Gamma-ray engineered surface defects on zinc oxide nanorods towards enhanced NO2 gas sensing performance at room temperature

Gamma-ray irradiation is a fast and efficient technique that can constructively create various defects in a controlled manner to tune materials’ functionality. In this work, zinc oxide nanorods are hydrothermally grown over flexible polyethylene terephthalate paper substrate and then irradiated with 60Co gamma-ray source to create various defects for possible enrichment towards NO2 gas sensing. The sensors irradiated with gamma-ray show enhanced NO2 responses of 120%, 160%, and 185% for 500 ppb concentration at the irradiation doses of 1.5 kGy, 4.5 kGy, and 6 kGy, respectively, as compared to the pristine sensor response of 80%. Maximum response of 312% is achieved at the irradiation dose of 6 kGy for 1500 ppb of NO2. Overall, this study confirms that the enhanced oxygen vacancies, defect concentration, and increased grain boundaries, caused by gamma-ray irradiation can eventually achieve more than two times better efficiency towards NO2 detection at room temperature (25 ℃) on a flexible based NO2 sensor. [Display omitted] •ZnO nanorods irradiated with different gamma-ray doses are reported for NO2 sensing.•Gamma-ray irradiated sensors achieved more than 2 times response over pristine one.•Maximum response of 312% is achieved at a dose of 6 kGy for 1500 ppb of NO2.•More oxygen vacancies, point defects and grain boundaries lead to better NO2 sensing.