O-vacancy-containing Ti2CO2 NO gas sensor

Abstract

We investigate the adsorption of nitrogen oxide (NO) on O vacancy containing Ti2CO2 (Ti2CO2-OV) for utilization as a gas sensor using first-principles simulations. NO could be chemisorbed on an oxygen vacancy of Ti2CO2 with distinct charge transfer of 0.224 e. Oxygen vacancy defect provides strong adsorption sites for high signal. In addition, metallization by defect state of Ti2CO2-OV improves conductivity and reduces noise. Therefore, better SNR can be obtained due to these features. We also used the non-equilibrium Green's function (NEGF) method to study the current-voltage (I-V) relationship. The transport properties exhibit distinct responses with dramatic changes of the I−V curve in pristine Ti2CO2 and NO molecule adsorbed on Ti2CO2-OV. However, there is a long recovery time associated with the high binding energy of the adsorption site. Therefore, we demonstrate that Ti2CO2-OV can be encouraging gas sensing materials for detecting NO gas with high sensitivity and excellent SNR, but poor reversibility.