High-Performance Formaldehyde Gas Sensor Based on Cu-Doped Sn<sub>3</sub>O<sub>4</sub> Hierarchical Nanoflowers
Lei Wang, Yang Li, Wenjing Yue, Song Gao, Chunwei Zhang, Zhenxiang Chen
Abstract
Gas sensors with high response, low operating temperature and superior selectivity are highly desired for monitoring toxic gases in the environment. Herein, a formaldehyde (HCHO) gas sensor with outstanding sensing properties is proposed based on Cu-doped Sn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> hierarchical nanoflowers that are synthesized via a facile hydrothermal method. The Cu-doped Sn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> gas sensors exhibit conspicuously improved sensing performance to HCHO compared with the pure Sn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> gas sensor at a relatively low operating temperature of 160 °C. Specifically, the gas sensor based on the 4 wt% Cu-doped Sn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> composite exhibits a high response up to 53 toward 100 ppm HCHO, a fast response time of 5 s, and low detection limit of 1 ppm. In addition, the prepared Cu-doped Sn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> gas sensor possesses conspicuous advantages comprising a good selectivity, perfect reproducibility and excellent long-time stability. The sensing mechanism of the proposed gas sensor is explained by the electron depletion theory, and the possible reasons for the improvement of sensing properties by Cu doping are also discussed. It's strongly believed that the Cu-doped Sn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> sensor has a practical application in HCHO detection.