Preparation Of The Monolayer,Bilayer,Microspheres MoSe₂ And The Study On Their Electrocatalytic And Photoctalytic Properties

With the rapid development of science and technology,the use of sustainable energy has become the focus of efforts by all countries around the world.The preparation of hydrogen by electrocatalytic hydrogen reaction（HER）is an important way to develop clean and renewable energy.Therefore,it is crucial to develop novel catalyst with low-cost and high-efficiency to exploit the hydrogen energy.At the same time,with the increasing varieties and quantities of military and civilian products,a lot of waste water,waste gas and waste residue are urgently needed to be degraded and removed.Among them,highly toxic aromatic nitro-explosives are difficult to be degraded completely due to their high solubility and stability.Therefore,the key to solve this problem is to effectively utilize solar energy and to develop a low cost,high efficiency and new kind of catalyst which can be recycled and utilized.In this paper,the nanomaterial of MoSe₂,which is a typical transition metal sulfide compound（TMDs）,was fully researched to explore the potential applications in the HER and the degradation of hazardous waste.The growth regulations of its morphology,layer number and structure were investigated to optimize the HER performance of the MoSe₂ monolayer.And the photocatalytic degradation of nitro-aromatic explosives by MoSe₂ microsphere structure was also researched.All these works are contributed to the design of new electrocatalysts and photocatalysts.And the mainly work includes the following aspects:（1）by using CVD method,the high quality monolayer and bilayer MoSe₂ films are prepared through the optimization of the growth temperature,time and flow of gas.The morphology and structure of MoSe₂ materials were characterized by the modern analytical methods such as SEM,XRD,Raman and TEM.The possible growth mechanisms of the monolayer and bilayer MoSe₂ were proposed through the OM and SEM representation of the growth morphology.（2）The MoSe₂ monolayers with triangular and hexagonal morphology were transferred to Au foil electrode and then three electrode systems were set up.The electrocatalytic properties for HER of these two films were compared.The results indicate that the hexagonal snow-like monolayer has lower overpotential and Tafel slope,which shows better electrocatalytic hydrogenation performance.（3）The MoSe₂ monolayer and bilayer were analyzed by the PL spectra.The results showed that due to the molecules spin-orbit coupling interaction of bilayer MoSe₂,the PL spectrum of bilayer MoSe₂ splits into two peaks with a direct band gap and indirect band gap.（4）The 3D microspheres of flower-like MoSe₂ have been successfully synthesized by using the simple hydrothermal method under the high temperature of200℃.The BET test indicates that the ratio of surface area of this material is about33.28 m²/g.The UV diffuse reflection was also measured and the bandgap gap is about 1.78 eV.（5）For the first time,the MoSe₂ microsphere with 3D flower-like morphology was used as a catalyst to explore the degradation ability of the nitro compound such as nitrobenzene（NB）,p-nitrophenol（PNP）and 2,4-dinitrophenol（2,4-DNP）.The results demonstrated the solutions（40 mg/L）of NB,PNP and 2,4-DNP could be completely degraded by this MoSe₂ microsphere under visible light irradiation with3.5 h,1.5 h and 2.5 h,respectively.The mechanism of the photocatalytic reaction was then investigated in detail,and the photocatalytic degradation process was found to follow the pseudo-first-order kinetics.