Gas Sensors: Ultrasensitive and Highly Selective Gas Sensors Based on Electrospun SnO₂ Nanofibers Modified by Pd Loading (Adv. Funct. Mater. 24/2010)

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.

Nanoparticles meet electrospinning: recent advances and future prospects

“…45 This method is a compact way to fabricate NPs-polymer hybrid fibres, and many NPs have been synthesized on the electrospun fibres, such as Au, Ag, Pd, Pt, TiO 2 , WO 3 , SnO 2 . [46][47][48][49][50][51] A requirement is the electrospun polymer fibres does not dissolve in the colloidal solution.…”

Improving CO2 Electroreduction Activity by Creating an Oxygen Vacancy-Rich Surface with One-Dimensional In–SnO2 Hollow Nanofiber Architecture

“…41 As In 3+ did not replace Sn 4+ in SnO 2 crystal lattice to cause microstrain and defects, the mean grain size is the main factor that should be taken into account. In this case, tiny In 2 O 3 nanocrystallite segregates on the surface of SnO 2 tetragonal crystal to form grain boundary pinning 42,43 and prevent them from grain migration, 44 as clearly shown in Figure 1f. As expected, the size of SnO 2 particles, calculated through diffraction peak (110) and Scherrer's formula, 45 becomes smaller with the increase of In-doping amount (Figure 2b and Table S1), which could In:Sn atomic ratio of about 1:60 and then decreases due to the aggregation of In 2 O 3 nanocrystallites.…”