| Perovskite oxides and layered perovskite oxides with different compositional and constituent elements,which are promising materials due to the high activity,structural flexibility,better stability and lower cost.In the past years,various of perovskite oxides and layered perovskite oxides have been developed for environmental remediation and solar energy applications,including degradation of organic pollutions,reduction of heavy metal ions and water splitting under visible light irradiation.Thus,exploiting the novel,high-efficient and environment-friendly photocatalysts are urgent and necessary for the long-term development.Structural modification has a strong impact on their optical and electronic properties through metal co-catalysts decoration and other semiconductors complexes.Various methods have been paid to the modification of perovskite oxides and layered perovskite oxides,including ion doping,cocatalyst loading and constructing heterojunctions.H2SrTa2O7 as a typical Ruddlesden-Popper phase layered perovskite(A2'An-1BnO3n+1),which are considered as a promising UV-light photocatalysts with wide band gaps(3.90 eV).However,extensive application of H2SrTa2O7 photocatalysts is seriously hindered ascribe to the limited utilization of solar energy and the low separation and transfer efficiency of photogenerated charge,leading to the low photocatalytic activity.In this regard,the development of H2SrTa2O7-based photocatalysts with outstanding visible light photocatalytic activity is still urgent and necessary.In these regards,we aim to design better perovskite photocatalysts with efficient light harvesting and high separation efficiency of charge carrier.Herein,the following sections illustrate a central theme of structural modification of H2SrTa2O7-based catalysis.In addition,the preparation,characterization and the catalytic performance of H2SrTa2O7-based catalysis are also discussed.The research consists of three aspects:1.H2SrTa2O7 was prepared by ion-exchanged by K2SrTa2O7(Ruddlesden-Popper phase layered perovskite)using HNO3 aqueous solution.Amine groups can be easily introduced into the interlayer space of H2SrTa2O7 due to the weak connection of van der Walls force.D-glucopyranose was intercalated onto the interlayer surface of H2SrTa2O7 to replace the n-octylamine molecule through hydrothermal reaction.The organic functional groups of D-glucopyranose can be confirmed by 13C CP/MAS NMR and IR spectra.Ag nanoparticles with ultrasmall sizes were assemled on the H2SrTa2O7 nanosheets through silver mirror reaction.The SEM and TEM shows Ag nanoparticles homogenously dispersed on the surface of H2SrTa2O7 nanosheets with average diameter of 5.18±1.20 nm.Furthermore,C8N-H2SrTa2O7,Glu-H2SrTa2O7 and Ag/H2SrTa2O7 shows the remarkable feature of similar lamellar morphologies.The Ag/H2SrTa2O7 composite exhibits remarkably high and stable catalytic activities toward the reduction of 4-NP and MO solutions with 100%conversion and in the presence of NaBH4 within 4 min and 10 s,respectively.2.We first synthesized a high efficient ternary H2SrTa2O7/g-C3N4/Ag3PO4 heterojunction based on the binary composite of H2SrTa2O7/g-C3N4-60 wt%system.H2SrTa2O7/g-C3N4/Ag3PO4 heterojunction shows enhanced photodegradation of organic pollutions(methyl orange,rhodamine B,methylene blue,phenol and 2,4-dichlorophenol)compared to pristine H2SrTa2O7,g-C3N4 and H2SrTa2O7/g-C3N4-60 wt%.Take the photoreduction of MO as a model,the pristine g-C3N4,H2SrTa2O7 and binary composite of H2SrTa2O7/g-C3N4-60 wt%represent poor photocatalytic activity with only 20.3%,22.7%and 26.2%of MO was degraded under visible light irradiation for 30 min,respectively.Whereas,H2SrTa2O7/g-C3N4/Ag3PO4 heterojunction possess a superior photocatalytic activity of 100%MO was completely degraded within 8 min.By means of photoluminescence spectroscopy,impedance spectroscopy,ESR measurements and active species trapping tests,we proposed a plausible photocatalytic mechanism for photocatalysis process of the H2SrTa2O7/g-C3N4/Ag3PO4 ternary photocatalyst.The improved photocatalytic performance could be ascribe to prominently promoted charge separation efficiency,the matched band-edge positions,the extension of the absorption range and the synergistic effect among H2SrTa2O7,g-C3N4 and Ag3PO4.3.On the basis of the obtained binary composite of H2SrTa20 7/g-C3N4-60 wt%,a three-component system,Ag/H2SrTa2O7/g-C3N4,has been successfully prepared by photo-deposition.The TEM images clearly shows the tiny Ag nanoparticles were uniformly decorated on the surface of H2SrTa2O7 and g-C3N4.The enhanced photocatalytic activity of reduction of aqueous Cr(?)was achieved for Ag/H2SrTa2O7/g-C3N4,which is higher than the any components of g-C3N4,H2SrTa2O7 and H2SrTa2O7/g-C3N4 due to the well light absorption efficiency and electron-hole pair separation.Herein,it confirmed the Ag particles between H2SrTa2O7 and g-C3N4 act as an effective media for the transfer of interfacial electron in the composite and absorbing visible light based on the surface plasmon resonance(SPR). |
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