Controllable Preparation Of Spherical Molybdenum Disulfide Micro-nano Hierarchical Structures And Their Photocatalytic Properties

Two-dimensional nanostructured transition metal sulfides?2D TMD?have received intensive research interest as an important family of functional materials in recent years.Especially,as a well-known 2D TMD material,molybdenum disulfide?MoS₂?has excellent intriguing properties for applications in myriad environmental applications such as removal of contaminants,photocatalytic oxidation,and sensing.However,controlled the morphology,structure,size and number of layers of MoS₂ have also been proven to be difficult in practical applications.In our work,two kinds of MoS₂ micro-nano hierarchical structures are synthesized by hydrothermal methods.And the evolution of samples with unique structures has been explored.The superior photochemical properties of yolk-shell/hollow MoS₂ micro/nanomaterials in degrading organic pollutants have been confirmed.The main research results are as follows:[1]The monodispersed yolk-shelled molybdenum disulfide microspheres have been synthesized via a facile and economical hydrothermal method with the assistance of surfactant?polyethylene-polypropylene glycol?P123??.Ostwald ripening is the main formation mechanism for the yolk-shelled structure.The photocatalytic activity of the sample is evaluated by monitoring the photodegradation of rhodamine B?RhB?under white light illumination?500 W xenon lamp?with the assistance of hydrogen peroxide?H₂O₂?.Results indicated that the yolk-shelled microspheres display excellent photocatalytic activity and recycling stability.The photocatalytic degradation rate of yolk-shelled MoS₂ microspheres was achieved 97.6%at only 30 min,which is much higher than those of MoS₂ particles synthesized without P123,MoS₂ solid microspheres,and commercial MoS₂?54.7%,4.6%and 9.6%at 30 min,respectively?.The reaction rate constant?k?of the yolk-shelled microspheres for the photodegradation of RhB is 1.58,92.97 and 107.21 times faster than that of MoS₂particles,MoS₂ solid microspheres and commercial MoS₂.Such a highly desired yolk-shelled structure enables higher multiple light reflections and scattering between the outer spherical shell and the interior core compared with MoS₂ particles,MoS₂solid microspheres and commercial MoS₂,to provide a more efficient way in enhancing light-harvesting efficiency.[2]Monodispersed hierarchical hollow MoS₂ microspheres have been prepared via a facile and economical hydrothermal method with the assistance of surfactant?polyethylene-polypropylene glycol,F68?).The unusual design displays three important features:large specific surface area,strong light absorption,and rich catalytic active sites.The specific surface area of the hierarchical hollow MoS₂microspheres is 21.75 m²g^-1,which is higher than that of MoS₂ particles(4.05 m²g^-1)and commercial MoS₂(2.84 m²g^-1).Meanwhile,the hierarchical hollow MoS₂microspheres possess strong light absorption around a broadband wavelength from200 nm to 800 nm.Furthermore,the ordered MoS₂ nanosheets which assemble to the outer surface of the hierarchical hollow MoS₂ microspheres display rich catalytic active sites,which are beneficial in promoting the fast transport of charge carriers during the process of photocatalytic reaction.As a result,the photodegradation activity test demonstrates that the hierarchical hollow MoS₂ microspheres exhibit excellent photocatalytic activity and recycling stability.The reaction rate constant of the hierarchical hollow MoS₂ microspheres for the photodegradation of RhB is 25.32and 18.18 times faster than that of MoS₂ particles and commercial MoS₂,respectively.