Fabrication Of CdS/Polyacrylonitrile Hybrid Nanofibers And Their Application

Electrospinning has been recognized as the most simple and efficient technique for the fabrication of continuous polymer nanofibers, organic-inorganic hybrid nanofibers and inorganic nanofibers so far. The superiorities of nanofibers in size, specific surface area and mechanical property make them widely used in areas of gas sensing, catalysts, tissue engineering scaffolds, reinforcing materials and photoelectric materials, etc. This thesis prepared binary CdS-OH/polyacrylonitrile (PAN) hybrid nanofibers and ternary CdS-OH/MWCNT/PAN hybrid nanofibers via one-step co-electrospinning method. This research work includes the following two aspects:(1) CdS-OH/PAN hybrid nanofibers with average diameter of320nm were syntehsized via one-step co-electrospinning. CdS-OH nanoparticles (size:5nm) suspension was firstly prepared in N,N-dimethylformamide (DMF) by the reaction of CdCl2, Na2S and2-mercaptoethanol, then the suspension was mixed with PAN/DMF solutions to make spinning solutions, followed by electrospinning to make CdS-OH/PAN hybrid nanofibers. Experimental results showed that, CdS-OH nanoparticles had the same crystallographic structure as cubic zinc blende CdS, and nanoparticles were evenly distributed in the PAN nanofiber. Thermogravimetrical analysis demonstrated that hybrid nanofibers were more thermally stable than neat PAN nanofibers. Due to the large specific surface area of hybrid nanofibers, they displayed excellent photoluminescent property. The fluorescence lifetime of hybrid nanofibers was4.2ns. Additionally, CdS-OH/PAN hybrid nanofibers possessed excellent photocatalytic hydrogen production efficiency with a rate of13.5μmol/h·g fiber containing60mg of CdS-OH nanoparticles. CdS-OH/PAN hybrid nanofibers were further heat treated at265℃to transfor into CdS/PAN hybrid nanofibers, but CdS/PAN hybrid nanofibers didn’t show better fluorescence and photocatalytic hydrogen production performance than CdS-OH/PAN hybrid nanofibers. The CdS-OH/PAN hybrid nanofibers with high specific surface area could be good fluorescence and photocatalytic hydrogen production material.(2) CdS-OH/MWCNT/PAN (CMP) hybrid nanofibers with high photocatalytic degradation performance were synthesized via one-step co-electrospinning. The suspension of CdS-OH nanoparticles (size:5nm) in N,N-dimethylformamide (DMF) was first mixed with MWCNTs by sonication then further mixed with PAN/DMF solutions to make spinning solutions, followed by electrospinning to make CMP hybrid nanofibers. Experimental results showed that, the CdS-OH nanoparticles and MWCNTs were evenly distributed in PAN nanofibers of ca.300nm in diameter. CdS-OH nanoparticles tended to distribute along with the MWCNTs, while the long axis of most MWCNTs paralleled to the axis of nanofiber, so the CdS-OH nanoparticles distribute along the axis of nanofiber regularly with the introduction of MWCNTs. Thermo gravimetrical analysis demonstrated that CMP hybrid nanofibers were more thermally stable than neat PAN nanofibers. The CMP hybrid nanofibers, especially0.5CMP hybrid nanofibers, displayed excellent photocatalytic degradation performance to organic dyes, the photodegradation ratio of0.5CMP to Methyl Orange (MO) and Rhodamine B (RhB) could reach up to93.7%and97.5%, respectively.