Fabrication of SnO₂–SnO nanocomposites with p–n heterojunctions for the low-temperature sensing of NO₂ gas

Abstract

In this report, the fabrication of a novel SnO2-SnO nanostructure with p-n heterojunctions has been achieved through a facile one-pot and low-cost hydrothermal process. The structure and properties of the nanocomposite were analyzed with X-ray techniques and electron microscopy. HRTEM characterization showed that the p-n heterojunctions were formed with small n-type SnO2 nanocrystals dispersed on the surface of large p-type SnO crystals. Compared to the single SnO2-based material, a gas sensor fabricated from the SnO2-SnO composite exhibited an enhanced sensing performance for NO2 gas detection, with a limit of detection and sensitivity of 0.1 ppm and 0.26 ppm(-1), respectively, at a relatively low operating temperature (50 °C). Moreover, the p-n heterojunctions exhibited high sensing selectivity for NO2. Such a high sensing sensitivity and a low operating temperature make the SnO2-SnO p-n nanomaterial a promising gas sensor for practical NO2 gas detection. The improved sensing response characteristics of the hybrid material could be attributed to the p-n junctions formed through the in situ growth of SnO2 nanocrystals on SnO nanoplates. The present study is helpful for the design of novel gas sensing materials and the development of NO2 gas sensors.

Influence of fluorine doping on the microstructure, optical and electrical properties of SnO2 nanoparticles

“…The direct band gap is determined using this equation when the straight portion of the (αhν) 2 against hν plot is extrapolated to intersect the energy axis at α = 0. Figure 5 shows the plots of (αhν) 2 versus photon energy hν for FTO nanoparticles with [38,39]. The band gap energies of the SnO 2 materials show a decrease with the increase of doping concentration (Fig.…”

Hierarchical SnO2 nanosheets@SiC nanofibers for enhanced photocatalytic water splitting

“…The grain size of the crystallize SnO 2 is calculated to be 10 nm, according to the Scherrer formula. The formation mechanism of SnO 2 can be attributed to the following sections . First, the urea is hydrolyzed to ammonia and carbon dioxide, and then and are produced from NH 3 and CO 2 , respectively (Equation ).…”

“…The formation mechanism of SnO 2 can be attributed to the following sections. [23][24][25] First, the urea is hydrolyzed to ammonia and carbon dioxide, and then NH þ 4 and CO 2À 3 are produced from NH 3 5). The beginning of the hydrothermal reaction speeds up the hydrolyzation of urea, and the solution changes into alkaline because of the excessive urea.…”

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

“…During the synthesis procedure of the precursors, 25 mL of 0. 4 6 , or Ni(OH) 2 was placed in a mixture of 10 mL deionized water and 3 mL 1 mg mL À1 HAuCl 4 $4H 2 O solution. For the purpose of achieving good mixing uniformity, the solutions were stirred at room temperature for 4 hours and preserved in three Teon-lined stainless-steel autoclaves at 120 C for 1 hour.…”

“…[1][2][3][4] Among them, metal oxide gas sensors possess obvious advantages such as rapid responsiveness, low cost, high sensitivity and long service life, and account for 60% of gas sensors on the market. [5][6][7][8] Previous studies have shown that metal oxide gas sensors have better sensing performance in the detection of volatile organic compounds (VOC).…”