DONG Jiale, ZHU Jiejun, YAN Rui, ZHENG Jiaoling, CHEN Yuping, GAO Liping
(Department of Material and Chemical Engineering, Chuzhou University, Chuzhou 239000, Anhui, China)

Abstract: Porous In₂O₃ nanosheets were synthesized by using a hydrothermal method. The effects of the type of solvent and the reaction time on morphology of the materials were studied, while the crystal growth mechanism of the nanosheets was discussed. Sensitive performance of the porous In₂O₃ nanosheets in the form of parathermal semiconductor sensor to formaldehyde gas was studied. Phase composition and morphology of the samples were characterized by using XRD and SEM. It was observed that the material underwent a phase change as the reaction time was gradually increased. After reaction for 24 h, porous In₂O₃ with hexagonal crystal structure was formed. The average lateral size and thickness of the nanosheets were about 1 μm and 50 nm, respectively. The In₂O₃-based sensor exhibited a sensitivity of 8 to 50 ppm formaldehyde at 330 ℃, with response time and recovery time of 14 s and 5 s, respectively. Due to the porous structure of the material, the formaldehyde gas molecules can be adsorbed and desorbed quickly. The lowest concentration of formaldehyde that could be detected by the sensor was 1 ppm, while the sensor had a linear sensitivity over the formaldehyde concentration range of 1-100 ppm.

Key words: In₂O₃ porous nanosheets; growth mechanism; formaldehyde; gas-sensing properties