Enhancing visible light-activated NO₂ sensing properties of Au NPs decorated ZnO nanorods by localized surface plasmon resonance and oxygen vacancies

Increasing light absorption is of crucial importance for optimizing light-activated gas detection. However, the relevant research is still far from sufficient. Herein, a high performance visible light-activated NO₂ gas sensor is developed relied on the localized surface plasmon resonance (LSPR) and increased surface oxygen vacancies. Au NPs decorated ZnO nanorod array as sensitive materials was synthesized via a two-step low temperature hydrothermal process. The influences of Au decoration and light wavelength on the sensing behaviors were systematically investigated. It is found that the Au NPs decoration can largely promote the visible light-activated gas sensing properties in comparison with pure ZnO film. In addition, the as-prepared sensors demonstrate excellent repeatability and selectivity as well as moisture stability. Moreover, the sensing mechanism based on LSPR was discussed in detail. This work not only sheds some lights on the fundamental understanding for the LSPR enhanced gas sensing mechanism, but also offers an approach in constructing high-performance light-activated gas sensor. (paper)