Oxygen Vacancy Engineering And Superior Sensing Properties Of Hematite Prepared Via A One-Step Treatment

Despite being difficult to control and identify, extremely dilute oxygen vacancies that are generally present in metal oxides have been widely reported to play an important role in tuning the performance of gas sensors. The conventional methods of oxygen vacancy regulation, i.e., oxygen vacancy engineering, require sophisticated equipment and complex procedures while being time/energy-consuming. Beyond that, the mechanisms underlying sensing properties and oxygen vacancies have not been well understood for a long time, in particular, lack quantitative relationship. An open and important question is whether and to what extent the enhanced sensing properties can be attributed only to oxygen vacancies. In this study, a facile one-step ?shake and heat? treatment that simply consists of mixing the metal oxide with carbohydrate and then heating the mixture is employed to prepare controllable oxygen-vacancy hematite. The oxygen vacancy concentration of hematite is measured by a gravimetric method. The oxygen vacancy-rich hematite shows superior sensing properties toward acetone compared to the raw materials and traditional argon annealed samples. There is a 220% increase in response when the oxygen vacancy concentration reaches 1.6% and a 74% increase when the oxygen vacancy concentration is 0.4%. The enhanced sensing properties are proven to be attributed only to the oxygen vacancies in hematite by the subsequent oxygen annealing experiment. Our study provides a simple and effective synthesis strategy to prepare high-performance oxygen vacancy-rich metal oxide sensors as well as a semiquantitative relationship between sensing performance and oxygen vacancies.