Results obtained from FTIR and UVvis Essay

The morphologies of the synthesized magnetite PB nanocomposite and modified GODBSA/GA/Fe3O4PB/GC electrode were investigated by TEM and SEM. Figure 1 shows the TEM results of the typical synthesized magnetite PB particle. Numerous round shaped and cubic shaped associated compactly together were observed. Most of the particles are grouped randomly with big particle sizes which could attributed to the modification of the PB with Fe3O4. The obtained magnetite PB nanoparticles were with average particle size in the range 264108 nm. Compared to those reported on literatures, the obtained particles were a little larger maybe due to the modification of PB with Fe3O4. Also the shape and size of the particles depends on the experimental conditions such as reaction time, temperature, irons concentration and types, and pH value. The distribution on the PB support of magnetite nanoparticles with no uniform size seems to minimize the aggregation of the particles this attributed to the presence of PEG.
Figure 2 shows the SEM images for the modified Fe3O4PB/GC and GODBSA/GA/Fe3O4PB/GC electrodes. As seen in Figure (2a) the Fe3O4PB particles were joined compactly due to the electrostatic attraction between the particles and formed a composite particles. After the Fe3O4PB/GC modified electrode was coated with enzyme mixture, it is apparent that it covered completely the modified electrode surface indicating the successful immobilization of GODBSA/GA onto Fe3O4PB film (Figure2b).
To again verifying the formation of magnetite PB composite, microanalysis EDAX was taken. As seen in figure 1S supporting information elements content of the composite showing existing of (C, N, O and Fe) which are typical elements of Fe3O4 and PB.
Further verifying the formation of the magnetite PB nanoparticles, FTIR was used to characterize Fe3O4 and magnetite PB nanoparticles as shown in Figure (3). In Figure 3a of (Fe3O4), there is absorption band at 573 cm1 it is refer to the absorption peak of FeO bonds according to the literature in [18], also there is absorption peaks at around 3315 and 1600 cm1 which related to OH and HOH respectively. These peaks are attributing to the existence of interstitial water in the particles [6]. For the magnetite PB particles (Figure 3b), it displayed absorption band at 2085 cm1 which attributed to the CN group and another absorption band at 496 cm1 which related to the FeCNFe [5, 6, 19] indicating the formation of PB. Moreover, there is also absorption peak at 596cm1 referring to the FeO bond. Existence of peaks at 2085, 496, and 596 cm1 in this sample (Figure 3b) confirming the formation of magnetite PB nanoparticles through one pot hydrothermal synthesis.
UVvis spectroscopy was further used to investigate the formation of the magnetite PB composite as seen in (Figure 4). In Figure 4a of pure Fe3O4, no clear absorbance could be observed, however for the magnetite PB composite (Figure 4b) the mixed valence charge transfer band of the polymeric FeII CNFeIII at around 740 nm was observed. Both results obtained from FTIR and UVvis showed good agreement to the results which reported in the literature [20, 21].