The Modification And Properties Study Of CuInS₂ Class Ternary Chalcogenide Semiconductor Photocatalysis Materials

Pharmaceutical and Personal Care Products are a kind of new environmental pollutant,with the characteristics of toxicity,persistence,bioaccumulation and biodegradation and so on.They enter the water environment through the way of the use of veterinary medicine,human medicine,drug production waste,and cosmetics and so on,which brings hidden trouble to the safety of human health and terrible influence to the ecological system.Therefore,it is very important to remove the organic pollutants in the wastewater before the wastewater is discharged to the environment.Semiconductor photocatalytic oxidation technology is one of the most promising and sustainable technologies for wastewater treatment,however,there are still many problems in its practical application.Therefore,to fullly use of solar energy and improve photocatalytic activity,it is viatal importance to develop new visible-light-responsive semiconductor photocatalysts.The copper indium disulfide?CuIn S₂?is an important ternary semiconductor with band gap of 1.53 eV and a layer absorption coefficient of about 10^-5cm^-1,there are rare studies on the photocatalytic degradation behavior of CuInS₂.In recent years,in order to improve its photocatalytic activity,the preparation and application of CuInS₂ based photocatalyst has attracted more and more researchers'attention.In this paper,CuInS₂ semiconductor nanocrystals were synthesized by regulating the ratio of Cu/In viaing a hot solvent method.Meanwhile,the efficiency of photocatalytic degradation of 2-nitrophenol?2-NP?and the removal efficiency of COD in the real wastewater were investigated.At the same time,we synthesized the rGO/CuInS₂ composite photocatalyst,further improving the photocatalytic efficiency of photodegradation 2-NP and stimulating its application in the real pharmaceutical wastewater.In addition,the formation of heterojunction with CdS semiconductors makes it a great improvement in the photocatalytic degradation of tetracycline.The work of the paper are summarized in detail as follows:?1?CuInS₂ semiconductor were synthesized by regulating Cu/In molar ratio viaing a hot solvothermal method.Different Cu/In molar ratio in reaction system had significant influence on the BET surface area,charge separation and photocatalytic activity of CuInS₂.The CuInS₂ with optimal Cu/In ratio of 1:1.5 exhibits the most efficient charge separation and transfer,leading to the highest photocatalytic activity.The mineralization efficiency to pharmaceutical wastewater by CuInS₂?Cu:In=1:1.5?was 67.5%in 6 hours,and CuInS₂?Cu:In=1:1.5?exhibited high stability.?2?We prepared the rGO/CuIn S₂ composite by a simple one-step solvothermal method.The photocatalytic activity of rGO/CuInS₂ was much higher than that of pure CuInS₂,and was highly dependant on rGO amount.The 1%rGO/CuInS₂ composite demonstrated the highest visible-light photocatalytic activity of 2-nitrophenol removal rate with almost 90%,which was almost two times of pure CuInS₂.Of special significance is that 1%rGO/CuIn S₂ composite can effectively treat real pharmaceutical wastewater with 86.5%chemical oxygen demand?COD?removal efficiency in 11 hours.?3?In this study,CdS/CuInS₂ nano-heterojunctions were fabricated by a facile one-step hydrothermal method,and the molar ratio of CdS to CuInS₂ was optimized.Compared to CuInS₂,?1:0.03?CdS/CuInS₂ heterojunction exhibits 4 times higher visible-light photodegradation TC·HCl in 120 min.Meanwhile,almost 100%of the aqueous Cr?VI?was reduced after 60 min by the?1:0.03?CdS/CuInS₂ heterojunction.Due to the narrowest band gap,the largest BET surface area,the most efficient charge separation,and the synergistic effect between CdS and CuInS₂.Of special significance is that?1:0.03?CdS/CuInS₂ heterojunction can effectively treat real pharmaceutical wastewater with 76.5%COD removal efficiency in 13 hours.Moreover,CdS/CuInS₂ heterojunctions show excellent reusability in five degradation–regeneration cycles.The results indicate that CdS/CuInS₂ has a promising prospect in real pharmaceutical wastewater treatment due to high efficiency and excellent stability.