Metal-Organic Frameworks Templated Synthesis Of Molybdenum Disulfide-based Hybrid Nanomaterials And Their Photocatalytic Water Spliting For Hydrogen Evolution

The application of semiconductor in catalyzing water decomposition has received widespread attention since Fujishima and Honda et al reported the application of TiO₂ in photocatalytic hydrogen production for the first time in 1972,and the synthesis of catalysts is significant especially.Metal organic framework（MOF）structure as a template for synthesizingof catalytic materials gradually shows a number of advantages which can obtain samples with contrallable morphology,uniform pores and big surface area.In recent years,due to the high catalytic activity and low cost and competitive,molybdenum disulfide and other materials quickly become a research focus.In order to solve the problem that the molybdenum disulfide-based material is too large and the active site is not enough,this thesis choose two classical MOFs structures as templates to synthesize molybdenum disulfide-based composites and apply them to photo-and electrocatalytic hydrogen evolution research.It is proved that MOFs can realize the controllable synthesis of molybdenum disulfide composite catalytic materials as template,and provide the theoretical basis and research foundation for research into the production of such materials.The specific work contents are as follows:（1）The three-dimensional MoS₂@TiO₂ composite photocatalyst was prepared by using NH₂-MIL-125（Ti）as precursors and reacted with thiourea and sodium molybdate at high temperature.And a more comprehensive study was carried out on its crystal structure,element valence,microstructure,optical properties and electrical properties.Furthermore,a three-component photocatalytic system was established in the presence of sacrificial agent triethanolamine（TEOA）and photosensitizer fluorescein（Fl）,and the photocatalytic hydrogen production performance of the catalyst was investigated.In addition,the factors influencing the hydrogen production activity of the system were screened.It was proved that in the condition that the photosensitizer was 10 vol% TEOA,acetone / water = 1: 3,pH = 11,MoS₂ loading 14.6 wt%,hydrogen production rate can reach the highest 10046 μmol h^-1 g^-1.At the same time,the stability and electron transport of the hydrogen-producing system are discussed in detail.The results of hydrogen production cycle experiments show that the composite photocatalyst has good hydrogen production stability,and after three cycles in 33 hours,the hydrogen efficiency has no significant change.A series of steady-state fluorescence tests and fluorescence lifetime tests had proved that under the excitation of visible light,the photosensitizer transferred electron to the catalyst through reduction quenching to finish the catalytic reaction of hydrogen production.（2）Using a metal（Ni,Zn,Cu）doped ZIF-67（Co）as the precursor and reacting with thiourea,sodium molybdate at high temperatures to obtaine three-dimensional composite structure with large specific surface area.And a series of characterization were developed for Cu_0.9Co_2.1S₄@MoS₂ catalyst.The catalyst can stably catalyze in pure water,which avoids the secondary contamination caused by the use of organic solvents.Based on the screening of hydrogen production conditions,it was proved that the hydrogen production capacity of the catalytic system can reach 19058 μmol h^-1 g^-1 under the condition of the composite photocatalyst doped with copper（Cu : Co = 3 : 7）,molybdenum disulfide loading was 25.8 wt%,TEOA content of 5.3 vol% and pH = 13.In addition,this thesis not only proves the transmission of electrons,but validates the successful combination of synthetic catalysts from the perspective of photocurrent response experiments and electrochemical impedance spectroscopy.