A hybrid room-temperature chemiresistive gas sensor assisted by field ionization of nanowires

Abstract This paper presents a novel gas sensor based on ionization-assisted chemiresistive mechanism. Several volatile organic compounds at ppm level can be differentiated through the physical field gas ionization by CuO nanowires followed by the chemical adsorption forward a molybdenum oxide electrode. Supplemented by the pre-ionization of nanotips, an elevation of chemiresistive response toward acetone up to 16 times has been achieved at room temperature. On the other hand, the chemosensitive oxide layer provides an additional resistance signal to the gas discharge current and threshold voltage of the ionizer, resulting in a higher gas susceptibility. The gas sensing signals including gas discharge current, threshold voltage, and chemiresistance can be interpreted by the gas ionization followed by adsorption mechanism in sequence. Both the ionization energy of the target gas and adsorption energy of ionized gas fragment deduced by the first-principles calculations perform plausible counterparts to the gas selectivity, and the opposite responses have been elucidated by the different charge transfer preferences between the ionized and neutral acetone molecule. This nanowire based hybrid ionization-chemiresistance device may provide a new route to efficiently identify the organic gases.