Microstructure analysis of Fe3O4/Polypyrrole composite synthesized by Sol-Gel method

The composite is a material that is very important in inserting nanoparticles that act as fillers in a matrix. The filler used in this study is Fe3O4 and the matrix used as a polymer is Polypyrrole (PPy). This research aims to analyze the microstructure of Fe3O4 /PPy composite synthesized by sol-gel method. This research was conducted by varying the composition of Fe3O4:PPy including 30%, 40%, 50%, 60%, and 70% w/w. The sample was characterized by Fourier Transform Infrared (FTIR) and Scanning Electron Microscope (SEM). The results of the FTIR characterization, it was found that the Fe3O4 /Polypyrrole has functional groups O-H, C≡C and C=C. The results of SEM characterization, the particle sizes of each variation composition of Fe3O4:PPy 30%, 40%, 50%, and 70% w/w are 3µm, 3.1µm, 4µm, and 4.5µm, respectively. Based on the results of the study, the greater the composition of the polypyrrole, the greater the particle size.


Introduction
Fe3O4 at nano size contains iron sand which has advantages compared to other compounds, where iron sand in response to external magnetic fields is superior.Thus,  3  4 at the nanoscale containing iron sand has a great opportunity to be applied in various industrial and electronic fields.A thin layer of magnetic nanoparticles contained in a polymer matrix can be applied to mechanical, optical, electronic, and magnetic technologies [1].Recently, supercapacitors have shown great potential to meet energy needs, especially portable electrical energy.This supercapacitor has shown outstanding performance as an environmentally friendly energy storage system due to its faster charging process, high power density, long-term stability, low cost, and relatively easy production process.One of the most widely used polymer types in research is Polypyrrole (PPy).Polypyrrole (Ppy) is used in various potential applications such as gas sensors, biosensors, cables, capacitors, anti-electric coatings, polymer batteries, anti-electrostatic coatings, and microactuators, biomedical, electronic devices, and others [2].
In the manufacture of composites, several methods are used, one of which is the spin coating method and the sol gel method.In this study, the sol gel method was used for the manufacture of composites Fe3O4/PPy.The sol gel method is a method for making nano-sized particles, the sol gel method in the process uses a wet technique because the process it goes through involves a solution as the medium [3].The main motivation for this research is to utilize Fe3O4 from iron sands of West Sumatra which has been synthesized recently [4] so that it is cheaper.Fe3O4 has been extensively studied in many research fields due to its abundance, low cost and environmental friendliness.The theoretical electrochemical capacity of Fe3O4 as an electrode for a Lithium-ion battery is 928 mAhg -1 .With an electronic conductivity of up to 2x10 4 Sm -1 , Fe3O4 can be a promising anode material for Lithium-ion batteries [5].
On the other hand, Polypyrrole (PPy) has high conductivity and shows dramatic changes in its electronic structure and physical properties in the protonated state.In addition to the unique properties of PPy, PPy is very stable in air and has high electrical conductivity, low cost, easy preparation and environmental stability [6].

Method
The type of research used is experimental research, The research was carried out in several stages, namely, preparation of Fe3O4 precursors, preparation of  3  4 /polypyrrole composites, microstructure characterization of Fe3O4 and data analysis.Fe3O4/polypyrrole composite was prepared with composition of Fe3O4:PPy; 30%, 40%, 50%, 60%, and 70% (w/w).The tools used in this research are HEM-E3D, magnetic stirrer, digital scale, measuring cup, evaporating dish, and thermometer.The materials used are distilled water, aquabidest, tapioca flour, n-hexane, ethanol, oleic acid, ethylene glycol, NaOH, and polypyrrole.The characterization tools used are Fourier Transform InfraRed (FTIR), and Scanning Electron Microscope (SEM).

Results and Discussion
The Fe3O4/polypyrrole composite study were tested using several characterization tools.To see the functional groups of Fe3O4/polypyrrole composite, a Fourier Transform Infrared (FTIR) characterization tool was used, and to see the morphological results in the form of grain size of  3  4 /polypyrrole particles, a Scanning Electron Microscope (SEM) characterization tool was used.
The results of the FTIR characterization can be used to determine the functional groups of the Fe3O4/Polypyrrole nanocomposites.The functional groups are obtained from reading the graphs of the FTIR characterization results which consist of wave numbers and wave transmission.FTIR characterization results for the Fe3O4/Polypyrrole composite with composition variations of 30%, 40%, 50%, 60%, and 70% can be seen in Figure 1. Figure 1 shows the relationship between the absorption frequency of  3  4 /polypyrrole composites to the number of wave numbers at a certain distance.In the resulting graph functional groups with almost the same wavenumber.From the composition variation data, respectively, 30%, 40%, 50%, 60%, and 70%, the wave numbers reached 2403.09cm -1 , 2334.31cm -1 , 2323.06 cm -1 , 2335.29 cm -1 , and 2313.92cm -1 , the wave number shows the state of the O-H group.The absorption bands at wave numbers 2102.85cm - , 2098.35cm -1 , 2103.94cm -1 , 2102.09cm -1 , and 2097.96cm -1 , are the state of the C≡C group.The absorption bands at wave numbers 1719.21cm-1 , 1713.13cm -1 , 1717.76 cm -1 , 1712.21cm -1 , and 1700.70 cm -1 represent the state of the Polypyrrole group that has been successfully combined with  3  4 , the other peak at 1627.9 cm -1 showed a decrease in the sharpness of the absorption peak, which indicated that PPy had been successfully composed with  3  4 nanoparticles.The absorption bands at wave numbers 831.26cm -1 , 831.10cm -1 , 829.18cm -1 , 829.19cm -1 , and 829.95cm -1 represent the state of the C=C group.Functional Group C=C is a functional group owned by Polypyrrole, in another research [7], which stated that there was a similarity in the absorption of polypyrrole functional groups in PPy/bacterial cellulose composites indicating that the synthesis of PPy/bacterial cellulose was successful.This can be seen by the stretching vibration for the C=C bond which is a characteristic of polypyrrole.

and 70%
Furthermore, for the characterization of  3  4 /polypyrrole composite using SEM showing the morphological results in the form of particle size, the results of characterization using SEM are shown in Figure 2. 30%, (b).40%, (c).50%, and (d).70% In Figure 2, it can be seen that for each composition variation there are uneven clusters.The results of the analysis using SEM showed varying particle size patterns for all compositions.In morphology, the size of the particles does not look uniform and there is quite a lot of agglomeration for each composition variation.Irregularity of the particle size can be caused by the accumulation of several substances.
Based on the data for particle size, it was obtained that the particle size data varied for each composition.For the largest particle size obtained at 70% variation, and the smallest particle at 30% composition, as shown in table 1.In table 1 for particle size, various particle size data are obtained for each composition.The largest particle size was obtained at 70% variation, and the smallest particle at 30% composition.The formed particles tend to form bonds with other particles which are often called agglomeration.This is because iron sand has magnetic and electrical properties which in each particle will tend to attract each other and form lumps like particles.

Conclusion
From the results of research, it can be concluded that  3  4 /Polypyrrole composites have been successfully prepared by sol gel method with variations in the composition of Fe3O4 in Polypyrrole.The composition of Fe3O4 is influence the microstructure and particle sizes of the composite.The next stage of this research is to test the use of the Fe3O4/PPy composite as a battery anode.

Table 1 .
Particle size data for each composition variation of Fe3O4