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

Abstract

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 °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 O2 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.

Activated Single‐Phase Ti4O7 Nanosheets with Efficient Use of Precious Metal for Inspired Oxygen Reduction Reaction

“…The highest proportion of O 2 ads in O1s spectra area is the VI−Pt/Ti 4 O 7 (57 %), while the value decreases to 33 and 9 % when the induced light is UV and no light irradiation (Figure 3a–c, Table S2). The spectra of Ti 4 O 7 only shows two main peaks located at around 530.3 and 531.4 eV (Figure 3d) [20,24] . It could be deduced that the insertion of precious metal activates the Pt/Ti 4 O 7 catalysts to make it possess strong adsorption capacity for O 2 , which is mutually confirmed with the previous O element mapping results.…”

“…The spectra of Ti 4 O 7 only shows two main peaks located at around 530.3 and 531.4 eV (Figure 3d). [20,24] It could be deduced that the insertion of precious metal activates the Pt/Ti S2), which suggests the Pt 2 + sites is great significance to the O 2 ads capacity. The Pt 4f 7/2 XPS spectrum of VIÀ Pt/Ti 4 O 7 has peaks at 71.48, 72.22, and 74.24 eV, which are attributed to Pt 0 4f 7/2 , Pt 2 + 4f 7/2 , and Pt 4 + 4f 7/2 , respectively (Figure 3e).…”

“…[14][15][16] For carbon-free electrodes, metal oxides-based catalyst is a hotspot in the research field in recent years, and exhibits outstanding performance (Pt/CeO 2 , Pt/W 18 O 49 , Pt/V 2 O 5 …). [17][18][19][20][21] However, the conductivity and corrosivity of the metal oxides are crucial obstacles to their application and promotion. TiO 2 is an attractive candidate substrate due to its corrosion resistance, electrochemical stability, environmental friendliness.…”

“…In commercial Pt/C catalysts, the substrate C is gradually etched and dissolved during the long‐term recycling, leading to the dissolution and poisoning of Pt, and further decreasing the battery capacity and service life [14–16] . For carbon‐free electrodes, metal oxides‐based catalyst is a hotspot in the research field in recent years, and exhibits outstanding performance (Pt/CeO 2 , Pt/W 18 O 49 , Pt/V 2 O 5 …) [17–21] . However, the conductivity and corrosivity of the metal oxides are crucial obstacles to their application and promotion.…”

Effect of Pr/Zn on the anti-humidity and acetone-sensing properties of Co3O4 prepared by electrospray

“…However, under high humidity conditions greater than 80%, the acetone responses of the sensors show a drop of more than 15%, and some even drop by 66.7%. [16][17][18][27][28][29] The sensor of Pr 10 Zn 40 Co 50 in this work shows good agreement in low and high humidity, and the relative deviation is much smaller than the reported.…”