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In this work, ZnO photocatalyst has been synthesized using matoa (Pometia pinnata) leaf extract under various microwave irradiation powers at 360, 540, and 720 Watts for 3 minutes on each. The UV-Vis absorption spectra of ZnO exhibited a peak in the ultraviolet region 300-360 nm. UV-Vis absorption analysis revealed a decrease in the band gap energy from 3.15 eV to 3.10 eV as the irradiation power increased. Field emission scanning electron microscopy (FESEM) images displayed spherical and nanoplatelet morphology with a decrease in particle size observed from 773 to 709 nm with increasing irradiation power. X-ray diffraction (XRD) analysis confirmed the hexagonal wurtzite structure of ZnO with crystallite sizes in the range of ~18-20 nm. The synthesized ZnO nanoparticles was successfully employed as a photocatalyst in 4-nitrophenol degradation, achieving the highest degradation percentage of 82.7% at 540 Watts with a corresponding reaction rate constant of 0.0126/min. In conclusion, the microwave-assisted synthesis of ZnO using on matoa leaf extract demonstrated significant potential for the degradation of organic pollutants, thereby contributing to water purification efforts.

We report the ZnO/ZnS and ZnO/ZnSe nanocomposites synthesized using the solvothermal-microwave method. Raman analysis was thoroughly studied to explain phonon vibration mode in this paper. The strong intensity confirms the highfrequency phonon mode of hexagonal wurtzite ZnO. Also, the presence of Raman intensity of the cubic ZnS and ZnSe structures indicates the longitudinal optical phonon mode. In addition, we find several slight shifts in all ZnO modes for ZnO/ZnS and ZnO/ZnSe which demonstrate stress and strain in the crystal lattice. We investigate the change in particle size from confocal Raman microscopy. Therefore, the modifications to the material structure and particle size have enhanced its characteristics. Accordingly, the nanocomposite heterostructures by the simple chemical method are attractive materials suitable for optoelectronic devices.

The ZnO nanoparticles were synthesized at various precursor concentrations i.e. 0.05, 0.1, and 0.5 M by biosynthesis method based on Pometia pinnata Leaf Extracts. Initial nanoparticle concentration influenced the optical bandgap, shape, and structure of nanoparticles. The photodegradation process was carried out under UV illumination. The efficiency of MB degradation was determined by measuring the decrease in MB concentration and by analyzing the optical absorption at 663 nm recorded by UV-Vis spectroscopy. Results showed that the biosynthesized ZnO nanoparticles exhibited efficient photodegradation of MB, with a maximum degradation rate of 80% after 90 minutes of exposure to UV-C light. The study highlights the potential of Pometia pinnata leaf extracts as a low-cost and eco-friendly alternative for synthesizing ZnO nanoparticles for use in environmental remediation processes

In this paper, the flower-shaped ZnO particles have been prepared via microwave-assisted biosynthesis technique using an aqueous extract of Sandoricum koetjape peel at various irradiation powers, i.e. 180, 360, 540, and 720 Watt. The synthesized flower-shaped ZnO particles were characterized using UV-Vis spectroscopy, x-ray diffraction (XRD), and field emission scanning electron microscope (FESEM). The UV-vis spectra exhibited ZnO absorption peaks in the UV region with band gap energy in the range of 3.25 - 3.29 eV. XRD analysis confirmed the hexagonal wurtzite crystal with the high purity of ZnO particles. The flower-shaped morphology of ZnO was evident in FESEM images with the decrease of particle diameter as the radiation power increased from 257 to 447 nm. ZnO prepared at 720 Watt (Z-720) succeeded in degrading 4-nitrophenol with the highest efficiency of 84.8 % after 240 min. Consequently, biosynthesis ZnO will have a great opportunity to be applied in degrading wastewater pollutants.

Zinc oxide (ZnO) synthesized with natural reductants has attracted the attention of researchers because it is environmentally friendly and non-toxic. In this study, ZnO was prepared using Sandoricum koetjape (S. koetjape) peel extract. An aqueous extract of S. koetjape peel was used as biological reduction agent for the synthesis of ZnO from zinc nitrate hexahydrate. The ZnO powder obtained was annealed at different temperatures i.e, 300°C, 400°C, and 500°C for 1 hour. Structural, morphological, optical properties, and functional groups of samples were analyzed using X-Ray Diffraction, Scanning Electron Microscopy, UV-Vis Spectroscopy, and Fourier Transform Infrared Spectroscopy, respectively. The X-ray diffraction pattern shows that pure hexagonal wurtzite structure of ZnO particles can be achieved after annealing. The crystal size has also increased with increasing annealing temperature. SEM photo demonstrates the transformation of ZnO particle from spherical to microflower due to annealing. The widest absorption peaks in the UV-Vis spectrum was occurred after annealing at 500°C. The bandgap energy of ZnO increases after annealing from 3.08 eV to 3.20 eV. The FT-IR analysis confirms O-H functional group from extract has been decomposed due to the annealing process. Based on this study, biosynthesized ZnO using Sandoricum koetjape peel extract requires annealing process to improve the purity, enhance the light absorbance and change the microstructure of ZnO.

This study aims to investigate the physical characteristics and photocatalyst activity of biosynthesized ZnO with pineapple (Ananas comosus) peel extract under microwave irradiation. The ZnO powder was prepared in two different concentrations of zinc nitrate hexahydrate (ZNH) at 200mM (Z-200) and 500 mM (Z-500). The optical, structural, and morphological properties of ZnO were analyzed using UV-Vis spectroscopy, X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM), respectively. The UV-Vis absorption spectrum showed a wide absorbance peak of ZnO at the wavelength of 300-360 nm with a bandgap energy of 3.22 and 3.25 eV. The XRD result confirmed the wurtzite structure of ZnO with high crystallinity. SEM morphology showed spherical particles with an average particle size of 190-220 nm. For photocatalytic application, ZnO film was fabricated via the doctor blade method from microwave-assisted biosynthesized ZnO powder. ZnO films were then applied under UV-irradiation to examine the photocatalytic degradation of methylene blue. It was found that the catalytic behavior of ZnO film was affected by the starting ZNH concentration with maximum effectiveness of 46% degradation after 2 h.

Abstrak. Dalam rangka mengurangi pemakaian bahan kimia berbahaya, kini telah mulai dikembangkan penggunaan bahan alami pada proses pembentukan nanopartikel. Pada penelitian ini, biosintesis nanopartikel ZnO dilakukan menggunakan ekstrak kulit Ananas comosus sebagai agen capping sekaligus agen pereduksi. Seng nitrat digunakan sebagai prekursor dari ion seng, sedangkan kulit nanas dibuat menjadi ekstrak untuk dimanfaatkan kandungan antioksidannya. Sampel ZnO dipelajari sifat fisisnya dari hasil karakterisasi X-ray diffraction (XRD), scanning electron microscopy (SEM) dan spektroskopi UV-Vis. Berdasarkan pola XRD, nanopartikel ZnO memberikan fasa kristal heksagonal wurtzite dengan ukuran kristal 14 nm. Morfologi SEM masing-masing sampel didapatkan berbentuk bunga atau micro-nanoflower dengan ukuran diameter rata-rata 510 nm dan 560 nm untuk sampel 0,01 M dan 0,025 M. Hasil spektrum absorbansi UV-Vis menunjukkan peningkatan puncak penyerapan cahaya dengan penambahan konsentrasi seng nitrat. Berdasarkan informasi sifat fisis ini, sampel ZnO berpotensi diaplikasikan sebagai material fotokatalis. Abstract. In order to reduce the use of hazardous chemicals, the use of natural ingredients has now been developed in the process of forming nanoparticles. In this study, biosynthesis of ZnO nanoparticles was carried out using Ananas comosus peel extract as capping agent and reducing agent. Zinc nitrate was used as a precursor to zinc ion. The physical properties of ZnO samples were studied from the characterization result of scanning electron microscopy (SEM), UV-Vis spectroscopy, and X-ray diffraction (XRD). The SEM morphology of each different sample was obtained in the form of micro-nanoflower with an average diameter of 510 nm and 560 nm for 0.01 M and 0.025 M samples, respectively. The UV-Vis absorbance spectrum results showed an increase in the light absorption peak as zinc nitrate concentration increased. According to the XRD pattern, the ZnO nanoparticles possessed an hexagonal wurtzite crystal phase with a crystal size of 14 nm. Based on this information on physical properties, the ZnO sample has the potential to be applied as a photocatalyst material.

Abstrak. Sel surya berbasis perovskite merupakan sel fotovoltaik generasi terakhir yang mampu memanfaatkan energi surya dengan efisiensi tinggi dan dapat difabrikasi melalui proses yang sederhana dan murah. Sejak diperkenalkannya perovskite solar cell (PSC), efisiensi konversi dayanya telah mencapai efisiensi di atas 23% dalam waktu yang relatif singkat diiringi dengan peningkatan publikasi ilmiah di bidang ini. Penggunaan semikonduktor ZnO sebagai Electron Transport Material (ETM) yang merupakan salah satu bagian utama dalam PSC mulai dilirik akibat proses pembuatan yang lebih sederhana dibandingkan TiO2. Seng oksida (ZnO) masih memiliki kelemahan yang dapat diatasi dengan penambahan ZnS untuk mengurangi rekombinasi pembawa muatan dari lapisan perovskite ke ETM. Tujuan dari artikel ini adalah untuk menyajikan tinjauan singkat tentang status terkini mengenai komposit ZnO/ZnS sebagai elektron transport material pada sel surya perovskit. Ulasan ini juga membahas peran penambahan ZnS dalam memperbaiki morfologi dalam ukuran nano dan sifat optik material sekaligus meningkatkan kinerja PSC beserta penjelasan mengenai mekanisme dasar operasi piranti untuk memberikan pemahaman yang lebih baik tentang sifat dari ZnO/ZnS sebagai ETM pada sel surya perovskit. Abstract. Perovskite-based solar cells are the latest generation of photovoltaic cells capable of utilizing solar energy at high efficiency and can be fabricated through a simple and inexpensive process. Since the introduction of the perovskite solar cell (PSC), its power conversion efficiency has reached efficiencies above 23% in a relatively short period of time accompanied by an increase in scientific publications in this field. The use of ZnO semiconductors as Electron Transport Material (ETM), which is one of the main parts of PSC, has begun to be noticed due to the simpler manufacturing process compared to TiO2. Zinc oxide (ZnO) still has a weakness which can be overcome by adding ZnS to reduce the recombination of the charge carriers from the perovskite layer to the ETM. The aim of this article is to present a brief overview of the current status of ZnO/ZnS composites as an electron transport material in perovskite solar cells. This review also discusses the role of addition of ZnS in improving morphology in nanosize and optical properties of materials as well as improving PSC performance along with an explanation of the basic mechanism of device operation to provide a better understanding of the properties of ZnO/ZnS as ETM in perovskite solar cells. Keywords: Perovskite solar cell, Composite, ZnO, ZnS dan Electron Transport Material.