Hexagonal Al₂O₃/TiO₂/TiN Nanotubes‐Based Sensor for CO₂ Detection

Abstract

A hexagonal Al 2 O 3 /TiO 2 /TiN nanotube sensor is prepared using an Al 2 O 3 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 TiO 2 and TiN is conducted through atomic layer deposition and DC sputtering techniques, respectively. The application of Al 2 O 3 /TiO 2 /TiN nanotube sensor for the detection of CO 2 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 CO 2 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 CO 2 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 CO 2 gas.