Preparation And Photocatalytic Performance Of Metal Sulfide/Carbon Nitride Composites

Photocatalytic technology has received substantially attention as it can make use of solar energy for wastewater degradation.Particularly,the cost,degradation performance and lifetime of photocatalyst are significant reference during the actual application.Nevertheless,traditional photocatalyst,such as anatase TiO₂,can only absorb the UV part?about 5%?of the total solar spectrum,restricting its industrial application.Owing to their availability,low cost and superior visible-light absorption,metal sulfides have been extensively studied in the field of material and catalysis.However,most metal sulfides suffer from the low photostability and short lifetime of carriers.In order to conquer the drawbacks in metal sulfides,some modification approaches,including altering its morphology and coupling with g-C₃N₄,were developed to efficiently promote the separation and transportation of electron-hole pairs.Additionally,the formed heterojunction is beneficial for the photostability and utilization rate of solar,thus enhancing the photocatalytic performance.The main points are presented as follows:?1?The Bi₂S₃/g-C₃N₄ heterostructured photocatalysts with various Bi₂S₃ contents were synthesized using hydrothermal route and used for the photodegradation of methyl orange?MO?,rhodamine B?RhB?and ciprofloxacin?CIP?.The heterostructure constructed between Bi₂S₃ and g-C₃N₄ could enhance its photostability and separation of electron-hole pairs.Simultaneously,the photocatalytic activity of MO?10 mg·L-1?over Bi₂S₃/g-C₃N₄ was better than pure substance and the physical mixture of g-C₃N₄ and Bi₂S₃.Particularly,the main reactive oxidative species?hole and superoxide radical?could be detected in the MO degradation.?2?NiS₂ nanoparticles had been successfully deposited on g-C₃N₄ nanosheets using a one-pot solvothermal approach and characterized by a variety of instrument.The results suggested the highest photodegradation rate?0.00818 min-1?would be achieved while the mass fraction of NiS₂ was 13.7%.Furthermore,the synergistic effect between them was systematically investigated.The improved photocatalyticperformance of composite was ascribed to the strong visible-light absorption and specific surface area which could facilitate the adsorption of more pollutant molecules and produce more active reaction sites.Meanwhile,the intimate interfacial contact could accelerate the generation,separation and transportation of photoinduced carriers.?3?Unique hollow sphere-like NiS₂ modified by graphite-like carbon nitride were synthesized using a facile template-free,solvothermal approach.NiS₂ hollow microspheres were advantageous for light trapping and enabling the inner surfaces of the photocatalyst to facilitate the adsorption of more pollutant molecules.ESR,TEM,SEM,XPS,PL,EIS,time-resolved fluorescence and transient photocurrent response were utilized to systematically study the radicals,morphology and charge transfer of the obtained composite.An exceptional performance in terms of impressive cyclic stability and excellent photocatalytic efficiency in RhB,MO and CIP degradation was due to the cooperative effects of the hollow sphere-like structure,good light harvesting and novel 3D/2D heterostructure.