Solvothermal Synthesis Of In₂O₃ For Acetone Detection

Acetone is widely used in daily life,scientific research and industrial production with the characteristics of good solubility and high activity.However,due to the toxicity of acetone and its environmental hazards,people should monitor its concentration to develop prevention strategies.Meanwhile,acetone is a biomarker for diabetes,lung cancer,congestive heart failure and other diseases.Therefore,it's significant to improve the accuracy of acetone detection for health protection,pollution prevention and clinical diagnosis.As a main detection method of acetone gas,metal oxide semiconductor gas sensor has been widely studied for its low cost,easy integration and portability.However,some disadvantages such as poor selectivity,poor repeatability and high detection limit still restrict its applications.The main interference gas for acetone detection is ethanol.SnO₂ semiconductor material,which is frequently used to fabricate commercial gas sensor,usually has identical sensitivity to the same concentration of acetone and ethanol.In other words,SnO₂ sensor cannot detect acetone gas selectively.In₂O₃ is a kind of wide band gap semiconductor with high reactivity.The performance of In₂O₃ gas sensor can be improved by adjusting microstructure and interface performance.The methods are developing porous structural and constructing heterojunction.In this paper,In₂O₃ was selected as gas sensing material,and acetone was the target gas.By controlling morphology and crystal structure of the material,sensitivity of acetone gas was enhanced,and the influence of ethanol gas was reduced.In this way,selective identification of acetone gas was realized.Firstly,we synthesized porous In₂O₃ cube by solvothermal method.Compared with commercial In₂O₃ particle,sensitivity and response/recovery speed of In₂O₃ cube to acetone had been greatly improved.The screening ability to indistinguishable ethanol gas had also been enhanced.Afterwards,sensitivity and selectivity of acetone sensor was further improved by preparing mixed-phase In₂O₃ flower.The main contents are as follows:1.Porous In₂O₃ cube was prepared by one-step solvothermal method with high-temperature calcination.Crystal structure and morphological characterization indicated that the as-synthesized sample was porous cube with the diameter of 50 nm.The pore size distribution centered at approximately 24 nm.According to gas sensing test,the sensor based on porous In₂O₃ cube showed improved sensing properties to acetone.Compared with In₂O₃ solid nanoparticles purchased,it exhibited a 2.2 times higher response and shorter response/recovery time.Response and recovery time was reduced to only 1/6 and 1/2 of the commercial-In₂O₃-based sensor,respectively.In addition,the ratio of response to acetone and ethanol increased from 1.4 to 1.8,indicating that the screening capacity of sensor based on porous In₂O₃ cube for ethanol was improved.The regular microstructure of the In₂O₃ cube caused large gaps,which promoted rapid diffusion of gas in the sensitive body and contributed to an ultrafast response speed?1s?.The porous structure allowed a full contact between target gas and sensitive surface,improving sensitivity by increasing the specific surface area.2.The porous nanosheet-based In₂O₃ micro flower with mixed phase was synthesized by solvothermal method combined with high temperature calcination.The nanosheet unit was only 7.6 nm thick,and there were two crystal phases on the same nanosheet,namely cubic bixbyite type and rhombohedral corundum type.The response of the device to 50 ppm acetone reached 12.0,but it was only 2.9 for ethanol.Compared with In₂O₃ cube,sensitivity of this material to acetone had been enhanced,and anti-interference ability to ethanol had also been further improved.These results showed that construction of heterostructure not only improved the response to acetone,but also contributed to the enhancement of selectivity.The heterostructure improved the catalytic activity of acetone and suppressed the activity of ethanol interference gas,thereby achieving the selective identification of acetone.In addition,small size effect caused by ultra-thin nanosheet units also contributed to the increase of sensitivity.