Preparation of Nanopore-Containing Metal Oxide Particles and Their Gas Sensing Characteristics

Abstract

We reported the successful formation of nanopores within core-shell type metal oxide particles using the shell layer as a template. Using the polyol method, core-shell type metal oxide particles such as cerium oxide, zinc oxide, and cobalt oxide with primary particles of ~10 nm and secondary particle sizes between 20 and 300 nm were prepared, where the polymer shells comprised 10-20 wt% of the total mass. These particles were easily dispersed in water and organic solvents without the use of dispersants. In addition, the core-shell type metal oxide particles were composed of an agglomeration of several tens of nanometer-sized core-shell primary particles, with sintering at 400 °C generating the desired nanopore-containing metal oxide particles. It was reported that in the SnO2 gas sensor for H2S sensing, nanopore manipulation in the sensor response layer leads to an increased response and selectivity toward H2S compared to the smaller and more reactive hydrogen gas. We therefore expected that an increase in the specific surface area of sensing films through the formation of nanopores in the secondary particles could result in additional reaction sites to lead to a higher gas responsiveness. Indeed, this was assumed to account for the high selectivities of high specific surface area cobalt nanofiber and nanosheet gas sensors toward acetone gas and ethanol gas. In this work, metal oxide particles with nanopores were prepared by a polyol method and sintering. The gas sensor characteristics of the particles with nanopores were compared with those of the particles without nanopores, and the effectiveness of 3D-nanostructure for gas sensing was also examined.Figure. Schematic representation of the strategy used to prepare the 3D nanostructure of metal oxide particles with nanopores. Figure 1