Yolk-shell microspheres perovskite Gd/Fe oxides with rich oxygen vacancies for ultra-sensitive properties in acetone detection

Acetone as a toxic and hazardous gas is widely appeared in life. In this paper, p-type Gd/Fe oxide yolk-shell microspheres were prepared by a one-step hydrothermal method. Characterization and test results shows that perovskite Gd/Fe oxides with yolk-shell microspheres possess abundant oxygen vacancies, which presents excellent acetone gas-sensitive performance. Among the obtained sensor, the optimal operating temperature of the S-4 (Gd0.77/Fe) sensor is reduced to 200 ℃, and the response value (S = 20) to 100 ppm acetone is improved by 5 times (compare to S-1). The lowest detection limit can be as low as 0.5 ppm, furthermore the sensor presents resist-humidity. Electron paramagnetic resonance (EPR) and x-ray photoelectron spectroscopy (XPS) results reveal that the ratio of Gd/Fe has a strong correlation with the content of oxygen vacancies. The rich oxygen vacancies control theory is the main reason for improving gas sensing performance in this work. The presence of oxygen vacancies effectively increases the active sites and further promotes intermolecular interactions. Overall, the sensor S-4 (Gd0.77/Fe) has an important potential in the detection of acetone in human breath with high response and low detection limit under high humidity environment.