Effects of microstructure of mesoporous SnO2 powders on their H2 sensing properties

Various mesoporous tin dioxide (m-SnO2) powders were prepared from two kinds of combination of a tin source and a surfactant template, and their H2 sensing properties were investigated. The specific surface area and pore volume of the m-SnO2 powder prepared from Na2SnO3·3H2O as a tin source and n-cetylpyridinium chloride monohydrate (C16PyCl; (C5H5NC16H33)Cl·H2O) as a template under a fixed pH value of 10 (m-SnO2(1)) were larger than those of the m-SnO2 powders prepared from SnCl4·5H2O as a tin source and aerosol-OT (AOT; C20H37O7SNa) as a template under different pH conditions (m-SnO2(2)-n; n is the value of pH of the precursor solution). However, the specific surface area of m-SnO2(1) decreased drastically by post-grinding, while m-SnO2(2)-n powders with small secondary agglomerates showed only a slight decrease in specific surface area during post-grinding. In addition, m-SnO2(2)-n sensors exhibited better H2 response and lower resistance than those of m-SnO2(1) sensor, especially at low operating temperatures, probably because of moderately developed mesopores which promoted easier diffusion of H2 to the most sensitive region of the surface of SnO2 particles.