Aim of the work is to compare the morphological properties of TiO2 powders obtained by different methods. The microstructure of powders is a fundamental parameter to judge if the material is suitable for gas sensing. Materials for chemical sensors have to be composed by nanometric and spherical shaped grains sintered in controlled conditions aimed to obtain Schottky barriers. We investigated a traditional sol-gel (SG) and an hydrothermal (HY) approach to obtain titanium dioxide powders. The same starting materials were chosen for both SG and HY method, a Ti-organometallic precursor and, as solvent, an hydroalcoholic solution. The work is focused on the different methodology and on the outcome related to the two methods (we describe step by step both of them). HY TiO2 powder shows smaller grains than SG TiO2 maintaining spherical shape. A comparison among different handled HY powders shows the role of dwelling time (at fixed temperature) on the nanostructure of grains. Experimental observations are mainly based on XRD and SEM analyses.
Self-assembled gold nanoparticle monolayers in sol–gel matrices: synthesis and gas sensing applications