Preparation of In2O3 microtubules with abundant oxygen vacancies at room temperature and their chlorine gas sensing properties

ABSTRACT

Because of the outbreak of COVID-19 pandemic, the disinfectants have become a daily necessity. The chlorine gas is an important industrial raw material for disinfectants. And the demand of chlorine gas is increasing. As is known to all, chlorine gas is a toxic gas and harmful to health. However, the gas sensors based on common metal oxide semiconductor are not sensitive to low concentrations of chlorine gas. Therefore, it is of great significance to develop the gas sensing materials based on metal oxide semiconductor that are high sensitivity to trace leakage of chlorine gas. In this work, In2O3 microtubules were synthesized by bio-template method with degreasing cotton. In2O3 microtubules was simply treated with NaBH4 reduction and In2O3 microtubules with abundant oxygen vacancies were successfully prepared at room temperature. The effects of the method on the crystal structure, morphology and oxygen vacancies were investigated by means of XRD, SEM, XPS and EPR. The results showed that this method could effectively enhance the concentration of oxygen vacancies in In2O3 materials without the destruction on crystal structure and morphology. In the gas sensing tests, the gas response of In2O3 microtubules with NaBH4 treatment was about 13 times higher than In2O3 microtubules to the same low concentration of chlorine gas. In another word, the In2O3 microtubules were more sensitive to low concentration of chlorine gas after NaBH4 treatment. According to the analysis of gas sensing mechanism, chlorine gas molecule was not only directly adsorbed on the material surface but also oxygen vacancies of material surface. Thus it can be seen that the oxygen vacancies on material surface played an important role in chlorine gas-sensing performance. Because there are more oxygen vacancies in the In2O3 microtubules treated by NaBH4 than the untreated, the In2O3 microtubules with abundant oxygen vacancies exhibited excellent sensitivity to low concentration chlorine gas. © 2022, Editorial Board of Journal of Functional Materials. All right reserved.