Synthesis And Properties Of α-MoO₃ Nanomaterials

In this paper,two morphologies of orthogonal molybdenum oxide（α-MoO₃）materials are synthesized by a simple hydrothermal method,which areα-MoO₃ flower-like andα-MoO₃nanobelts.Theα-MoO₃ flower-like have good growth and clear shape.The obtainedα-MoO₃ nanobelts have good structure and good dispersibility.By changing the temperature,time,the amount of aqueous hydrogen peroxide solution and the amount of deionized water,The influence on the microstructure ofα-MoO₃ materials have been discussed and analyzed.In the process of synthesizingα-MoO₃ material,When molybdenum acetylacetonate is used as the molybdenum source,initial nanoparticles are formed by conventional nucleation firstly.As the reaction proceeds,these nanoparticles are dissolved and recrystallized to form nanobelts,and then the directional attachment of nanobelts promote the formation of loose flower-like structures.At last,through the further directional attachment and self-assembly process,the compactα-MoO₃ flower-like structure is gradually formed.when molybdenum trichloride is used as the molybdenum source,α-MoO₃ crystal nuclei are first formed at the nucleation stage,and then theα-MoO₃ crystal nucleus arrays are formed through the self-assembly process.And finally the monodisperseα-MoO₃ nanobelts are obtained through the Ostwald ripening process.Subsequently,the gas sensing properties and photocatalytic properties ofα-MoO₃ flower-like andα-MoO₃nanobelts have been studied in this thesis.The research contents are as follows:（1）Gas sensing performance:The sensors based onα-MoO₃ flower-like andα-MoO₃nanobelts are tested for gas response at different concentrations at 200°C.In the range of 1-10 ppm NO₂ concentration,the results show that response time of the sensor based onα-MoO₃ flower is slightly greater than 120 s,recovery time of the sensor is less than 136 s,and the minimum detection limit of NO₂ concentration is 3 ppm.In addition,the results show that response time of the sensor based onα-MoO₃ nanobelts is less than 120 s,recovery time of the sensor is less than 100 s,and the minimum detection limit of NO₂concentration is 1 ppm.Moreover,the sensors based onα-MoO₃ flower-like andα-MoO₃nanobelts have good stability.（2）Photocatalytic performance:Four different dyes,including Rhodamine B（Rh B）,Methylene Blue（MB）,Congo Red（CR）and Methyl Orange（MO）,are degraded at the same concentration（10 mg/L）usingα-MoO₃ flower-like andα-MoO₃ nanobelts respectively.The results of usingα-MoO₃ flower-like as photocatalysts to degrade dyes under visible light show the degradation rate of Rh B reached 93%within 140 min and the degradation rate of MB reached 94%within 140 min.The results of usingα-MoO₃nanobelts as photocatalysts to degrade dyes under visible light show the degradation rate of Rh B reaches 95%within 120 min and the degradation rate of MB reaches 97%within 60min.In addition,The adsorption time ofα-MoO₃ flower-like andα-MoO₃ nanobelts for CR did not exceed 10 min.This result indicates thatα-MoO₃ nanobelts have more prominent photocatalytic performance thanα-MoO₃ flower-like.In addition,α-MoO₃ nanobelts have been used as catalysts to carry out catalytic degradation cycle experiments.The results find thatα-MoO₃ nanobelts have good stability.