The Synthesis And Photoluminescence Properties Of Nano-scale BCNO Phosphors

BCNO phosphor is a typical class of non?rare earth doped luminescence materials,which has great potential applications in white LED,display,and biomedical areas.In this thesis,we successfully synthesized nano?scale BCNO luminescence materials by template method and one step liquid method,respectively.On one hand,we synthesized BCNO QDs（quantum dots）using the template of SBA?15 and realized the applications in chemical sensors,white LED and fingerprint identification.On the other hand,we synthesized the BCNO nanosheets by one?step liquid method and further obtained the BCNO composites through combining BCNO nanosheets with some transition metal oxides,and investigated their properties in photoluminescence,photocatalysis and electrochemistry.BCNO QDs were synthesized by using boric acid,urea and citric acid as raw materials and SBA?15 as a template with reaction temperature of 650°C.The BCNO QDs had the t?BN structure with particle size of 4.5 nm,and they had good dispersibility in aqueous solution.The emission spectra of BCNO QDs were in blue band with the emission peak centered at 440 nm.The emission intensity of BCNO QDs was decreased with adding increased concentration of Cu²⁺or Hg²⁺ions,and had a good linear relationship.BCNO QDs could be used for the detection of specific metal ions with the detection limit as less as10 nM.Moreover,we investigated the influence of Cu²⁺or Hg²⁺on band structure of BCNO by theoretical calculation,and interpreted the reasons of luminescence quenching of BCNO QDs.In addition,the BCNO?Cr⁶⁺mixture can be served as a turn?on fluorescent sensor for detecting the ascorbic acid based on the inner filter effect.BCNO QDs based white LEDs were fabricated by combining BCNO QDs（blue）with fluorescein sodium（green）and rhodamine B（red）,which performed excellent white light properties.Furthermore,the BCNO QDs can also be used for fingerprint identification and organic fluorescent films based on its good dispersion in PVA solution.BCNO nanosheets composites were synthesized with one?step liquid method.Boric acid,melamine and acetate（oxide raw materials）were dissolved in hot glycol and the precursor was sintered at low temperature to obtain BCNO composites.BCNO nanosheets had blue emission and the emission spectra were shifted to longer wavelength with increasing sintering temperature.The PL properties of BCNO nanosheets could be influenced by different transition metaloxides.The intensity of emission spectra of BCNO was weakened by TiO2,and BCNO/TiO2 composite could not only improve the catalytic properties of TiO₂ under ultraviolet light,but also could be used as visible photocatalysts,which has a significant effect in the degradation of Methylene blue（MB）solution.Al2O3addition changed the emission spectra of BCNO nanosheet which appeared a new emission peak of 460 nm from Al2O3:C.ZnO did not change the emission peak position of BCNO nanosheet,and only affected the luminescence intensity.For magnetic Co3O4,it greatly decreased the emission intensity of BCNO nanosheet.However,the BCNO/Co3O4composites had a good electrocatalytic performance,and BCNO nanosheet could significantly improve the oxygen evolution reaction（OER）property of Co3O4,and the optimal overpotential of BCNO/Co3O4 composites was 320 mV,which has potential applications in the field of electrocatalysis.