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

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.