Pt-doped In<inf>2</inf>O<inf>3</inf>nanoparticles prepared by flame spray pyrolysis for NO<inf>2</inf>sensing

Abstract

© 2016, Springer Science+Business Media Dordrecht. Abstract: Undoped In2O3and 0.25–1.00 wt% M (M=Pt, Nb, and Ru)-doped/loaded In2O3nanoparticles were successfully synthesized in a single-step flame spray pyrolysis technique using indium nitrate, platinum (II) acetylacetonate, niobium ethoxide, and ruthenium (III) acetylacetonate precursors. The undoped In2O3and M-doped In2O3nanoparticles were characterized by Brunauer–Emmett–Teller (BET) analysis, X-ray diffraction (XRD), and scanning and transmission electron microscopy (SEM & TEM). The BET average diameter of spherical nanoparticles was found to be in the range of 10.2–15.2 nm under 5/5 (precursor/oxygen) flame conditions. All XRD peaks were confirmed to correspond to the cubic structure of In2O3. TEM images showed that there is no Pt nanoparticle loaded on In2O3surface, suggesting that Pt should form solid solution with the In2O3lattice. Gas sensing studies showed that 0.5 wt% Pt doping in In2O3nanoparticles gave a significant enhancement of NO2sensing performances in terms of sensor response and selectivity. 0.5 wt% Pt/In2O3exhibited a high NO2response of ~1904 to 5 ppm NO2at 250 °C and good NO2selectivity against NO, H2S, H2, and C2H5OH. In contrast, Nb and Ru loading resulted in deteriorated NO2response. Therefore, Pt is demonstrated to be an effective additive to enhance NO2sensing performances of In2O3-based sensors. Graphical Abstract: [Figure not available: see fulltext.]