Preparation And Properties Of Bio-templated Photocatalytic Materials

Today,the traditional energy system based on fossil fuels faces two major problems of energy crisis and environmental pollution.One of the effective strategies to solve the above problems is to use renewable energy to convert the most common and abundant water resources on earth into hydrogen,and store and use it.As a clean,non-polluting carrier with high energy density,hydrogen has received more and more attention.The bright future of the hydrogen economy also implies that more efficient and environmentally friendly green hydrogen production technologies need to be developed urgently.Among them,photocatalytic/photoelectric catalytic hydrogen production is one of the most common solutions to convert solar energy into hydrogen energy.However,there are still a series of bottlenecks in practical application of TiO₂-based photocatalysts commonly used in photo/electrocatalytic hydrogen production reactions,such as narrow photoresponse range（ultraviolet region）,low solar-hydrogen energy conversion efficiency,poor photocatalytic stability,etc.In order to better solve this scientific problem.In this paper,a series of efficient photo/electrocatalysts with composite components such as Ti,C,N,P and rare earth ions were prepared by selecting natural biomass materials with good light-responsive properties as templates,and the geometry of the biological templates was deeply explored.The structure-activity relationship between the type and composite components and their photoelectric catalytic properties provides a certain scientific basis for the design and development of new high-efficiency photo/electrocatalytic materials.Specifically,this dissertation prepared a series of pollen-carbon photocatalysts using lotus pollen as the carbon source.Benefiting from the natural surface folds and rich hierarchical pore structure of lotus pollen,it is conducive to the efficient separation of photogenerated carriers generated after exposure to light,and greatly improves its light utilization efficiency.After that,the prepared pollen carbon materials were continuously modified by different methods,and the photo/electrocatalytic water/organic small molecule solution hydrogen production performance of the modified composite pollen carbon materials was deeply explored.The main research results are as follows:（1）Using lotus pollen as the precursor,the pollen carbon material（LP-C）was successfully prepared by a two-step calcination method,and a series of characterizations such as XRD,FE-SEM,EDS mapping,and XPS were carried out.It was found that the pollen carbon material mainly It exhibits a typical amorphous carbon structure with an average particle size of about 40μm,a unique surface wrinkle morphology,rich pore structure and self-doping of N,P and other elements.The photocatalytic hydrogen production performance of the pollen carbon material and commercial carbon black was tested under the full spectrum,and it was found that the pollen carbon material showed better hydrogen production performance than carbon black in the test.Among them,the hydrogen production performance of LP-C-600(35μmol·g^-1)is best.（2）The pollen carbon material（Er/LP-C）modified with rare earth Er element was successfully prepared by impregnation method.The Er element was uniformly distributed on the surface of the pollen carbon material by high-power transmission electron microscopy（HRTEM）and EDS mapping characterization.It not only provides more active sites for the photo/electrocatalytic water splitting reaction,but also further improves the separation efficiency of photogenerated electrons and holes.The peak photocurrent density（3.1μA/cm²）of the modified sample 20%Er/LP-C-600 in the presence of a bias voltage of1.0 V vs.Ag/Ag Cl and subjected to AM 1.5G simulated sunlight irradiation),which is 1.28times of the photocurrent density（2.5μA/cm²）of the pollen carbon material LP-C-600under the same test conditions.（3）Based on the limitation of light absorption range of single-component TiO₂material,the composite material of TiO₂ and pollen carbon（TiO₂/LP-C）was prepared from the perspective of component optimization.Through characterization,it is found that the prepared TiO₂/LP-C composite well preserved the surface wrinkles and hierarchical pore configuration of the pollen carbon itself are well preserved.The performance test of the composite material shows that the photo-splitting water/organic small molecule hydrogen production performance,electrical conductivity and band gap structure of the composite are better than those of pure TiO₂ and pollen carbon,indicating that biomass carbon modification of TiO₂ can effectively optimize its performance.energy level structure to improve its photo/electrocatalytic activity for water/organic small molecule splitting.Naturally,the research work in this paper makes full use of the unique biological structure of lotus pollen and its rich trace elements,and successfully developed a series of efficient photo/electrocatalytic materials,which proves that biological templates are used in the development of efficient photo/electrocatalytic materials.The unique role in the bio-templated carbon materials broadens the application field of bio-templated carbon materials,and also provides new ideas for the design of efficient photo/electrocatalytic hydrogen production catalysts.