Construction And Performance Of A Novel TiO₂-based Photocatalyst For Hydrogen Production By Photolysis Of Water

The massive burning of fossil energy during the rapid development of modern industry has caused a series of environmental problems such as the greenhouse effect and the melting of glaciers,and it has also caused the depletion of global primary energy.Therefore,it is imminent to develop green and renewable energy.Due to its high combustion calorific value,hydrogen has only water and no carbon emissions,so it is very likely to replace fossil energy as the main fuel energy in the future.Therefore,how to efficiently produce hydrogen has attracted much attention.At present,the main methods of hydrogen production include:hydrogen production from fossil fuels,hydrogen production from industrial by-products,hydrogen production from biomass,and hydrogen production from electrolyzed water.However,these traditional hydrogen production technologies are energy-intensive,complicated to operate,and produce CO₂and other greenhouse gases during the hydrogen production process,so they cannot be called truly carbon-free green energy.Photocatalytic water splitting hydrogen production technology uses semiconductors as catalysts to split water into hydrogen under the drive of sunlight.Photocatalytic hydrogen production means that as long as there is sunlight and water,hydrogen can be continuously produced,thus effectively solving the crisis caused by the greenhouse effect and the depletion of fossil energy.The advantages of hydrogen production by photolysis of water are green,energy-saving,pollution-free,and renewable,and it has become one of the key directions in the field of catalysis in the future.Efficient and stable semiconductor photocatalysts are the core of photocatalytic water splitting to produce hydrogen,and it is also the prerequisite for the application of this technology to actual production.Titanium dioxide（TiO₂）is one of the most researched and applied photocatalysts due to its advantages of high efficiency,non-toxicity,easy preparation,and good stability.However,TiO₂ mainly has the following disadvantages and deficiencies:（1）low light utilization rate;（2）large migration energy barrier for photogenerated carriers and easy recombination;（3）large migration distance for photogenerated electrons and few reactive sites.Modification of catalyst is an effective means to improve photocatalytic activity and photocatalytic efficiency.Therefore,aiming at the three major defects of TiO₂ at present,this study focuses on the research work of"the construction and performance of a new type of TiO₂-based photocatalyst for hydrogen production from photolysis of water".The main research contents are as follows:（1）Preparation of C-N co-modified TiO₂ photocatalyst and its performance of photo-splitting water for hydrogen production.Chicken feathers were chosen to provide templates for the modification of TiO₂,and a TiO₂ photocatalyst(T₃F_N1)with a three-dimensional rod-like structure rich in wrinkles on the surface was successfully prepared by solvothermal method,and characterized by SEM,XRD,XPS,ESR,BET,UV-vis DRS,etc.And photocatalytic water splitting hydrogen production experiments found that chicken feather templates provide natural C and N sources for the modification of TiO₂ at the same time,N is doped into the TiO₂ lattice in the form of occupying O_V in the TiO₂ lattice,and C is amorphous the form exists on the surface of TiO₂;under ultraviolet-visible light,the hydrogen production rate of T₃F_N1 is 405.18μmol·g^-1·h^-1;the utilization rate of light source and the separation efficiency of photogenerated electron-hole pairs of modified T₃F_N1 are significantly improved.（2）Preparation of Pt single-atom-anchored TiO₂ quantum dots and their photolysis of water to produce hydrogen.In order to further improve the performance of photocatalytic hydrogen production,Pt was selected as a cocatalyst to modify TiO₂.Pioneering and successful preparation of Pt single-atom-anchored ultra-dispersed TiO₂quantum dots with a particle size of about 9 nm by a solvothermal method.Photocatalytic hydrogen production experiments show that under ultraviolet-visible light,the hydrogen production rate of 0.2%Pt-TiO₂ is 77.6 mmol·g^-1·h^-1;The atomic form is effectively anchored between the two O atoms of TiO₂;combined with the photoelectric analysis test and DFT calculation results of the material,it is confirmed that Pt single-atom anchoring greatly reduces the migration energy barrier of excited electrons from the bulk phase to the surface,making photogenerated electrons Migrate rapidly to the surface while avoiding recombination with holes in the bulk.At the same time,Pt atoms can receive excited electrons and promote their accumulation on the catalyst surface near the Pt site,and then participate in the photocatalytic water splitting hydrogen production reaction.（3）The preparation of Pt-2D TiO₂ photocatalyst and its performance of photolysis of water for hydrogen production.Aiming at the problems of long migration distance of photogenerated electrons and few reactive sites in current TiO₂-based photocatalyst materials,P123 was selected as the surfactant,and an ultra-thin two-dimensional layered graphene-like structure 2D TiO₂ was successfully prepared by solvothermal method.After chemical impregnation and Ar/H₂ reduction,Pt nanoparticles were modified on the surface of TiO₂ and the optimal preparation conditions of the catalyst were determined:solvothermal temperature of 150°C,solvothermal time of 20 h,calcination temperature of 500°C,Pt The loading is 0.1 wt%.The research results of spectroscopy,photoelectrochemical characterization and photocatalytic hydrogen production performance show that Pt is deposited on the surface of TiO₂ in the form of nanoparticles,and P123 as a surfactant can increase the specific surface area of TiO₂,shorten the migration distance of photogenerated electrons,and improve the photogenerated load.The lifetime of the flow electrons makes more photogenerated electrons become effective electrons and migrate to the surface of the catalyst to participate in the photocatalytic water splitting hydrogen production reaction;the photocatalytic hydrogen production rate of 0.1%Pt-2D TiO₂ under ultraviolet-visible light reaches 106.53 mmol·g^-1·h^-1,compared with the TiO₂ catalyst without adding P123,the photocatalytic hydrogen production performance increased by 50%.（4）Construction of an array flat solar photolysis water splitting hydrogen production device.In order to explore the practical application value of the TiO₂-based photocatalyst developed and prepared above,this research independently designed and built a photocatalytic water splitting hydrogen production reaction device with a light-receiving top and a replaceable catalyst.The research results show that:the photocatalyst is scraped onto the glass plate and the disassembly design of the reaction device realizes the free replacement of the catalyst of the device;the activity of 0.1%Pt-2D TiO₂ in the device is the most stable,and the performance of photolysis of water to produce hydrogen is the best.After 45 hours of continuous experiments,the hydrogen production capacity of the device continued to reach 123.37 mmol·g^-1·h^-1.