Effects of Particle Size on the Gas Sensitivity and Catalytic Activity of In 2 O 3

Nanosized In 2 O 3 powders with different particle sizes were prepared by the microemulsion synthetic method. The effects of particle size on the gas-sensing and catalytic properties of the as-prepared In 2 O 3 were investigated. Reductions in particle size to nanometer levels improved the sensitivity and catalytic activity of In 2 O 3 to i -C 4 H 10 and C 2 H 5 OH. The sensitivity of nanosized In 2 O 3 (<42 nm) sensors to i -C 4 H 10 , H 2 and C 2 H 5 OH was 2-4 times higher than that of chemically precipitated In 2 O 3 (130 nm) sensor. A nearly linear relationship was observed between the catalytic activity and specific surface area of In 2 O 3 for the oxidation of i -C 4 H 10 and C 2 H 5 OH at 275 °C. The relationship between gas sensitivity and catalytic activity was further discussed. The results of this work reveal that catalytic activity plays a key role in enhancing the sensitivity of gas-sensing materials.