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.

This research investigated the effect of synthesis pH on the microstructure and morphology of the zinc oxide (ZnO) particles prepared using pineapple (Ananas comosus) peel extract. In this study, ZnO powder were synthesized at different pH, i.e. 8, 9, 10, 11, and 12. ZnO samples were characterized using UV-Vis spectroscopy, Fourier Transform InfraRed spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The UV-Vis absorbances spectroscopy shows the optical absorption peak of the ZnO sample occurred in a wavelength range of 300-360 nm, with bandgap energy of ∼3.22 eV. The FT-IR spectrum shows the peak of Zn-O absorption at the wavenumber of 437.55 cm-1 and the reduction of aromatic compounds with increasing of pH. The micrograph of ZnO particles synthesized at different pH shows that the pH affected the size and shape of ZnO. Micro-sized particles with a granular shape have been found at pH 8, and 9, a spherical shape have been found at pH 10, while micro-sized flower-shaped particles have been found at pH 11 and 12. The XRD pattern reveals a wurzite hexagonal ZnO crystal phase with the hkl plane of (101) as the strongest peak, as well as the purity of the sample increasing as the pH value rises. As the conclusion, synthesis pH has a significant impact on the optical, structural, and morphological properties of ZnO biosynthetic powder.

Bio-fabrication of ZnO films using plants, enzymes, and microorganisms has been recognized as an environmentally friendly procedure as an alternative to physical and chemical methods. In this research, the optical and structural properties of ZnO thin film have been investigated using UV-Vis spectrophotometer, X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM), respectively. The ZnO films was prepared by spin-coating the mixed solution of Zn(NO3)2 and watermelon (Citrullus lanatus) peel extract on glass substrate. The ZnO films were then annealed at 400°C for 3h. The UV-Vis absorbance spectra show the strong absorption peaks occurs over a range of wavelengths of 220-380nm, and 190-235 nm for pre-annealed and annealed samples, respectively. The optical band gap of the samples was influenced by the heat treatment. The as-prepared samples synthesized at pH 8 is 3.73 eV and increased up to 5.4 eV after annealed at 400 °C for 3 h. This result suggested that pre-annealed sample has better photocatalytic activity compared to the annealed samples. The XRD pattern of the ZnO films exhibits the ZnO diffraction peaks that correspond to the hkl of hexagonal wurtzite structure. SEM image shows that the morphology of ZnO samples are spherical and rod-like microstructure.

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.

Pristine ZnO and selenium doped ZnO (Se-ZnO) nanorods were successfully synthesized using seed-mediated hydrothermal method. The growth solution of both pure and Se-doped ZnO nanorods employed zinc nitrate hexahydrate (ZNH) and hexamethylenetetramine (HMT) as a precursor and surfactant, respectively. As a dopant source, selenium salt solution was obtained by reacting selenium powder with sodium borohydride at low temperature. The as-prepared pure ZnO and Se-doped ZnO nanorods were characterized using field effect scanning electron microscopy (FESEM), X-ray diffraction (XRD), UV-Visible spectroscopy (UV-Vis), and Photoluminescence (PL) spectroscopy. FESEM images show that the geometric shape of Se-ZnO nanoparticles is nanorods with a hexagonal cross-section. The XRD pattern shows the diffraction peak of the sample at the angles of 2θ: 34.44°, 36.25° and 47.54° which represents the hkl plane of (002), (101) and (102), respectively. The crystalline size calculated from XRD data is found to be in the range of 35-42 nm. The UV-Vis spectrum shows that Se-ZnO nanorods strong absorption peaks appeared in the range of 300-380 nm for all samples. Se doping has slightly altered the band gap energy of pure ZnO nanorods around 0.01 eV. The peak of the photoluminescence spectra of the sample at 470 nm indicates the blue emission band.