Preparation of macroporous SnO films using PMMA microspheres and their sensing properties to NO and H

• DOI: 10.1016/j.snb.2004.07.024
• Publication Date: 2005-03-03T13:14:28Z
• Authors: Takeo Hyodo; Kazuhiro Sasahara; Makoto Egashira; Yasuhiro Shimizu
• Keywords: 0103 physical sciences; 02 engineering and technology; 0210 nano-technology; 01 natural sciences

Abstract Macroporous SnO 2 (mp-SnO 2 (P- n ); P means polymethylmethacrylate (PMMA) and n = diameter of PMMA microsphere) thick film gas sensors were fabricated by a modified sol-gel method by employing PMMA microspheres ( n = 800, 400, 250 and 150 nm) as a template and SnCl 2 as a tin source. Morphology of mp-SnO 2 films was markedly dependent on the SnCl 2 concentration and the diameter of PMMA microspheres. Especially, the ratio of the thickness of the SnO 2 wall to the diameter of the hollow SnO 2 microsphere seems to increase with decreasing the diameter of PMMA microspheres used. Among the films prepared, mp-SnO 2 (P-250) exhibited the largest response to NO and NO 2 in air at 225 °C, whereas its response transients were relatively slow, indicating low adsorption and desorption speeds of negatively charged chemisorbed NO x species on the SnO 2 surface. On the other hand, mp-SnO 2 (P-800) showed the largest H 2 response among the sensors at temperatures higher than 400 °C. It has been revealed that the thickness and porous structure of the SnO 2 thick films are important factors to determine the sensing properties to NO 2 and H 2 .