Deposition of ZnO Thin Films by Spray Coating Technique for Photocatalytic and Photochemical Degradation of Methylene Blue (MB)

Deposition of a thin layer of Zinc Oxide (ZnO) on glass substrates by spray coating techniques has been done. ZnO is a semiconductor with band gap energy of ~ 3.2 eV and has the properties as oxidation photo catalysts that will transform harmful compounds and toxic substances in water into harmless compounds. ZnO thin film deposition is conducted by making gel ZnO with dissolving zinc acetate dehydrate (Zn(COOCH3)2.2H2O into a solution of isopropanol ((CH3)2CHOH) and monoethanolamine (MEA: HOCH2CH2NH2) at room temperature with a concentration of 0.3 M zinc acetate and the molar ratio is 1:1. ZnO gel is placed on the spray hole and sprayed on a glass substrate which has been heated at a temperature of 250°C at a pressure of 70 psi to form a thin layer. A thin layer is sintered at a temperature of 450°C for 2 hours. A ZnO thin layer then used as a photocatalytic and photochemical degradatioan of methylene blue (MB) with and without stirring. The microstructure analysis by using XRD show that the thin layers having polycrystalline wurtzite structure with orientations (100), (002), (101) and (110). EDS characterization showed that thin layers of ZnO consists of 50.27% and 49.73% zinc and oxygen atomic, respectively. ZnO photocatalyst reaction by using ultra violet light (UV) for 3 hours has been reduces the concentration of MB until 97.05%. A high percentage of color degradation MB performed by treatment with stirring

ANALISIS STRATEGI KEPALA SEKOLAH DALAM PENILAIAN KINERJA GURU PADA KURIKULUM MERDEKA DI SDN CIKARET

This study aims to analyze the principal\u27s strategy in assessing teacher performance in the implementation of the Merdeka Curriculum at SDN Cikaret. The Merdeka Curriculum is the focus of the study because it is a new innovation in the world of education in Indonesia that emphasizes relevant, inclusive, and student-oriented learning. This study uses a qualitative research method. case study approach by collecting data through in-depth interviews, observations, and analysis of related documents. The principal at SDN Cikaret has succeeded in developing a teacher performance assessment strategy that is in accordance with the principles of the Merdeka Curriculum. The development of comprehensive and relevant assessment instruments and the implementation of training programs for teachers are integral parts of this strategy. So that the implementation of this performance assessment was successfully carried out on time and the assessment results were good. Overall, this study shows the importance of the role of the principal in developing effective strategies in assessing teacher performance in the context of the Merdeka Curriculum can make a significant contribution to improving the quality of education at SDN Cikaret and supporting the realization of national education goals

The Electrical Properties of Al, ga1-Xn Thin Films Deposited on Si(111) Substrate by Chemical Solution Deposition Method

AlxGa1-xN thin films with the GaN buffer layer was deposited on Si(111) substrate by chemical solution deposition (CSD) method. The objective of this research was to evaluate the electrical properties of AlxGa1-xN with variation of Al mole fraction. The source for Ga and Al were gallium oxide (Ga2O3) and aluminum oxide (Al2O3), respectively as group III precursors and radical nitrogen resulted by high temperature decomposition of nitrogen gas. The mole fractions of solutions were varied between 15 to 35%. The formed white crystal was dissolved in ethylene diamine to form gel with molarities of 3-6 M. Therefore, the gel was superimposed on substrates Si with spin-coater at speed of 1100 rpm. The formed layer was then sintered at temperature of 900 C o such that it decomposed at N2 gas environment to form AlxGa1-xN. The composition of films was measured by energy dispersive of x-ray (EDX) and the measured Al concentrations were in the range of 9.52% to 24.19%. The electrical transport of the films was measured by means of Hall effect measurement at room temperature. The Hall mobility decreases with the increase of aluminum (Al) concentration and decrease carbon concentration. The resistivity increases with the increase of Al concentration. From the Hall effects measurement the AlxGa1-xN films have n-type conduction originated from nitrogen vacancy

Deposition of ZnO:Ag Photocatalyst Using Spray Coating Technique and Its Application for Methylene Blue and Methylene Orange Photodegradation

ZnO:Ag thin films have been successfully deposited on glass substrates by spray coating technique with various Ag content of 2%, 3%, 4% and 5%. The ZnO:Ag thin films used to photodegrade the dye methyl orange and methylene blue using ultraviolet (UV) irradiation. ZnO:Ag solution was synthesized by dissolving zinc acetate dehydrate (ZnAc) in isopropanol then monoethanolamine (MEA) and Silver nitrate added into that solution at room temperature. The concentration of zinc acetate was 0.3 M and the molar ratio of MEA : ZnAc was 1:1. The solution was stirred by a magnetic stirrer at a temperature of 70°C for 30 minutes to obtain a clear and homogeneous solution. ZnO:Ag gel was sprayed on a glass substrate and then heated at temperature of 400oC for 15 minutes. Optical properties of ZnO:Ag thin films were characterized by using UV-Vis spectroscopy. The research showed that the incorporation Ag into ZnO can enhance photocatalytic activity due to the Ag depressed the recombination rate. In addition, the higher ion Ag concentration was decreased bandgap energy. The photocatalityc activity of ZnO:Ag could degraded methyl orange dye up to 42.68% for ZnO: Ag 4%, 45.45% for ZnO: Ag 5% and the degradation of methylene blue dye is reached up to 99.21% for ZnO:Ag 4% and the ZnO: Ag 5% thin films could degraded up to 100% under UV irradiation for 10 hours

KAJIAN SIFAT OPTIK LAPISAN TIPIS FOTOKATALIS NANO KOMPOSIT ZNO/TIO2 YANG DIDEPOSISI DI ATAS KACA DENGAN METODE SOL-GEL

Telah berhasil dideposisi lapisan tipis nano komposit ZnO:TiO2 di atas substrat kaca dengan metode sol-gel. Lapisan Tipis nano komposit ZnO:TiO2 dibuat dengan memvariasi volume larutan TiO2 dari 0-100% terhadap larutan ZnO Deposisi lapisan tipis dilakukan dengan cara disemprotkan di atas kaca pada temperatur 250oC selama 15 menit. Hasil deposisi diuji sifat optiknya dengan UV Vis spektrofotometer. Peningkatan konsentrasi TiO2 menyebabkan lapisan tipis yang terbentuk menjadi lebih transparan atau menurunkan nilai absorbansinya lapisan nano komposit hasil deposisi. Semakin besar konsentrasi TiO2 menyebabkan penurunan nilai celah pita energinya. Diperoleh besarnya nilai celah pita energi lapisan tipis ZnO:TiO2 antara 2,82 eV - 3,02 eV. Nano komposit ZnO:TiO2 dengan perbandingan 50%:50% menghasilkan sifat optik yang kurang baik. Hasil pengujian foto aktivitas foto katalis nano komposit menunjukkan bahwa limbah limbah pewarna methylene blue lebih efektif didominasi oleh mayoritas ZnO sedangkan penambahan TiO2 menyebabkan lapisan mempunyai kemampuan foto degradasi rendah

Effect of Annealing Treatment on the Optical Properties of Zinc Oxide (ZnO) thin film prepared by MOCVD

The annealing treatment of ZnO thin film at various temperatures was performed. The effect of this treatment on the optical properties of ZnO thin film were investigated in order to apply this film to optoelectronic devices. The optical transmittance spectra  were measured and it was found that the transmittance in UV-VIS region decreased with annealing temperature . The loss of light is mainly due to  the increase of carrier density, resulting from increased oxygen vacancies during the annealing process at 300°C. It was also found that the absorption edge shifted to lower energy when the film was annealed at 300°C in air

French Fries-Like Bismuth Oxide: Physicochemical Properties, Electrical Conductivity and Photocatalytic Activity

Bismuth oxide synthesis using hydrothermal method has been conducted. This study aims to examine the effect of the hydrothermal reaction time on product characteristics and photocatalytic activity in degrading methyl orange dye. Bismuth oxide synthesis was initiated by dissolving bismuth nitrate pentahydrate (Bi(NO3)3.5H2O) and Na2SO4 in a distilled water and added NaOH gradually. The solution formed was transferred into a Teflon-lined autoclave and heated at 120 °C with time variations of 8–16 h. The formation of bismuth oxide was indicated by the vibrations of the Bi−O−Bi and Bi−O groups and the crystal structure consisting of a-Bi2O3, β-Bi2O3, and g-Bi2O3. In addition, the highest photocatalytic activity can be examined through several factors, such as: content of Bi−O−Bi and Bi−OH groups, crystal structure, band gap values, morphology, and surface area, acquired as a result of the effect of hydrothermal reaction time. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Identification Of Java Agate Elements Using Libs Methods

Agate is a stone that is created due to natural processes from the deposition of fossils and the formation of minerals that combine to become an agate. In essence, agate contains elements contained therein. The content of these elements can be used to distinguish the type of agate. Several methods are used to detect the elemental content of agate, including X-Ray Fluorescence and X-Ray Diffraction methods. In this study, agate will be tested using the LIBS method. The LIBS method is an alternative and effective method for identifying elements from a sample because this method does not require the sample to receive special treatment. Laser plasma optimization is done by varying the laser energy. The higher the value of the laser energy given, the intensity of the elemental spectrum will be higher. The results of the LIBS method show compatibility with the XRF method as a comparative study. The results showed that the elements contained in the agate are the elements Al, Mn, Si, Fe, Mg, Na, and Ca

MIKROSTRUKTUR SENG OKSIDA YANG DISINTESIS MENGGUNAKAN EKSTRAK DAUN ANTING-ANTING

Cakupan aplikasi yang luas dari seng oksida telah meningkatkan produksi seng oksida menggunakan berbagai metode fisika dan metode kimia. Penggunaan bahan kimia berbahaya dalam produksi seng oksida, mendorong pemanfaatan bahan alam yang ramah lingkungan untuk mereduksi dampak lingkungan.  Penelitian ini bertujuan untuk mensintesis seng oksida dengan memanfaatkan ekstrak daun anting-anting.  Seng oksida disintesis menggunakan proses presipitasi dari campuran larutan seng nitrat dengan ekstrak daun anting-anting.  Produk presipitasi dikalsinasi pada temperatur 500oC selama 3 jam.  Mikrostruktur produk presipitasi dianalisis menggunakan difraksi sinar-x dan scanning electron microscope.  Pola difraksi sinar-x menunjukkan intensitas puncak-puncak difraksi yang tajam dan tinggi mengindikasikan pembentukan material kristalinitas tinggi.  Analisis parameter-parameter struktur menghasilkan nilai yang bersesuaian dengan struktur wurtzite dari seng oksida.  Partikel-partikel berbentuk bulat dengan ukuran 100 nm teramati pada citra electron microscope. Analisis mikrostruktur mengindikasikan bahwa seng oksida kristalin berhasil disintesis. Ekstrak daun anting-anting potensial sebagai bahan alami untuk sintesis oksida logam