Nano-sized Fe3O4 has been considered prominent in material science research due to its potential applications in multi-layered aspects. One of the simple and inexpensive methods of nanosized Fe3O4 synthesis is co-precipitation. However, this method has not provided a uniform size. Therefore, this study carried out a few modifications by using PEG-200 and PEG-1000 as a soft template with a volume ratio of 1:1, 1:3, and 1:5. The Fe precursors used in this study are iron sand from the Brantas River, Kediri-East Java, Indonesia. The XRD results showed that the use of PEG in the synthesis of Fe3O4 did not affect the Fe3O4 phase, and this study obtained a crystal size with a range of 6-12 nm. Based on morphological observations using SEM, the use of soft templates in Fe3O4 synthesis can reduce agglomeration rather than without using a PEG template. All Fe3O4 powder samples showed ferrimagnetic behavior with a saturation magnetization of 39.5-70 emu/g.
Technological advancement nowadays is detrimental to the environment. To deal with such a problem, waste decomposition should be carried out to produce a clean and healthy environment. In this study, the photodegradation method was used because it has advantages in efficiency and stability. The material used as a photodegradation catalyst was Fe3O4@ZnO nanoflowers. The synthesis of Fe3O4@ZnO nanoflowers was carried out using coprecipitation method for Fe3O4 and precipitation for composites. The variations in the mass of the catalyst used in this study were 50, 100, and 150 mg. The samples were characterized using an X-Ray Diffractometer (XRD) to analyze the phase, size, and crystal structure, Scanning Electron Microscopy (SEM) to determine morphology, and a photodegradation test to measure the photodegradation activity. The grain sizes of Fe3O4 and ZnO nanoflowers based on the Scherrer equation were 12.12 nm and 32.29 nm, respectively. Based on SEM characterization, the morphology of Fe3O4@ZnO nanoflowers showed a flower-like structure with an average diameter of 3.2 µm. The best performance of phenol photodegradation activity is 54.3 % obtained in the first cycle of 150 mg Fe3O4@ZnO nanoflowers under solar irradiation.
Light detectors are widely used in generating energy from sunlight, medicine, space communications, ozone layer monitoring and missile warning systems, and others. The active materials that potential used as a detector of visible light and UV is ZnO. However, ZnO has a high bandgap of 3.04 eV so it is not suitable for absorbing light at short wavelengths. Cuprous oxide (Cu2O) is a p-type of semiconductor with a small band, therefore it can increase the wavelength absorption range. The aim of this study is to improve the light response of ZnO nanorods by coating Cu2O. The samples were characterized by X-ray Diffractometer (XRD), Scanning Electron Microscopy (SEM), UV-Vis Spectrometry, FTIR, and photoresponse test. The results show coating Cu2O on ZnO nanorods succeeded in reducing the bandgap value, which is 2.47 eV. Reducing the band gap value is in accordance with the photoresponse test. The response of a sample that has a small bandgap is a fast response.
The poor stability of perovskite materials is a problem of concern in commercialization. In this study, we investigated the doping of magnesium cations (Mg2+) in PbI2 to improve the stability and efficiency of perovskite solar cells. The doping effect of Mg2+ can increase the crystallization rate. The perovskite film fabricated structure consists of ITO/TiO2/perovskite/CuO. The fabrication method used is a two-stage spin coating. The concentrations of MgAc2 were used 0, 0.75, 1, and 1.25 mg ml−1. The characterizations used are XRD (X-Ray Diffraction), UV-Vis, SEM-EDX. While the performance of solar cells is measured using a solar simulator. The XRD pattern shows that the sample has a crystal structure of MAPbI3, PbI2, and CuO phases. The MAPbI3 lattice parameter increased with increasing Mg acetate concentration. The grain size of the perovskite layer is between 5 - 15 μm, with a thickness of about 30 μm. The efficiency of perovskite solar cells increases with the increasing concentration of MgAc2.
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