Synthesis And Photocatalytic Properties Of Boron-doped Bismuth Vanadate And Its Composites

Semiconductor photocatalysis technology was used to achieve efficient,rapid,and clean degradation of organic pollutants,which is a current research hotspot.Monoclinic BiVO₄（m-BiVO₄）has attracted extensive attention due to its non-toxic,low-cost,narrow bandgap,and high photocatalytic activity,but its photocatalytic performance still needs to be improved.In this paper,leaf-like B-doped m-BiVO₄ with highly exposed active（010）facets and its composite with Mo S₂ were successfully synthesized through a solvothermal method.The photocatalytic performance of the samples was investigated by photodegradation of chlortetracycline hydrochloride（CTC-HCl）,oxytetracycline（OTC）,tetracycline（TC）and tetracycline hydrochloride（TCN）solutions,and agar plate colony counting method.And their photocatalytic mechanism was explored.The main research work is as follows:（1）Preparation of B-doped BiVO₄.B-doped BiVO₄ with different doping amounts and highly exposed active（010）facets were synthesized through a solvothermal method,using H₃BO₃ and Na₂B₄O₇·10H₂O as boron sources,respectively.The phase structure,morphology,and microstructure of the samples were characterized by XRD,SEM,TEM,etc.The samples appear leaf-like morphology constructed by orderly attached small plate-like nanoparticles.The addition of an appropriate amount of B promotes the exposure of the（010）facets,and the photogenerated electrons are accumulated on the（010）facets,which facilitates the separation of the photogenerated carriers.The bandgap of samples before and after doping has little change,and the BET surface area of each sample is not much different and small.XPS shows that a part of B³⁺ions enters the lattice and replaces the position of the O to form the B-Bi-O structure,and then forms a V⁴⁺/O_V defect state,which reduces the charge transfer resistance,improves the separation efficiency of photogenerated carriers,and can generate more·O₂^-and·OH.（2）Photocatalytic performance of B-doped BiVO₄.B-doping significantly improves the photocatalytic activity of BiVO₄,and the photocatalytic activity of B-doped BiVO₄ synthesized with borax as the boron source is better.The sample prepared at the initial molar ratio of B to Bi is 0.05 exhibits the highest photocatalytic performance,and the degradation rates of CTC-HCl,OTC,TC,and TCN are 81.72%,83.88%,67.94%,and 79.80%,respectively after 150 min illumination.The antibacterial rates of E.coli and S.aureus were 98.28%and 96.17%,respectively.（3）Preparation and photocatalytic performance of B-doped BiVO₄ and Mo S₂ composite.B-BiVO₄-Mo S₂ with different BiVO₄/Mo S₂ mass ratios were synthesized through a solvothermal method.The phase structure,morphology,and microstructure of the samples were characterized by XRD,SEM,TEM,etc.The XRD patterns retain the characteristic that the（040）peak is the main diffraction peak,and the composite material appears needle-like aggregates and leaf-like morphology.After recombination,the light absorption intensity significantly increases,and there is a strong response in the visible light region.The photocatalytic activity of the composite is significantly higher than that of pure Mo S₂ nanoflowers and B-doped BiVO₄.The sample prepared with a BiVO₄/Mo S₂ mass ratio of 15 has the highest photocatalytic performance,and the degradation of TC is 85.44%after 120 min of illumination.The composite material forms a direct Z-scheme heterojunction structure,which can effectively inhibit the recombination of photo-generated electrons and holes,accelerate charge transfer,extend the life of photo-generated carriers,and improve photocatalytic performance.