Preparation of Mesoporous and meso-macroporous SnO2 powders and application to H2 gas sensors

Mesoporous SnO2 (mp-SnO2) and meso-macroporous SnO2 (m-mp-SnO2) pellet-type gas sensors were fabricated by the sol-gel method employing SnCl4-5H2O as a Sn source. The mesoporous structure was controlled by C20H37O 7SNa, while the macroporous structure was controlled by polymethylmethacrylate (PMMA) microspheres. The introduction of macropores by the addition of PMMA microspheres into mp-SnO2 tends to increase the pore diameter and crystallite size. The large amount of macropores introduced into mp-SnO2 sensors by the addition of PMMA microspheres in the preparation process significantly increased the resistance of all the sensors. Among all those tested, the mp-SnO2 sensor with only 5 wt% Sb 2O5 added exhibited the largest response at 400°C. The 70% response and recovery times could be reduced by the introduction of macropores