Ultrasensitive and Highly Selective Gas Sensors Based on Electrospun SnO₂ Nanofibers Modified by Pd Loading

Abstract

This work presents a new route to suppress grain growth and tune the sensitivity and selectivity of nanocrystalline SnO2 fibers. Unloaded and Pd‐loaded SnO2 nanofiber mats are synthesized by electrospinning followed by hot‐pressing at 80 °C and calcination at 450 or 600 °C. The chemical composition and microstructure evolution as a function of Pd‐loading and calcination temperature are examined using EDS, XPS, XRD, SEM, and HRTEM. Highly porous fibrillar morphology with nanocrystalline fibers comprising SnO2 crystallites decorated with tiny PdO crystallites is observed. The grain size of the SnO2 crystallites in the layers that are calcined at 600 °C decreases with increasing Pd concentration from about 15 nm in the unloaded specimen to about 7 nm in the 40 mol% Pd‐loaded specimen, indicating that Pd‐loading could effectively suppress the SnO2 grain growth during the calcination step. The Pd‐loaded SnO2 sensors have 4 orders of magnitude higher resistivity and exhibit significantly enhanced sensitivity to H2 and lower sensitivity to NO2 compared to their unloaded counterparts. These observations are attributed to enhanced electron depletion at the surface of the PdO‐decorated SnO2 crystallites and catalytic effect of PdO in promoting the oxidation of H2 into H2O. These phenomena appear to have a much larger effect on the sensitivity of the Pd‐loaded sensors than the reduction in grain size.

Enhanced sensitive and selective xylene sensors using W-doped NiO nanotubes

“…Consequently, a simple method is needed to detect xylene. In recent years, gas sensor based on metal oxide semiconductor nanomaterials, such as SnO 2 [7][8][9][10], WO 3 [11][12][13][14], In 2 O 3 [15][16][17][18] and NiO [19][20][21][22], has attracted much attention for harmful, environmental, explosive and toxic gas detection, and they are possible candidates as xylene sensors due to their advantages of high response to target gases, simplicity in preparation and costeffective. However, the design of high performance xylene sensors based on semiconductor is still in the early stages of investigation.…”

Sb–SnO2 nanoparticles onto kaolinite rods: assembling process and interfacial investigation

“…, Sn 4? and Sn(-Cl) complex, respectively, the former two corresponded to SnO and SnO 2 , the latter may be resulted from the reaction between the Sn ions and Clfrom the reaction environment (Li et al 2006;Yang et al 2010). After the precursor was calcined at 700°C, the Sn 2?…”

“…The peak at 532.1 eV of O 1s was attributed to the Al-O and Si-O from the substrate and the chemisorbed oxygen or hydroxyl ions such as O -, O 2-or OH -on the SnO 2-d surface, the higher intensity of this peak in the precursor than that in SK20 indicated the existence of SnO 2 ÁxH 2 O and hydroxyl from kaolinite. The peak around 533.1 eV was directly associated with H 2 O on the surface (Montilla et al 2004;Manesse et al 2009;Yang et al 2010). The analysis of the surface Sb was restricted to the Sb 3d3/2 lines because of the overlap of the O 1s and Sb 3d5/2 lines, and Sb transition (3d3/2) was employed to obtain the oxidation state of antimony.…”

EFFECT OF ANNEALED TEMPERATURE ON NO2 GAS-SENSING PERFORMANCES OF SnO2 NANOWIRE SENSORS

“…Therefore, the development of gas sensors for the detection of such gases has attracted considerable interest in recent years [1]. Many metal oxide semiconductors including ZnO, SnO 2 , WO 3 and In 2 O 3 have been applied for gas sensors [2]. Among them, SnO 2 has been emerged as one of the most promising candidate due to its high sensitivity [3], good selectivity [4] and low cost [5].…”