Abstract
A hexagonal Al2O3/TiO2/TiN nanotube sensor is prepared using an Al2O3 template. This template is prepared through the Ni imprinting and two-step anodization technique. After the pore widening process, the pore diameter is 300 nm. The deposition of TiO2 and TiN is conducted through atomic layer deposition and DC sputtering techniques, respectively. The application of Al2O3/TiO2/TiN nanotube sensor for the detection of CO2 gas is carried out under different flow rates of this gas from 50 to 150 SCCM. This application is carried out using electrochemical measurements (Keithley device) to determine the current-voltage and resistance time relations. From the measurements, the sensitivity of the sensor increases from 3.2% to 16.4% with increasing the concentration of the CO2 gas from 50 to 150 SCCM, respectively. Moreover, the prepared sensor has a great response time and recovery time of 3 and 35 s, respectively. This behavior qualifies the sensor for industrial applications. Moreover, the limit of detection is very small (6 SCCM). A simple mechanism is mentioned to explain the physical attraction of CO2 over the sensor surface, in which the greatly prepared tubes play the main role in enhancing the sensitivity and response percent of the sensor to CO2 gas.