Highly Sensitive and Fast-Response Volatile Organic Compounds Sensors Based on Star-Shaped BaTiO₃/ZnO Heterostructures

Abstract

Integrating different semiconductor materials, taking merits of each component's advantages and synergistic properties, hold great promise to enhance the performance of gas sensors. In the present study, a multistep fabrication process, involving the environment-friendly hydrothermal process and simple sol-gel techniques is proposed for the fabrication of star-shaped BaTiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /ZnO heterostructures based sensors. Sensors with different molar ratios of BaTiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> to ZnO were fabricated and exploited for the detection of volatile organic compounds. Characterizations of the BaTiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /ZnO heterostructures using X-ray diffraction spectroscopy, field emission scanning electron microscopy, and energy dispersive spectroscopy provided clear evidence of high-purity star-shaped heterostructure formation. Gas sensing measurement results illustrate that the BaTiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /ZnO heterostructure based sensor with a molar ratio of 1:2 exhibits an abrupt and reliable gas response to ethanol and acetone at the optimum working temperature of 300 °C. Moreover, the BaTiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /ZnO heterostructure sensor with a molar ratio of 1:3 shows a significant response to methanol at the optimum working temperature of 260 °C. The enhanced sensing characteristics of the sensor are attributed to the formation of heterojunctions at the interface of BaTiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> and ZnO and surface area enhancement provided by its star-shaped morphology.