Modified impregnation synthesis of Ru-loaded WO3 nanoparticles for acetone sensing

In this paper, WO3 nanoparticles in a lamellar-structured were fabricated via an acidification method and the surface of nanoparticles were catalytically modified by Ru through a modified impregnation method based on an electronic adsorption mechanism. Gas sensors based on neat and Ru-loaded WO3 nanoparticles were fabricated based on screen printing and sensor responses of acetone were evaluated under a dry and humid ambient, respectively. Experimental results clearly indicated that most of Ru was removed from the WO3 during the washing process, however, a strong sensitization effect of Ru was achieved with a very few loading amount. Accordingly, the basic sensitization mechanism of Ru was investigated based on TPR results and oxygen adsorption behaviors. It is revealed that Ru is loaded on the surface with an oxidized state contributing to an electronic sensitization effect. In addition, Ru on the surface of WO3 as a catalyst significantly enhanced the activity of surface lattice oxygens. As a consequence, surface lattice oxygens could also react with acetone and reduce sensor resistance leading to a sensitization effect. However, we do not expect that reactions of lattice oxygens dominate the sensing process.