Control Of Localized Surface Plasmon Resonance Effect Of Defective Tungsten Oxide And Its Photocatalytic Performanc

With the development of industry,energy and environment have become one of the biggest problems facing humanity today.The emergence of photocatalysts provides a green,environmentally friendly,and sustainable method to solve this problem.However,the practical application of photocatalysis technology is still limited by the small light absorption range and low electron hole separation.In the past few decades,many methods have been studied to increase the light absorption range and electron hole separation of photocatalysts.The use of local surface plasmon resonance（LSPR）is an effective method to solve the above problems.In this article,a series of W₁₈O₄₉ based photocatalysts were prepared using a simple solvothermal method,and their LSPR effect was effectively regulated by constructing heterojunctions and doping,enhancing their ability to separate electrons and holes.In addition,its LSPR effect has also been utilized to explore full spectrum photocatalysis in the fields of energy and environment.The specific content is as follows:1.Preliminary exploration was conducted on the synthesis conditions of W₁₈O₄₉,and the synthesis method was optimized to prepare W₁₈O₄₉ with sea bile like morphology.The regular arrangement of W⁵⁺ions in the W₁₈O₄₉ crystal structure will introduce an intermediate state energy level in its band gap.The intermediate state energy level will increase the separation ability of electron holes and cause a strong LSPR effect with a large number of excited state electrons locally.On this basis,its photocatalytic degradation ability for pollutants is studied.2.A new preparation method has been developed to construct TiO₂/W₁₈O₄₉heterostructures.Research shows that the prepared TiO₂/W₁₈O₄₉ heterostructures have full spectrum absorption of ultraviolet visible infrared,good heterostructure interfaces,and many active sites.The excellent photocatalytic degradation performance of TiO₂/W₁₈O₄₉ heterostructure for formaldehyde was achieved by utilizing the LSPR effect of W₁₈O₄₉ in visible and infrared.99.3%of formaldehyde was adsorbed within60 minutes,while commercial activated carbon only adsorbed 31.0%of formaldehyde.94.1%of formaldehyde was degraded within 120 minutes under visible and infrared light,while TiO₂ only degraded 11.8%of formaldehyde.The mechanism was studied.Under visible light irradiation,electrons in the valence band of W₁₈O₄₉ were excited to the conduction band and intermediate state energy levels,and a large number of localized electrons in the intermediate state energy levels were excited again by infrared light to higher energy positions to form LSPR hot electrons;Due to the excellent heterojunction interface,LSPR hot electrons transfer to the conduction band of TiO₂ and react with adsorbed formaldehyde molecules,achieving effective degradation of formaldehyde under visible and infrared light irradiation.This work provides a new approach for the development of indoor formaldehyde degradation photocatalysts.3.Au/W₁₈O₄₉ plasma heterostructures were prepared by photoreduction and chemical reduction methods.The effective regulation of the W₁₈O₄₉ LSPR effect was achieved on the Au/W₁₈O₄₉ heterostructures using interface electron transfer effect and LSPR resonance coupling effect.The LSPR effect of W₁₈O₄₉ was directly utilized for photocatalytic hydrogen production and pollutant degradation.Research has found that there are two distinct electron transfer pathways in heterostructures prepared by two different methods.The excited state electrons and LSPR hot electrons of W₁₈O₄₉were transferred to Au nanoparticles on the heterostructure prepared by photoreduction method,which realized the long life of W₁₈O₄₉LSPR hot electrons and enhanced photocatalytic hydrogen production and pollutant degradation performance.The hydrogen generation rate reached 9 mol/g/h and 96.06%of dyes were degraded within 40 minutes.On the heterostructure prepared by chemical reduction method,the LSPR hot electrons of Au transfer to W₁₈O₄₉ and recombine with the holes in its valence band,which greatly reduces the electron hole separation ability of W₁₈O₄₉ and also brings the worst photocatalytic performance.This part of the work provides a new design approach for the development of direct LSPR photocatalysts.4.Mo doped W₁₈O₄₉ photocatalyst was prepared by a simple solvothermal method.The doping of Mo regulates the band structure of W₁₈O₄₉,which makes the intermediate state energy level and conduction band position rise,leading to the enhanced reduction ability of excited state electrons,and increases the concentration of local electrons in the intermediate state energy level,resulting in a stronger LSPR effect.At the same time,its photocatalytic reduction performance for CO₂ was studied.The results showed that the doping of Mo optimized the surface state of W₁₈O₄₉,increased CO₂ adsorption,and the heterogeneity of surface Mo⁵⁺-W⁵⁺atomic pairs brought strong CO₂ activation ability.The Mo-O bond had stronger covalence than the W-O bond,making it easier for photo generated electrons to transfer to the surface.Through the above band structure regulation and surface state optimization,a more excellent CO₂ photoreduction reaction with excellent reusability and product selectivity was achieved in gas-solid reactions.Its CO yield is 57.06μmol/g/h is the best reported CO₂ photo reducing agent on W-based oxides to date.This work provides a coupling scheme to enhance charge motion behavior,demonstrating the potential of coupling enhancement strategies in the preparation of high-efficiency photocatalysts.