Enhanced Sensitivity and Recovery Time of ZnO/SWCNTs-Based Nitric Oxide Gas Sensor Utilizing Photo-Stimulated Desorption Method at Room Temperature Environment

Nitric oxide (NO) is a colorless, odorless gas that is highly reactive with oxygen in the air. NO gas causes environmental problems and explosions in both life and industrial settings; therefore, NO gas detection is necessary to prevent these issues. Previous research has focused on detecting NO gas using sensors that typically operate at high temperatures, between 160 and 300°C. Sensors operating at high temperatures require high power consumption and are not portable, making it necessary to develop NO gas sensors that can operate at room temperature. Single-walled carbon nanotubes (SWCNTs) have a large specific surface area, excellent thermal conductivity, and high tensile strength, making them suitable for use in wearable sensors. Zinc oxide (ZnO) possesses excellent physical and chemical properties, along with advantages such as chemical stability, environmental friendliness, and low synthesis cost. In this work, a ZnO/SWCNTs-based NO sensor will be fabricated to provide a rapid and excellent response and recovery rate to NO gas, even at room temperature. The NO sensor based on pristine SWCNTs exhibited a response of 4.17% at an NO gas concentration of 50 ppm. However, the NO sensor based on ZnO-decorated SWCNTs showed a significant improvement with a response of 32.94% at the same concentration, an enhancement of 28.77%. Despite this improvement, the recovery rate was low. To address this issue, an external light source was used, resulting in remarkable changes. Using a UV light source (405 nm) led to fast recovery rates, a phenomenon attributed to photostimulated desorption (PSD). The recovery time was reduced from over 2400 seconds to 83 seconds at an NO concentration of 100 ppm, a reduction of over 2317 seconds. Therefore, utilizing the high sensitivity and recovery rate of the NO gas sensor based on ZnO/SWCNTs developed in this study, it can prevent atmospheric pollution and explosion accidents caused by NO gas leakage even at room temperature.