Enhanced Hydrogen Gas Sensing Properties of ZnO Nanowires Gas Sensor by Heat Treatment under Oxygen Atmosphere

Abstract

ZnO nanowires were synthesized and annealed at various temperatures of 500-800 o C in oxygen atmosphere to investigate hydrogen gas sensing properties. The diameter and length of the synthesized ZnO nanowires were approximately 50-100 nm and a few 10s µm, respectively. H 2 gas sensing performance of the ZnO nanowires sensor was measured with electrical resistance changes caused by H 2 gas with a concentration of 0.1-2.0%. The response of ZnO nanowires at room temperature to 2.0% H 2 gas is found to be two times enhanced by annealing process in O 2 atmosphere at 800 o C. In the current study, the effect of heat treatment in O 2 atmosphere on the gas sensing performance of ZnO nanowires was studied. And the underlying mechanism for the sensing improvement of the ZnO nanowires was also discussed.

Annealing Effects on SnO2 Thin Film for H2 Gas Sensing

“…Among them, hydrogen (H 2 ) is attracting attention as a renewable energy source used in various fields, such as automobiles, fuel cells, and chemical industries, because of its environmental friendliness and high energy density characteristics [1,2]. However, H 2 has a flame propagation speed of approximately eight times faster than methane, whereas its minimum ignition energy is approximately 0.06 times lower than methane, which can easily cause a backfire or explosion owing to minor external factors [1,3,4]. To use the H 2 gas in the industry environment, H 2 stability should be ensured, and the detection of gases in the environment containing H 2 is inevitable.…”

“…However, because semiconductor gas sensors are driven at relatively high temperatures, they mainly use a metal-oxidesemiconductor form that is stable at high temperatures. Materials commonly used for metal oxide gas sensors include ZnO [4], SnO 2 [6][7][8], and TiO 2 [1], among which SnO 2 has been extensively studied as SnO 2 film-structured gas sensors exhibit high response results and fast response rates for specific gases, owing to their unique characteristics. SnO 2 is an n-type semiconductor with a wide energy band gap of 3.6 eV and a tetragonal rutile structure caused by oxygen vacancy.…”