SnO2−In2O3 Nanocomposites as Semiconductor Gas Sensors for CO and NOx Detection

Gas sensors based upon semiconductor metal oxides provide for the safe detection of toxic gases, such as carbon monoxide in households, natural gas in coal mines, and ethanol in fermentation processes. However, they still suffer from several limitations, such as long-term response reproducibility and gas sensitivity and selectivity. The need for thermally stable gas sensor materials that possess ultrahigh sensitivity and selectivity, often in the presence of other adsorbing gases, presents a major challenge. In this work, we have synthesized tin−indium oxide (SnO 2 −In 2 O 3 ) nanocomposites that exhibited superior thermal stability against grain growth. Through the introduction of metal clusters and oxide surface coatings, the SnO 2 −In 2 O 3 nanocomposites achieved superb sensitivity for both reducing and oxidizing gases. Our synthesis method provided an inexpensive and flexible wet-chemical route toward tailoring semiconductor metal oxide nanocomposites for the selective and reproducible detection of toxic or combustible gases at parts per million levels.