Improvement of the gas sensing response of nanostructured LaCoO3 by the addition of Ag nanoparticles

LaCoO3 decorated with nanoparticles of noble metals has been proposed as catalyst in Suzuki reactions, automotive catalytic converters and gas sensors. In this work, LaCoO3 decorated with silver nanoparticles (AgNPs) was prepared by the solution-polymerization method, using polyvinyl alcohol (PVA) as polymerizing agent. For comparative purposes, LaCoO3 was also synthesized by this method. Calcination at 500 °C produced LaCoO3; however, better crystallinity was obtained at 700 °C. To attach AgNPs to LaCoO3, a simple wet impregnation process was used. The microstructure of samples displayed interconnected nanoparticles and extensive porosity. Ag-LaCoO3 shows AgNPs with average size of 10 nm. Gas sensing characterization performed at 250 °C revealed high reproducibility for detecting CO, CO2 and excess O2 (in air). The results obtained from Ag-LaCoO3 exhibit better stability and the quantitative detection of the test gases. In conclusion, surface decoration of LaCoO3 with AgNPs resulted in an effective and low-cost approach to improve the gas sensing properties of LaCoO3. This process can also be used to enhance the gas response of other oxide perovskites.