| Semiconductor photocatalysis technology has the potential to be one of the valid approaches for improving environmental and energy concerns,which attributed to the advantages of recycle utilization and non-secondary pollution.Importantly,the fabrication of new high-efficiency visible-light-driven photocatalysts have become the research hotspots in the field of photocatalysis research.Bi2MoO6 is an active member of the Aurivillius oxide family that has attracted increasing attention because of the unique photoelectric properties and visible light response.However,its application remains limited by the limited visible-light response that is only less than 500 nm,and the high recombination rate of photogenerated electron-hole pairs in photocatalytic processes,which resulted in poor quantum efficiency.In this subject research,Bi2MoO6 was chosen as the host material.In order to enhance the visible-light photocatalytic performance of Bi2MoO6 and built a new system to achieve the high-efficiency visible-light-driven photocatalytic degradation of organic pollutions,one or more lanthanide ions have been introduced into this host material to adjust the band structures of photocatalyst and then build the crystal defects&redox centers to trap the photo-generated electrons.On this basis,it can be received the new higher-efficiency visible-light-driven photocatalysts by additionally introducing the transition metal ions of W6+ and noble metal of Pt to further modify the Bi2MoO6 catalyst doped with lanthanide ions.The research results are as follows.(I)Tb or Lu single-doped Bi2MoO6 catalyst with high-efficiency photocatalytic performance were successfully synthesized using a hydrothermal method.Meanwhile,the mechanism about the enhanced photocatalytic performance of these catalysts have been also explored preliminarily.1)In the study of Lu-doped Bi2MoO6 photocatalyst,the results revealed that the oxygen vacancies were formed in the lattice of Lu-doped Bi2MoO6;the formed oxygen vacancies played a role in improving charge separation and enhancing light absorption,which resulted in enhancing the photocatalytic degradation rates of RhB and phenol.2)In the study of Tb-doped Bi2MoO6 photocatalyst,the doping of appropriate Tb can not only broaden the visible light response of Bi2MoO6,but also build the Tb4+/Tb3+ redox centers in the lattice of Tb-doped Bi2MoO6;these redox centers can greatly promote the separation of charge carriers by trapping&releasing photo-generated electrons,and resulted in enhancing photocatalytic performance.(?)Based on the lanthanide ions single-doped Bi2MoO6,the mechanism about the enhanced photocatalytic performance of Tb/Eu co-doped Bi2MoO6 has been further investigated.The results implied that the formed Tb-Eu redox cycles by doping of two multivalence lanthanide ions can greatly depress the recombination of electron-hole pairs.Subsequently,the photocatalytic performance of various Lna/Lnb co-doped Bi2MoO6 were also discussed.The results revealed that the relevant Ln13+ 4f7+x/Ln23+ 4f7-x(Ln1/Ln2 = Tb/Eu,Dy/Sm,Er/Nd;x=1,2,4)co-doped Bi2MoO6 samples shows higher photocatalytic activities,which attributed to longer lasting electrons-transferring was occurred in heterodinuclear ions as comparison to that of mononuclear ions.The heterodinuclear redox couple engineering by co-doping of Ln1/Ln2 ions in BMO not only proposes a new conjecture about the complementary distribution between the 4forbital electrons of Lni and Ln2 ions,but also provides a novel strategy to fabricate high-efficiency photocatalysts by selecting appropriate Lni/Ln2 redox couple.(?)Combining with the characteristic action mechanisms of single and double doping,also,the photocatalytic mechanism of three lanthanide ions doped Bi2MoO6 photocatalyst have been synthetically discussed.The results indicated that the introduction of Gd3+1 Er3+ and Lu3+ ions mainly contributed to producing strongly oxidizing ·OH radicals to boost the oxidation ability by Gd3+ redox centers,improving the light absorption to generate more photogenerated carriers by Er3+ up-conversion centers,and promoting the separation of charge carriers to produce more effective active species by forming oxygen vacancies,respectively.All of the three different action mechanisms contributed to enhancing the photocatalytic performance of Bi2MoO6 for degrading organics.The Gd/Er/Lu-triple-doped Bi2MoO6 will serve as a basis for the development of a novel strategy to synergistically enhance the performance of photocatalysts.(?)Based on the lanthanide ions of Gd3+ doped Bi2MoO6 photocatalyst,Gd/Pt co-modified and Gd/W co-doped Bi2MoO6 photocatalyst with high-efficiency visible-light-driven photocatalytic performance were successfully fabricated.The effect rules of doped ions and loaded noble metal on the crystal structures of Bi2MoO6 and the separation&transfer of charge carriers were also insightfully discussed.1)In the study of Gd/Pt co-modified Bi2MoO6 photocatalyst,the results indicated that the ·OH radicals can be formed by doping of Gd3+ ions,and the addition of Pt was conducive to the producing of more ·O2-and ·OH radicals;the congregate introduction of Gd3+ ions and Pt nanoparticles would provide a new strategy to enhance the activity of photocatalyst.2)In the study of Gd/W co-doped Bi2MoO6 photocatalyst,the results indicated that the abundant oxygen vacancies were generated in the crystalline Bi2MoO6 after introducing W6+ ions,and these vacancies adsorbed the extensive O2 molecules;the new hydroxyl radicals can be generated by introducing Gd3+ ions,while the introducing of W6+ ions contributed to enhancing the productivity of ·O2-radicals;these two species together promoted the separation and transfer of electron-hole pairs,ultimately resulted in enhancing photocatalytic performance. |
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