Synthesis and Analytical Characterization of Composite Nanomaterials for NOx Sensors

The control of pollutants emission from internal combustion engines is a worldwide issue, in the automotive field. The roadmap for the reduction of vehicle emission limits is driving the academic and industrial interest towards the development of innovative systems integrating novel detection elements and fast feedback circuits and actuators. Based on a tighter control over emissions, and starting from 2014, Euro 6 standards are expected to improve the environmental compatibility of a new generation of vehicles in Europe. This scenario calls for a significant improvement of the sensors technologies for the detection of the main pollutants related to the automotive field, including nitrogen oxides (NOx). In this work, we report on the synthesis and analytical characterization of hybrid nanocomposites containing gold nanoparticles (Au-NPs) and metal oxide nanostructures (MO-NPs, such as zirconium oxide, indium oxide, oxide mixtures, etc.). These species are promising for real-time detection of low levels of NOx species, owing to their low cost, high sensitivity and availability under a variety of stoichiometric and mixing ratios, showing different gas sensing characteristics [1- 2]. Different MO-NPs and mixed MO-NP systems were prepared using a simple but efficient sol-gel method. Subsequently, the nano-oxides were electrodecorated by Au-NPs. Since Au nanophases exhibit pronounced selectivity toward NOx gases [3], the resulting hybrid nanocomposites are expected to improve the nanomaterial sensing performance. All the nanomaterials were characterized using FTIR, XPS, XRD, TEM, and SEM techniques. Experimental evidences support further application of these NPs as active elements in novel NOx sensors