Improved H2S sensitivity of nanosized BaSnO3 obtained by hydrogen peroxide assisted sol-gel processing

Abstract

Barium stannate is a mixed-metal oxide with a perovskite structure and unique electric, catalytic, and sensing properties. Surface chemistry determines gas sensing behavior, which depends on materials synthesis and processing methods. A novel technique was invented for obtaining BaSnO3 nanoparticles using a hydrogen peroxide assisted sol-gel process. However, to date, the sensing behavior of such prepared barium stannate nanoparticles has not been investigated. In this work, we obtained pure and La-modified BaSnO3 by the hydrogen peroxide-assisted sol-gel method and comparatively studied the composition, microstructure, and gas sensing behavior using as a reference barium stannate prepared by a conventional hydrothermal route. The increased sensitivity and selectivity to H2S were observed for the sol-gel obtained BaSnO3, and the sensing behavior was improved at temperatures higher than 150 °C by La(5%)-modified of barium stannate. The sensing mechanism was revealed by in situ infrared and Raman spectroscopy. The superior sensitivity and selectivity of the sol-gel obtained materials were attributed to lower surface contamination by adsorbed carbonate groups compared to hydrothermally obtained BaSnO3. The surface modification by La3+ species further reduced the carbonate impurity and enhanced the adsorption and oxidation of H2S gas at the BaSnO3 surface.