Three dimensional network of ZnO tetrapods for use in gas sensing

摘要

We fabricated three dimensional networks of ZnO tetrapods on quartz substrates via a thermal oxidation reaction of Zn powder in air mixed with water vapor. The amount of water vapor in air was found to be a key parameter in controlling the yield of tetrapods and thus the formation of the network of tetrapods. The total oxygen amount was helpful in fine tuning the dimension of the tetrapods so as to obtain thin and long tetrapod legs which are essential in building the network of tetrapods. Tetrapod networks were tested as a gas sensing element by measuring changes in their electrical resistances upon exposure to ethanol vapor. The optimum operating temperature of the tetrapod network used as a gas sensing element was in the 400-500 ℃ range. Ethanol concentration as low as 500 ppb was detected with a response larger than 2, suggesting a high sensitivity to ethanol vapor for this novel structure. The response time to gas exposure of a dense tetrapod network consisting of tetrapods having thin and long legs was as fast as 10 sec, pointing to superior properties of the tetrapod network over standard gas sensing elements.