Creating oxygen vacancies on 2D MoO3-x via a facile annealing process for high performance optoelectronic NO2 gas sensing

The hazards to the ecological environment and human health promote the development of NO 2 monitoring sensors. However, the high operating temperature of traditional metal oxide sensitive materials limits the application of gas sensor-based systems in low power monitoring. Here, we utilize oxygen vacancy enriched 2D MoO 3-x , enabling the high performance optoelectronic NO 2 gas sensing at room temperature. The introduction of oxygen vacancies in MoO 3-x results in the red-shift light absorption from purple light to cyan light and high surface activity with negative potential, thus promoting its application in optoelectronic room temperature gas sensing. Under 365 nm UV light irradiation, oxygen vacancy enriched 2D MoO 3-x based gas sensor shows a good room temperature reversible response towards different concentrations of NO 2 , in which a response factor of 6.46 is achieved towards 10 ppm NO 2 . Moreover, excellent repeatability in six continuous tests, selectivity towards five common gases, and long-term stability for four months were also demonstrated in this sensor. This work provides an effective approach for tuning the electronic structure and surface activity of metal oxide, and demonstrates the application feasibility of oxygen vacancy enriched metal oxide in high optoelectronic gas sensing.