Preparation Of PAN@PANI@ZnO Flexible Composite Nanofibers And Their Photocatalytic Properties

Semiconductor photocatalysis as a green technology for water pollution has important applications in energy conservation and environmental protection.ZnO has been regarded as a great photocatalytic material due to its direct bandgap property?3.37eV?,excellent light absorption for UV,suitable energy band structure.However,ZnO nanopowder materials still face the following problems as photocatalysts:First,it is easy to agglomerate in the liquid phase photocatalytic reaction to reduce the specific surface area,and the reactants are suspended in the solution,which is not conducive to recovery;Second,photoelectrons and holes are easily recombine to result in decreasing photocatalytic performance.Based on the above problems,this paper prepared the flexible ZnO-based composite nanofibers by the method of electrospinning,in-situ polymerization and atomic layer deposition technology?ALD?to improve the photocatalytic and performance properties of materials,the main study is as follows:?1?Polyacrylonitrile?PAN?nanofibers were prepared using electrospinning technology,using this as a template,PAN@ZnO flexible composite nanofibers were prepared by ALD technology,the immobilization of ZnO nanomaterials on PAN nanofibers was achieved.The results of morphology and structure test show that ZnO was uniformly deposited on the surface of PAN nanofibers to form a core-shell structure.The photocatalytic results show that the photocatalytic activity of PAN@ZnO composite nanofibers increases with the increase of ALD cycles.PAN@ZnO composite nanofibers not only can prevent the agglomeration of ZnO nanopowders,but also can be recycled by self-settling because of its macroscopic mat structure.After three cycles of experiments,the photocatalyst still maintains good photocatalysis.?2?Using the electrospun PAN nanofibers as carrier,the PAN@PANI composite nanofibers were prepared by in-situ polymerization method;using this as a template,PAN@PANI@ZnO heterojunction composite nanofibers were prepared by ALD technique,the immobilization of ZnO/PANI heterojunction on electrospun polyacrylonitrile nanofibers was achieved.The relative content of ZnO/PANI heterojunction can be changed by adjusting aggregation time and ALD cycles.Because of the presence of ZnO/PANI heterojunctions,the separation of electrons and holes can be effectively promoted,thus,compared to PAN@ZnO and PAN@PANI nanofibers,the PAN@PANI@ZnO composite nanofibers shows higher photocatalytic activity by a factor of 2.1.The result of photocurrent test shows that the PAN@PANI@ZnO composite nanofiber exhibited the highest photocurrent density,further demonstrating that the heterojunction can more effectively separate charges.The capture experiments show that during the photocatalytic reaction,h⁺,e^-,·OH and·O₂^-can participate in the photocatalytic reaction,and e^-plays the most important role.Because PAN@PANI@ZnO composite nanofibers have a macroscopic mat structure and flexibility,they can be easily recovered by self-settling.After five cycles of experiments,PAN@PANI@ZnO composite nanofibers exhibit stable photocatalytic performance.