Near Room Temperature, Fast-Response, and Highly Sensitive Triethylamine Sensor Assembled with Au-Loaded ZnO/SnO<sub>2</sub> Core–Shell Nanorods on Flat Alumina Substrates

Chemiresistive gas sensors with low power consumption, fast response, and reliable fabrication process for a specific target gas have been now created for many applications. They require both sensitive nanomaterials and an efficient substrate chip for heating and electrical addressing. Herein, a near room working temperature and fast response triethylamine (TEA) gas sensor has been fabricated successfully by designing gold (Au)-loaded ZnO/SnO<sub>2</sub> core–shell nanorods. ZnO nanorods grew directly on Al<sub>2</sub>O<sub>3</sub> flat electrodes with a cost-effective hydrothermal process. By employing pulsed laser deposition (PLD) and DC-sputtering methods, the construction of Au nanoparticle-loaded ZnO/SnO<sub>2</sub> core/shell nanorod heterostructure is highly controllable and reproducible. In comparison with pristine ZnO, SnO<sub>2</sub>, and Au-loaded ZnO, SnO<sub>2</sub> sensors, Au-ZnO/SnO<sub>2</sub> nanorod sensors exhibit a remarkably high and fast response to TEA gas at working temperatures as low as 40 °C. The enhanced sensing property of the Au-ZnO/SnO<sub>2</sub> sensor is also discussed with the semiconductor depletion layer model introduced by Au-SnO<sub>2</sub> Schottky contact and ZnO/SnO<sub>2</sub> N–N heterojunction.