Construction Of MoO₃-based Heterojunction And It’s Photocatalytic Activity Enhancement Mechanism

Semiconductor photocatalysis material becomes one of the hottest and widely studied field,because it has the high photocatalytic activity,low cost and environmentally friendly.MoO₃ was considered an important semiconductor material,it has extensively applied and studied in different fields due to its unique structure,excellent optical and electrical properties and abundant storage.In the field of photocatalysis,MoO₃ performs the higher photocatalytic activity.However,it was mentioned that Mo possess a stronger electronegatity,which is not favorable to transportation ang migration of photogenerated electron,leading to the low quantum yield.Here,it becomes urgent to promote the separation of photogenic electron and hole,improving its photocatalytic activity,so that it can be widely used.In this study,we have obtained some heterojunction photocatalysts with good performance by the modification of one dimension（1D）α-MoO₃ and h-MoO₃,the detailed process is describe as follow:First,the novel Z-scheme photocatalysts AgI/Ag/α-MoO₃ were prepared by a facile hydrothermal deposition and photoreduction methods.X-Ray Diffraction（XRD）and X-ray Photoelectron Spectroscopy（XPS）were empolyed to characterized compositions and crystalline structures,Scanning/Transmission Electron Microscope（SEM/TEM）were empolyed to characterized morphologies,UV-Vis Diffuse Reflectance Spectroscopy（UV-Vis-DRS）,Photoluminescence Spectroscopy（PL）and Electrochemical Impedance Spectroscopy（EIS）were empolyed to characterized optoelectronic properties.The degradation of thiophene in model fuel was tested to investigate the photocatalytic activity and stability of a series of as-made composites.The results indicated that the AgI,Ag modified the surface ofα-MoO₃ is beneficial to the separation of photo-generation electron and hole pairs,significantly improved its photocatalytic activity.AAM-35heterojunction has a highest photocatalytic activity which removal efficiency for thiophene reached up to 97.5%under visible light irradiation for 120 min.Even after 4cycle,the yied of desulfurization rate is still above 86%.Second,the heterojunction AgI/h-MoO₃ catalysts were obtained by hydrothermal and deposition method.XRD and XPS were empolyed to characterized compositions and crystalline structures,SEM were empolyed to characterized morphologies,UV-Vis-DRS,PL and EIS were empolyed to characterized optoelectronic properties.The photocatalytic activity and stability of AgI/h-MoO₃ was investigated by using FCC gasoline as a probe in n-octane solution of thiophene.The results indicated that the AgI loading the surface of h-MoO₃ is favorable to the separation of photo-generation electron and hole pairs,significantly improve its photocatalytic activity.AgI/h-MoO₃-18 heterojunction has a highest photocatalytic activity which removal efficiency for thiophene reached up to98.0%under visible light irradiation for 120 min and the removal efficiency is still remain 83%after recycling used 5 times.Using XRD,XPS and uv-vis-DRS,it is revealed that AgI/h-MoO₃ generates a small amount of metal Ag after illumination,so that its structure is transferred to Z-scheme AgI/Ag/h-MoO₃ heterojunction.Third,the heterojunction photocatalyst Fe₂O₃/α-MoO₃ was obtained by a facile hydrothermal method and precipitation-deposition method.XRD and XPS were employed to characterise compositions and crystalline structures,SEM-EDS and STEM-EDX were employed to characterise morphologies,UV-Vis-DRS were employed to characterise optical properties.The photocatalytic activity of Fe₂O₃/α-MoO₃ was investigated in RhB solution and the model FCC gasoline solution.The results indicated that the Fe₂O₃ modified the surface ofα-MoO₃ is beneficial to the separation of photo-generation electron and hole pairs,significantly improved its photocatalytic activity.The removal efficiency for RhB 1wt%Fe₂O₃/α-MoO₃ heterojunction could be reached 99%under visible light irradiation for 40 min,and for thiophene reached up to83.2%under visible light irradiation for 240 min.