Photodeposition of Pt Nanoparticles on Co3O4 Nanocubes for Detection of Acetone at Part-Per-Billion Levels

Noble-metal-decorated metal oxide sensors have shown promising gas-sensing properties. However, the optimal dispersion of metal particles on a semiconductor is still challenging for most sensing materials. In this study, Co3O4 nanocubes (NCs) and Pt-supported Co3O4 NCs were prepared as sensing materials for acetone gas detection. Transmission electron microscopy and X-ray diffraction were used to examine the structure and exposed facets of Co3O4 NCs. As a result, the Co3O4 NCs were identified as the single-crystalline phase of spinel Co3O4, and each surface exposed the {100} plane. To examine the cocatalytic effect of Pt combined with Co3O4 NCs on the sensing performance, Pt nanoparticles were photodeposited on Co3O4 (Pt-Co3O4 NCs). The Pt-Co3O4 NC-based sensor provided a higher p-type response than the Co3O4 NC sensor in the detection of 500 ppb acetone at 200 degrees C, with the highest response of 3.1 (R-g/R-a). The enhanced performance of the Pt-Co3O4 NCs is caused by the exposed {100} planes of Co3O4, in addition to the loaded Pt nanoparticles. The sensor with Co3O4 NCs has a larger neck diameter and hole accumulation layer at the interface than that with Co3O4 nanospheres and thus provides a wide channel for charge carriers, resulting in better gas-sensing responses and high selectivity toward acetone over other volatile compounds. Moreover, the Pt nanoparticles stimulate O-2 dissociation on the Co3O4 surface, thus increasing the concentration of chemisorbed oxygen species by the spillover effect. Thus, the incorporation of Pt with Co3O4 NCs promotes the sensitivity of the material in the detection of acetone gas and also enhances the selectivity. This study highlights the possibility of the rapid deposition of metal nanoparticles for the improvement of gas sensors.

Automated summary

Noble-metal-decorated metal oxide sensors have shown promising gas-sensing properties, but the optimal dispersion of metal particles on a semiconductor remains challenging. In this study, Co3O4 nanocubes and Pt-supported Co3O4 nanocubes were prepared for acetone gas detection. The Pt-Co3O4 nanocube-based sensor demonstrated higher p-type response and enhanced selectivity toward acetone due to the exposed {100} planes of Co3O4 and incorporated Pt nanoparticles.