(CuO-Cu2O)/ZnO:Al heterojunctions for volatile organic compound detection

• Published in: Sensors and actuators. B, Chemical Chemical, 2018-02, Vol.255, p.1362-1375
• Main Authors: Hoppe, Mathias, Ababii, Nicolai, Postica, Vasile, Lupan, Oleg, Polonskyi, Oleksandr, Schütt, Fabian, Kaps, Sören, Sukhodub, Leonid F., Sontea, Victor, Strunskus, Thomas, Faupel, Franz, Adelung, Rainer
• Format: Article
• Language: English
• Subjects: Air monitoring; Air quality; Aluminum; Annealing; Butanol; Chemical industry; Chemical synthesis; Copper; Copper oxide; Copper oxides; Cu2O; CuO; Cuprite; Dependence; Detection; Environmental monitoring; Gas sensors; Glass substrates; Heterojunctions; Humidity; Indoor air pollution; Operating temperature; Organic chemistry; p-type; Pollutants; Relative humidity; Tenorite; Thickness; VOC sensor; VOCs; Volatile organic compound detection; Volatile organic compounds; Zinc oxide
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2017.08.135

In this work, a simple and cost-efficient method to synthesize a multilayered (CuO-Cu2O)/ZnO:Al nanostructured film forming non-planar heterojunctions for efficient detection of volatile organic compound vapors is presented. The highest gas response of ∼200% to 100ppm of n-butanol at 350°C operating temperature was observed in the case of a layer thickness of CuO-Cu2O ∼20nm on top of the ZnO:Al SCS samples. In this case, the enhanced response was attributed to the involvement of (CuO-Cu2O)/ZnO:Al interface junctions in the gas sensing mechanism. This top layer allows for the formation of an additional enclosed depletion layer, which leads to a higher modulation of the CuO-Cu2O resistance and thus to a higher gas response. The (CuO-Cu2O)/ZnO:Al heterojunction also showed a reduced dependence of the sensing properties with respect to humidity, which is very important for ambient gas sensing applications and VOCs vapor detection in human breath analysis, chemical industry, in outdoor and indoor air quality monitoring. [Display omitted] •CuO-Cu2O/ZnO:Al heterojunctions for selective volatile organic compound detection by a simple technology.•The gas response of ∼200% to 100ppm of n-butanol for a layer thickness of CuO-Cu2O ∼20nm on top of the ZnO:Al SCS samples.•The enhanced response was attributed to the involvement of (CuO-Cu2O)/ZnO:Al interface junctions in the gas sensing mechanism.•The (CuO-Cu2O)/ZnO:Al heterojunction showed a reduced dependence of the sensing properties with respect to humidity. Detection and differentiation of volatile organic compounds (VOC) is highly important since these gaseous pollutants degrade the air quality and represent, even in small amounts, a threat to human health. In this work, a simple and cost-effective method to synthesize a multilayered (CuO-Cu2O)/ZnO:Al nanostructured film forming non-planar heterojunctions for efficient detection of volatile organic compound vapors is presented. While the ZnO:Al layer with different contents of Al (∼0.1 and 0.2 at%) was deposited on a glass substrate via a synthesis from chemical solutions (SCS, at a temperature