Controllable Construction And Hydrogen Production Performance Of CdS/2D Ti₃C₂ Composite Photocatalytic Materials

In recent years,global energy shortages and environmental pollution problems have become more prominent.Hydrogen energy is regarded as one of the best energy sources that can solve the above problems because of its high calorific value and combustion without pollution.The use of green and abundant solar energy to catalyze water decomposition to generate hydrogen is an ideal way to obtain hydrogen energy,and the key to this technology lies in the design and preparation of highly efficient semiconductor photocatalytic materials.Although most of the pure phase semiconductors that have been discovered so far can exhibit certain photocatalytic activity,the light absorption of these single-phase semiconductors is narrow,and the electron-hole recombination is serious,which leads to the low efficiency of the material to decompose water to produce hydrogen.Studies have shown that the composite construction of two or more suitable semiconductor materials can effectively increase the light absorption range and enhance the separation efficiency of photogenerated carriers.However,the chemical composition,structure,surface interface properties,and chemical stability of the composite material will significantly affect the photocatalytic performance of the material.Therefore,the development of composite materials with controllable composition,adjustable size,tight interface coupling and chemical stability is the key to obtain efficient photocatalytic materials.The cadmium sulfide?CdS?material has been proven not only to have an energy band structure that matches water decomposition,good visible light response,but also an adjustable low-dimensional nanostructure,making it an ideal material for hydrogen production by photolysis of water.However,such materials have serious photocorrosion and are prone to photogenerated electron-hole pair recombination,which greatly limits their application in photocatalytic hydrogen production.In this paper,CdS with different dimensions is used as the host material,and it is compounded with ultra-thin two-dimensional titanium carbide?Ti₃C₂?nanomaterials with high conductivity.By constructing close heterogeneous interface with control,the photoelectron transport and carrier separation are promoted,the electron-hole composite is reduced,and the photocorrosion of cadmium sulfide is inhibited,so as to improve the photocatalytic hydrogen production performance of CdS materials.The specific research contents are as follows:?1?Using cadmium nitrate as the cadmium source,thiourea as the sulfur source,and titanium carbide as the assembly platform,through the principle of ion exchange and electrostatic self-assembly,the cadmium nitrate and thiourea were adsorbed on the surface of the two-dimensional Ti₃C₂,prepared by solvothermal method 1D CdS/2D Ti₃C₂ nanocomposites.Compared with the 1D CdS nanorods prepared under the same conditions,the photocatalytic performance of the 1D CdS nanorods modified with 2D Ti₃C₂ to decompose hydrogen in water has been significantly improved.The results showed that the Schottky contact formed between the 1D CdS and 2D Ti₃C₂ promotes the transfer of electrons to Ti₃C₂,and the Ti₃C₂ with metal-like conductivity further accelerates the migration of electrons.In addition,the ultra-thin morphological characteristics,good hydrophilicity and full-spectrum absorption characteristics of Ti₃C₂nanosheets synergistically enhanced the photocatalytic hydrogen production performance of CdS nanorods.?2?Considering the influence of morphological structure and nano size on the exposure of photocatalyst reactive sites and the properties of the composite interface,this paper prepared 2D CdS nanosheets with control by changing the cadmium source and sulfur source materials and optimizing the solvothermal conditions,and the use of ion exchange and electrostatic adsorption to realize the in-situ growth of CdS nanosheets on Ti₃C₂ nanosheets,further enhancing the photocatalytic hydrogen production activity of CdS/Ti₃C₂ nanocomposites.Through the analysis of the morphology,structure and photoelectric properties of the 2D CdS nanosheets and their composite materials,it can be seen that the adjustment of the morphology of CdS optimizes the contact interface between it and Ti₃C₂.The face-to-face coupling makes it form tighter large-area Schottky contact interface,which not only ensures the effective transfer of more charge from CdS to Ti₃C₂ nanosheets,but also suppresses photogenerated electron-hole pairs restructuring,allowing more photogenerated electrons can be added to the reduction reaction,while the increased specific surface area of the composite materiasl are conducive to the adsorption of reactant molecules and increase the rate of photocatalytic hydrogen production.