Preparation Of Noble Metal-decorated G-C₃N₄/TiO₂ Heterojunction Nanofibers And Investigation Of Their Photocatalytic Properties For H₂ Production

With the gradual exhaustion of the non-sustainable fossil fuels,more and more attention has been focused on the development of clean and renewable energy source for fulfilling the rapid growing of economy and industrial production.Converting the solar energy into the environmentally-friendly fuels through a facile photocatalytic technique by using semiconductors has been emerged as a hot issue in the area of new-energy generation.This is because the “green” fuel,hydrogen,can be produced through photocatalytic water splitting or reduction.Graphitic carbon nitride?g-C₃N₄?is considered as an important visible-light-driven photocatalyst due to its narrow band gap,good chemical stability,nontoxic nature,easy synthesis,and low cost.In this thesis,the g-C₃N₄ is synthesized through a thermal polymerization method.Employing the as-synthesized g-C₃N₄,Ti?OC₄H₉?₄ and poly?vinyl pyrrolidone??PVP?as the precursors,the nanofibers of g-C₃N₄/Ti?OC₄H₉?₄/PVP composite were obtained through an electrospinning technique.After calcining the above composite nanofibers,the g-C₃N₄/TiO₂ heterostructure photocatalyst was fabricated.When introducing the noble metal salt into the electrospinning precursors,a series of noble metal?Au,Ag,Pt?/ g-C₃N₄/TiO₂ ternary heterostructure photocatalysts were constructed.These ternary heterostructure photocatalysts were characterized by XRD,SEM,?HR?TEM,FT-IR,XPS,and UV-vis/DR.The results indicate that the g-C₃N₄ nanosheets and noble metal nanoparticles are dispersed uniformly into the TiO₂ nanofibers.Photocatalytic H₂ production tests show that these ternary heterostructure photocatalysts exhibit a significantly high photocatalytic activity under simulated sunlight irradiation as compared to single-component photocatalyst?TiO₂ or g-C₃N₄?and bicomponent photocatalyst?g-C₃N₄/TiO₂?.This enhancement can be attributed to the promoted charge separation based on the semiconductor heterojunction effect and surface plasmon resonance?SPR?of noble metal nanoparticles.Among these ternary heterostructure photocatalysts,Ag/g-C₃N₄/TiO₂ photocatalyst show the optimal photocatalytic activity for H₂ production due to the overlapped absorption spectra between g-C₃N₄ nanosheets and Ag SPR.Besides,these ternary heterostructure photocatalysts possess good physical and chemical stability.Also,their unique macrostructure results in an excellent reusability in the photocatalytic liquid-phase reaction.