Construction,modificiation And Photocatalytic Activity Of One-dimensional TiO₂/WO₃ Heterojunction

With the rapidly development of industry,energy crisis and environmental pollution due to the use of fossil has become a major challenge facing mankind.Phocatalytic technology can utilize solar energy to get clean hydrogen energy through the splitting of water,thus converting low-density solar energy into high-density chemical energy effectively,achieving conversion of green energy,and have important application prospects in addressing energy and environmental issues.Currently,the photocatalytic materials are mostly represented by wide band gap semiconductors such as TiO₂,although they can achieve photocatalytic water splitting for hydrogen production,but still exist the inherent problems and application bottlenecks can’t overcome:（a）wide band gap results in low solar utilization;（b）light quantum efficiency is low;（c）high overpotential for H₂ production;（d）photocatalyst is difficult to separate and recover.How to solve these four problems is the current research hotspot and international frontier issues in the field of photocatalyst hydrogen production.Very recently,the contraction of heterojunction photocatalytic system has become an ideal and effective solution because it not only can capture photo-induced holes reducing the electron-hole recombination,but also preserves excellent redox ability.Therefore,we combined TiO₂ nanomaterials with metal oxides to form heterojunctions,and modified with carbon and precious metals,thus promoting the separation of photogenerated carriers and the utilization of sunlight,characterized the morphology and phase of the prepared materials by SEM,TEM,XRD,UV-vis and XPS,and tested its photocurrents,impedance and photocatalytic hydrogen production.The main research contents are as follows:（1）Firstly,prepared TiO₂/WO₃ heterojunction nanofibers by electrospinning,then prepared TiO₂/WO₃@C heterojunction composite nanofibers by hydrothermal reaction,and discussed the effects of different tungsten contents on the photocatalytichydrogen production of pure TiO₂.Using the absorption of visible light of carbon layer to achieve the sensitization of TiO₂,the carbon layer as an electron collector and WO₃ as a hole collector,having a good inhibition of electron-hole recombination,improve the quantum yield of TiO₂,and promoting the improvement of photocatalytic hydrogen production.In addition,based on the protection of 3D nanoscale structure and the carbon layer,the photocatalyst can be effectively separated and recovered.（2）On the basis of the optimum titroduction of tungsten,added chloroplatinic acid in the precursor solution and prepared TiO₂/WO₃/Pt composite nanofibers by electrospinning,its photocatalytic hydrogen evolution compared with TiO₂/WO₃ nanofibers have been significantly improved.We have explored the mechanism through the photocurrent,impedance and so on,Schottky barrier will be formed when Pt and TiO₂ contacted,and Pt as an electron collector,WO₃ acts as a hole collector,promoting the separation of photogenerated charge.Besides,Pt has a lower overpotential than TiO₂,which can further promote the improvement of photocatalytic hydrogen production.（3）On the basis of the optimum titroduction of tungsten,added chlorauric acid in the precursor solution and prepared TiO₂/WO₃/Au composite nanofibers by electrospinning.The contraction of Au and TiO₂ will form Schottky barrier,the synergistic effect of Schottky and SPR effect will not only promote the separation of photogenerated charge,but also enhance the response to visible light,thus promoting the improvement of hydrogen production.Besides,the free-standing 3D network structure could improve photocatalyst’s separation and recovery effectively in the application of liquid phase.