Novel CO2and CO gas sensor based on nanostructured Sm2O3 hollow microspheres

Abstract

Sm2O3 microspheres were prepared by the coprecipitation method, using samarium nitrate and formic acid. The size of the microspheres was in the range 1-6μm; however, extensive fragmentation was observed. An outstanding improvement of the microstructure was achieved by using an aqueous solution of pectin. In this case, hollow and nanoporous microspheres, having little fragmentation, were produced. The evolution of the crystal structure with calcination temperature revealed the formation of single-phase cubic Sm2O3, at 600 °C. The effects of the calcination temperature and the concentration of samarium nitrate, on the microstructure of Sm2O3, were investigated. For the gas sensing characterization, thick films were prepared with the as-prepared Sm2O3 microspheres. The gas sensing performance of Sm2O3 sensor devices was enhanced when gold electrodes were used. Transient impedance measurements revealed a reproducible and reliable detection of carbon dioxide and carbon monoxide at 400 °C. The increase of the applied frequency produced stable and noiseless graphs. Furthermore, quantitative detection of the test gases was revealed by impedance and polarization measurements.