, but also greatly shortens the response and recovery time.…”