Preparation Of Anti-symmetric Dual Z-scheme ZnIn₂S₄/Er³⁺:Y₃Al₅O₁₂@ZnTiO₃/CaIn₂S₄ Photocatalyst For Degradation Of Acid Orange ? With Simultaneous Hydrogen E

As a green and environmentally-friendly treatment technology with high efficiency,low cost and non-secondary pollution,photocatalysis has widely application potential in purifying sewage and producing clean energy.Hydrogen production from wastewater by photocatalysis,which the organic contaminants from wastewater are served as sacrificial agents,can achieve the degradation of organic pollutants with simoutanous hydrogen generation.It not only solves water pollution problem,but also produces renewable energy to alleviate the shortage of energy.The wide band-gap semiconductor photocatalysts have good redox properties and can simultaneously produce the reaction of photocatalytic degradation of organic contaminants and hydrogen production.However,due to its wider bandgap,it can only be excited by high-energy ultraviolet light,which the utilization range of solar spectrum is narrow.Moreover,the photo-generated electron-hole pairs are easily recombined,which reduces the quantum efficiency.Thus,in order to improve these two cases,the study selected two narrow bandgap semiconductor photocatalysts?ZnIn₂S₄ and CaIn₂S₄?and a wide bandgap semiconductor photocatalyst?ZnTiO₃?to form a dual Z-scheme photocatalytic system.This not only broadens the response range of sunlight,but also promotes the separation of photo-induced electrons and holes and enhances redox capability.In addition,the upconversion luminescence agent Er³⁺:Y₃Al₅O₁₂ is coated by the wide bandgap semiconductor photocatalyst,which can convert visible light into ultraviolet light to provid more ultraviolet light to excite the wide bandgap semiconductor photocatalyst?ZnTiO₃?,thereby improving the utilization of sunlight.Therefore,the designed and new photocatalytic system can enhance the photocatalytic performance,which is beneficial to achieve more efficient degradation of organic pollutants with simultaneous hydrogen production.In the study,the anti-symmetric dual Z-scheme ZnIn₂S₄/Er³⁺:Y₃Al₅O₁₂@ZnTiO₃/CaIn₂S₄ photocatalyst was prepared by isoelectric point and calcination methods.The elemental composition,surface morphology and crystal structure of the prepared samples were analyzed by the methods of X-ray diffractometer?XRD?,scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,energy dispersive X-ray spectroscopy?EDX?,X-ray photoelectron spectroscopy?XPS?,UV-vis diffuse reflectance spectra?UV-vis DRS?,fourier transform infrared spectra?FT-IR?,and so on.Photoluminescence spectroscopy?PL?was utilized to study the recombination of photo-generated electrons and holes,and the electrochemical impedance spectroscopy and transient photocurrent response were used to further verify the recombination of photo-generated electrons and hole.In this study,the photocatalytic activity of the anti-symmetric dual Z-scheme ZnIn₂S₄/Er³⁺:Y₃Al₅O₁₂@ZnTiO₃/CaIn₂S₄ photocatalyst is estimated via the experiment of degradation of acid orange ? with simultaneous hydrogen evolution under simulated sunlight irradiation,which acid orange ? is used as a target organic contaminant.The results of the research show that the anti-symmetric dual Z-scheme ZnIn₂S₄/Er³⁺:Y₃Al₅O₁₂@ZnTiO₃/CaIn₂S₄ photocatalyst has higher photocatalytic activity in the reaction of degradation of acid orange ? with simultaneous hydrogen production.It can be attributed to the enlarged photoresponse range,an increased reduction surface and enhanced separation efficiency of photo-generated carriers.Furthermore,the cyclic experiments show that it has high photocatalytic activity and stability.In summary,the work successfully designed an anti-symmetric dual Z-scheme ZnIn₂S₄/Er³⁺:Y₃Al₅O₁₂@ZnTiO₃/CaIn₂S₄ composite photocatalyst,which is effective and simulated solar light driven,for photocatalytic degradation of organic contaminants with simultaneous hydrogen production.The research will offer a promising way to effectively solve water pollution problems and efficiently produce clean energy.