IMPROVING SENSITIVITY OF ZnO NANORODS FOR THE APPLICATION OF GAS SENSORS AT LOW TEMPERATURES: A REVIEW

Zinc oxide (ZnO) is a nontoxic, affordable, plentiful, and chemically stable substance. Harmful and low concentration gases are detected by using ZnO nanorods because of range of conductance, response towards of oxidative, sensitive and selective properties.This paper review on various fabrication process of ZnO nanorods and their modifications for improving sensitivity for gas sensors at low temperatures. Fabrication methods of Zinc Oxide Nanorods comprise of hydrothermal method, microemulsion, microwave-assisted hydrolysis preparation, gas-solution-solid method and so on. ZnO Nanorods during the fabrication can be controlled by selective growth, control growth and regulating its diameter. Zinc Oxide Nanorods can be modified by doping, surface functionalization and sensitizing the sensing layer with metals and metal oxides.Due to ZnO's limited operation at low temperatures, the majority of research is focused on detecting gases at high working temperatures (200-500C), which would inevitably increase energy consumption and reduce sensor lifespan. Finally, the problems and potential development directions of ZnO-based gas sensors at low temperatures are discussed.