| In the context of the current energy shortage,the search for alternative new energy has become the goal that people are constantly pursuing.Hydrogen energy as a fuel has the advantage of large calorific value and zero pollution.Therefore,as an emerging technology,photocatalytic hydrogen evolution is crucial to solve the energy crisis that may become more serious in the future.It is imperative to continuously explore and develop photocatalysts with high catalytic performance,cheap,easy to obtain and strong stability.Metal-organic frameworks(MOFs)have been widely used in photocatalytic field as high efficiency catalysts or templates.The highly adjustable skeleton structure and fully exposed metal active sites enable MOFs and their derivatives to continuously exert great catalytic potential.At the same time,synthesis of efficient and high stability CdS composite without doping precious metals has always been a hot spot of the application research on photocatalytic hydrogen production.In this paper,MOFs with excellent properties have been used as templates to derive a series of CdS composites containing sulphide co-catalysts,and their catalytic ability to reduce water under visible light has been studied,and the results are as follows:(1)Mo-MOF has been used as template to combine MoS2 and CdS together effectively.To be specific,Cd2+has been added to form Mo-MOF/CdMoO4 organic-inorganic composite,and CdS@MoS2 sulfides gradually form under the action of organic sulfur source.The photocatalytic hydrogen production rate of CdS@MoS2 is 4.1 mmol·g-1·h-1,which is significantly improved compared with the single-component CdS material.After the characterizations of the appearance structure and photoelectric characteristics of the material,the well catalytic activity is mainly due to the big BET,strong charge transfer efficiency and strong electron conductivity of the material after vulcanization.The specific surface area of 107.7 m2/g indicates that there are more active sites in the photocatalytic process.The combination of MoS2 and CdS changes the energy band position and internal electron transfer characteristics,thus showing high light response and charge separation ability.Therefore,the synergistic effect of sulfides promotes better activity.This design strategy also provides valuable experience for the follow-up work.(2)In order to prepare CdS based materials with high catalytic activity,a method has been designed to convert bimetallic MOF into bisulfide components by vulcanization reaction with high temperature and high pressure.Although NiS is an ideal candidate,it remains a challenge to optimize the combination of NiS and CdS to better improve the photocatalytic hydrogen evolution activity.Herein,a novel CdS@NiS material with well-contacted heterojunction interfaces has been synthesized from vulcanizing bimetallic MOFs that are obtained through an ion exchange strategy.The formation of bimetallic Cd/Ni-MOFs can induce well heterogeneous interfaces between CdS and NiS at nanoscale,which efficiently promotes the separation of photo-generated carriers and boosts electron interface transfer.As a result,the obtained CdS@NiS exhibits a high photocatalytic hydrogen evolution rate of 42.7 mmol·g-l·h-1,and the corresponding apparent quantum yield reaches 13.23%at 450 nm,superior to those obtained using the traditional simple physical mixing methods.This work provides a new reasonable way for designing highly efficient photocatalysts. |
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