Synthesis And Properties Of Polycrystalline Bismuth-based Oxide

Flower Bi₂O₂CO₃ nanomaterials were synthesized by simple water-thermal method,and obtained three Bi₂O₃ polymorphs（α-Bi₂O₃、β-Bi₂O₃andγ-Bi₂O₃）by changing different calcination temperature and cooling rate.The optimal formation conditions for floral Bi₂O₂CO₃precursors were explored in detail by varying the reaction time,reaction temperature,citrate quantity,and the amount of ammonia.Then,the photocatalytic and aerodynamic properties of the prepared Bi₂O₂CO₃ and polycrystalline Bi₂O₃ samples were studied,and the results are as follows.（1）Photocatalytic performance study.Photocatalytic degradation experiments of four different dyes with the same concentration（10 mg/L）were performed using Rhodamine B（Rh B）,Methylene Blue（MB）,Methyl Orange（MO）,and Congo Red（CR）as pollutant templates using Bi₂O₂CO₃ and polycrystalline Bi₂O₃ samples.Experimental results show thatβ-Bi₂O₃ has excellent photocatalytic properties and photocatalytic selectivity.The cycle experiments show thatβ-Bi₂O₃ has good optical stability and recyclability.Finally,the determination of active species against different dyes was explored by capture experiments.（2）Gas-sensing performance.The experimental study on gas selectivity and temperature selectivity were conducted for the prepared Bi₂O₂CO₃ and polycrystalline Bi₂O₃ samples.The results show that theβ-Bi₂O₃ device has good gas sensing performance for 100 ppm acetone gas at an operating temperature of 250℃.In a wide range of acetone concentration detection,theβ-Bi₂O₃ sensor can detect gas in the range of 5-500 ppm.When the sample was exposed to100 ppm acetone gas,the response time was less than 1 s,and the recovery time was 9 s.Simultaneousβ-Bi₂O₃ has excellent stability and reproducibility for 100 ppm acetone gas.The experimental results show the great potential value of the preparedβ-Bi₂O₃ nanomaterials in the application of acetone gas sensor.Finally,the basic characterization of the synthetic WO₃ is performed for the experimental results of the previous exploration.The photocatalytic and aerodynamic properties of WO₃ were also preliminarily investigated.The results show that WO₃ has some degradation capacity for Rh B,MB and CR.And at an operating temperature of 180℃,the minimum detection limit of NO₂ reaches 10 ppb.