Ultra-long Zn2SnO4-ZnO microwires based gas sensor for hydrogen detection

Ultra-long Zn2SnO4-ZnO microwires were synthesized by thermal evaporation of the mixture of SnO2, ZnO and C powders. Microstructural characterization by means of X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy showed that Zn2SnO4-ZnO microwires with excellent crystallinity were 2.8-3.2 μm in diameter and 4.0-4.2 mm in length. The maximal length-to-diameter ratio of Zn2SnO4-ZnO microwires is approximately 1500. H2 sensing properties showed that Zn2SnO4-ZnO microwires exhibited not only excellent reversibility to H2, but also a good linear relationship between the sensor response and H2 concentration. The response time and recovery time decreased as the operating temperature increased. The highest sensor response of 9.6 to 1000 ppm H2 was achieved at an operating temperature of 300 °C. The electron depletion theory was used for explaining H2 sensing mechanism by the chemical adsorption and reaction of H2 molecules on the surface of Zn2SnO4-ZnO microwires.