Self-decoration of Barium Titanate with Rhodium-NP via a facile co-precipitation route for NO sensing in hot gas environment.

Abstract

There is an urgent need for the development of real-time gas sensors, capable of detection under hot-gas (> 400 °C) flow for instance to control exhaust emissions. In this context, Rh-doped BaTiO3 has been prepared by co-precipitation route and heat-treated at 900 °C under 2% hydrogen to obtain in-situ Rh-nanoparticle decoration of submicron BaTiO3 powder. X-Ray diffraction, Raman and X-Ray photoelectron spectrometry analysis confirm the presence of Barium Titanate phases and the substitution of Ti4+ by Rh3+. According to the analytic evidences, thermal hydrogen treatment leads probably to the diffusion of Rhodium out of titanate lattice yielding a self-decoration of the nano-sized Barium Titanate particles. Further NO-sensing tests of the sensors produced by deposition of this in-situ Rh-loaded BaTiO3 on IDE revealed, for the first time, the achievement of significantly increased selectivity and NO sensing response (e.g. R/R0 = 18 % for 200 ppm NO) under hot-gas environment (synthetic humid air as carrier gas at 900 °C) The calculated response and recovery times are reasonable and observed reproducibility confirms suitability to practical applications. Relying on the carried investigations, this good sensing performance can be explained by creation of excessive oxygen vacancies resulting through the surface diffusion of rhodium. Moreover, it is to claim that the excellent catalytic activity of rhodium plays a key role in the enhancement of NOxsensing.