Synthesis Of Indium Oxide Nanocomposites And Its Gas Sensing Studies

Indium oxide(In2O3)is an important wide band gap semiconductor sensing material with excellent optical and electrical properties and chemical stability.However,the traditional In2O3 sensors suffer from many problems associated with high working temperature,low response and poor selectivity,which restrict its practical application.Based on these problems,we improved the gas-sensing performance through modification of morphology,transition metal doping and noble metal loading.In this work,rod-like Co-doped In2O3 and flower-like Au-loaded In2O3 nanocomposites were prepared by hydrothermal method.The morphologies,structures and sensing mechanisms of the nanocomposites were studied in detail with various characterization methods.The details are as follows:1.One-step synthesis of Co-doped In2O3 nanorods with different molar ratios were prepared and their HCHO gas sensing properties were studied systematically.The nanorods with width and length of 10?20 nm and 40?60 nm,respectively.Small-sized nanorods have a large specific surface area,which could provide abundant reaction sites to gas molecular diffusion and enhance the response of the sensor.The effect of Co doping on the gas sensing properties of the material was analyzed by a series of characterization methods.Results showed that the In2O3/1%Co displayed a higher response of 23.2 for 10 ppm of HCHO than that of pure In2O3 by 4.5 times at 130 ?.Simultaneously,the In2O3/1%Co also showed excellent selectivity and long-term stability.The outstanding gas sensing performance were mainly attributed to the incorporation of Co,which suggested the important role of the amount of oxygen vacancies and adsorbed oxygen in improving HCHO sensing properties of In2O3 sensors.2.Au-loaded In2O3 nanocomposites with different molar ratios were obtained by a simple strategy for the detection of C2H5OH.The morphology,structure and gas sensing mechanism were investigated.The results showed that the 1.0%Au/In2O3 sensor exhibited a high response of 505 towards 50 ppm C2H5OH at 250 ?,which is much better than that of other sensors.Meanwhile,the 1.0%Au/In2O3 sensor also displayed outstanding selectivity and long-term stability.There are two main reasons for the enhanced C2H5OH sensing properties:(i)The unique structure of bamboo-like nano branches,providing sufficient active surfaces to promote gas molecule diffusion,electron capture and surface reactions.(ii)The appropriate loaded Au plays chemical and electronic sensitization role in the gas sensing performances.