C₃N₄@SiO₂-Au Composite Nanofibers With Enhanced Visible Photocatalytic Activity

Water pollution has a strong impact on the sustainable development of human society.The solution for solving water pollution is extremely urgent.Semiconductor photocatalytic technology is one of the effective routes to resolve these problems.Graphite like carbon nitride（g-C₃N₄）has a similar two dimensional layered structure of graphite.It is a rising star as photocatalytic materials in the studies of photocatalysis.The nanosheets of g-C₃N₄ have good visible light catalytic activity,but the cyclic utilization is poor due to the difficulties of separation,and the aggregations during reaction process also reduce the catalytic efficiency.Thus,in this dissertation,g-C₃N₄ is uniformly immobilized on SiO₂ hollow nanofibers.And,the introduction of gold nanoparticles on SiO₂ hollow nanofibers further improves the quantum efficiency and the photocatalytic activity of the composite.The main results are as follows:（1）Electrospinning technique was used to prepare the hollow SiO₂ nanofibers.Furthermore,SiO₂-Au hollow nanofibers were obtained via in situ reduction method using SiO₂ nanofibers as templates.Finally,after calcination with urea as reaction source,the C₃N₄@SiO₂ and C₃N₄@SiO₂-Au composite hollow nanofibers were fabricated by using the SiO₂ or the SiO₂-Au hollow nanofibers as the carriers,respectively.The introduction of carriers can significantly improve the uniformity and dispersion of g-C₃N₄ nanostructures.（2）The C₃N₄@SiO₂ and C₃N₄@SiO₂-Au composite nanofibers show excellent photodegradation property of Rhodamine B under visible light irradiation,and the photocatalytic activity of C₃N₄@SiO₂-Au composite nanofibers is significantly higher than that of C₃N₄@SiO₂ composite nanofibers.The high dispersion of C₃N₄ on SiO₂ hollow nanofibers result high specific surface area for photocatalytic reaction,and the interaction between Au nanoparticles and g-C₃N₄ further improve the photocatalytic reactivity.（3）The C₃N₄@SiO₂ and C₃N₄@SiO₂-Au composite nanofibers have superlong one dimensional characteristics which is facial for precipitation in the practical reaction and separation.Thus,it is more convenient for application in operation and recovery.The three cycling catalytic reaction tests suggest that the obtained C₃N₄@SiO₂-Au composite nanofibers also have good stability,indicating their reusability.