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Abstrak :
Nanorod Seng Oksida (ZnO) dengan pemberian variasi doping tunggal Mg sebesar 0%, 1%, 4%, 7% dan 10% disintesis di atas substrat kaca tranparan berlapis indium tin oxide (ITO). Dalam penelitian ini, benih nanorod ZnO dideposisi dengan waktu 10 menit menggunakan metode ultrasonic spray pyrolisis dan ditumbuhkan selama 2 jam dengan metode hidrotermal. Hasil karakterisasi FE-SEM menunjukkan terbentuknya nanorod ZnO dengan ukuran yang beragam dan arah tumbuh yang mayoritas acak. Hasil spektroskopi UV-Vis menunjukkan nilai absorbansi yang cukup tinggi di daerah panjang gelombang ultraviolet. Pemberian doping Mgterbukti mampu meningkatkan nilai lebar celah pita energi meskipun hasil yang didapatkan pada penelitian ini cukup jauh dari nilai lebar pita teoritis (~3.37 eV).

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Zinc Oxide (ZnO) nanorods were grown on the transparent indium tin oxide (ITO) with the variation of Magnesium (Mg) doping (0%, 1%, 4%, 7% and 10%). In this study, ZnO nanoseeds were deposited in 10 minutes using ultrasonic spray pyrolisis method and were grown for 2 hours using hydrothermal method. The characterization of surface morfology using field emission scanning electron microscopy (FESEM) exhibits ZnO nanorods with various diameter and random growth direction. The optical properties were studied through UV-Vis and shows high absorption in ultraviolet spectrum area.Mg dopant could increase the bandgap of ZnO nanorods, though it’s still lower from the theoritical bandgap (~3.37 eV).

Abstrak :
Struktur nano ZnO merupakan salah satu material semikonduktor yang banyak diteliti untuk diaplikasikan dalam devais optoelektronik, fotokatalis dan sensor. Dalam penelitian ini dilakukan proses sintesis nanorod ZnO diatas substrat kaca yang terdiri dari dua tahap yaitu proses pembenihan dengan metode ultrasonic spray pyrolysis dan proses penumbuhan nanorod ZnO dengan metode hidroterma l dengan bantuan gelombang mikro. Fokus penelitian ini adalah mengamati pengaruh konsentrasi bahan penumbuh hexamethyelenentetramine dan zinc nitrate tetrahydrate 0,05 M, 0,1 M dan 0,15 M. Dari hasil SEM, XRD dan UV-Vis menunjukkan bahwa penambahan konsentrasi larutan penumbuh mengakibatka n peningkatan parameter kisi, volume unit sel, ukuran kristalit dari 268 menjadi 426 hingga diameter nanorod dari 89-183 nm menjadi 118-216 nm, serta peningkatan band gap dari 3,20 eV menjadi 3,22 eV. Larutan penumbuh dengan konsentrasi 0,15 M merupakan konsentrasi prekursor terbaik karena dapat menghasilkan absorbansi ultraviolet yang paling tinggi.

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ZnO nanostructure is one of the most studied semiconductor materials for optoelectronic devices, photocatalysts and sensors applications. One way to accelerate the reaction is using microwaves. In this research, ZnO nanorods were grown on glass substrates via seeding process via ultrasonic spray pyrolysis method and growth process via hydrothermal method. The focus of this study is to observe the effect of growth solution concentration of hexamethyelenentetramine and zinc nitrate tetrahydrate 0,05 M, 0,1 M and 0,15 M on the morphology, microstructure and optical properties of ZnO nanorods. By using Scanning Electron Microscoupe SEM, x ray diffraction XRD and UV VIS spectrometers it is seed that an increase of growth solution concentration resulted in the increases of lattice parameters, unit cell volume, crystallite size of 268 to 426 , and diameter of ZnO nanorods from 89 183 nm to 118 216 nm. And also increase the band gap from 3,20 eV to 3,22 eV. Growth solution with a concentration of 0.15 M is the best precursor concentration as it could produce the highest ultraviolet absorbance.

Abstrak :
Optimalisasi kinerja untuk anoda baterai lithium-ion (LIBs) dapat dilakukan dengan mencampur ZnO-nanorods dengan ketentuan Karbon Aktif. Dalam penelitian ini, ZnO-nanorods di sintesis melalui suatu proses yang menggunakan bahan dasar HMTA dan Zinc Oxide. Untuk mengatasi masalah ini karbon telah diaktifkan karena memiliki sifat konduktivitas yang baik dan dapat mempengaruhi volume yang terjadi. Variasi dalam persentase nanorods ZnO yang 4wt%, 7wt%, dan 10wt%. Karakterisasi sampel diperiksa menggunakan X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), dan Brunauer-Emmett-Teller (BET). Kinerja baterai sampel diperoleh dengan Electrochemical Impedance Spectroscopy (EIS), Cyclic Voltammetry (CV), dan Charge-Discharge (CD) pengujian setelah dirangkai menjadi baterai sel berbentuk koin. Penelitian ini membahas tentang pengaruh penambahan karbon aktif terhadap komposit nanorod ZnO. Hasil penelitian menunjukkan bahwa nanorod AC-10%/ZnO-7% memiliki kapasitas spesifik tertinggi 270,9 mAh/g. Menurut tes Brunner-Emmet-Teller (BET), luas permukaan terbesar adalah 631.685 m2/g. Kinerja elektrokimia paling baik diperoleh oleh nanorods AC-10%/ZnO-7%.

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Performance optimization for lithium-ion battery anodes (LIBs) can be done by mixing ZnO-nanorods with the provisions of Active Carbon. In this study, ZnO-nanorods synthesized a process that uses basic ingredients HMTA and Zinc Oxide, in addition. To solve this problem, carbon has been activated because it has good conductivity properties and can affect the volume that occurs. Variations in the percentage of ZnO nanorods which are 4wt%, 7wt%, and 10wt%. Characterization of the samples was examined using X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Brunauer-Emmett-Teller (BET). The battery performance of the samples was obtained by Electrochemical Impedance Spectroscopy (EIS), Cyclic Voltammetry (CV), and Charge-Discharge (CD) testing after being assembled into coin cell batteries. This study discusses the effect of adding activated carbon to ZnO nanorods composites. The results showed that the AC-10%/ZnO-7% nanorods have the highest specific capacity of 270.9 mAh/g. According to Brunner-Emmet-Teller (BET) test, the largest surface area was 631.685 m2/g. Electrochemical performance is best obtained by AC-10% / ZnO-7% nanorods.

Abstrak :
Mikrokantilever (MC) telah banyak dipelajari untuk aplikasi sensor gas karena respon yang cepat, sensitivitas tinggi dan dapat dioperasikan pada suhu kamar. Agar dapat mendeteksi molekul gas karbon monoksida (CO) secara selektif, Al-doped ZnO nanorod (AZNR) dilapiskan pada permukaan MC (AZNMC). Pada disertasi ini, respon mikrokantilever yang dilapisi oleh ZnO nanorod terdoping Al terhadap gas CO diinvestigasi melalui perubahan frekuensi resonansi AZNMC. Selain itu, efek uap air terhadap adsorpsi CO dan sensitivitas sensor juga dipelajari. Pada penumbuhan ZnO nanorod, seed (benih) ZnO dilapiskan pada permukaan mikrokantilever dengan teknik pelapisan dip-coating dan RF sputtering, lalu ZnO rod ditumbuhkan dengan teknik hidrotermal. Dengan menggunakan teknik dip-coating, ZnO rod tumbuh dengan kerapatan sangat rendah (sekitar 16 rod/ mm²) di permukaan MC. Di sisi lain, dengan teknik RF sputtering, ZnO nanorod tumbuh secara vertikal dengan kerapatan tinggi (sekitar 333 rod/ mm²) di permukaan MC pada kondisi pertumbuhan hidrotermal 60 °C selama 2 jam. Pada percobaan awal uji efek gas, ZnO mikrorod (ZMR) dilapiskan pada MC (ZMRMC) untuk mempelajari respon terhadap CO pada udara lembab. Pengukuran frekuensi resonansi ZMRMC ketika diberikan gas CO dilakukan dalam dua kondisi, yaitu, dengan air flushing (kaya uap air) dan tanpa air flushing (lebih sedikit uap air) yang memompa udara ke dalam chamber eksperimen. Hasil penelitian menunjukkan bahwa terdapat perbedaan pergeseran frekuensi resonansi ZMRMC pada dua kondisi tersebut. Pada kondisi dengan air flushing, frekuensi resonansi menurun dan pada kondisi tanpa air flushing, frekuensi resonansi meningkat dengan adanya paparan gas CO. Sensitivitas didapatkan sekitar 9 fg/Hz. Selanjutnya, sebuah model berbasis kombinasi molekul air-CO diusulkan untuk menjelaskan hasil ini. Untuk meningkatkan respon terhadap gas CO, aluminium (Al) atom di-doping pada ZnO nanorods dengan metode sputtering. Hasilnya, deteksi CO dengan AZNMC pada suhu kamar telah sukses dilakukan untuk pertama kali dengan peningkatan sensitivitas sekitar 7 fg/Hz. Meskipun AZNMC juga dapat mendeteksi gas senyawa karbon lainnya, seperti CO₂ dan CH₄. Sensitivitas tertinggi didapatkan untuk gas CO. Adanya atom doping Al pada ZnO mungkin menjadi penyebab interaksi yang kuat antara ZnO nanorods dan CO, sehingga sensitivitas terhadap CO meningkat. Karena deteksi gas dengan menggunakan oksida logam dipengaruhi oleh kelembaban dalam kondisi ambien, maka efek uap air terhadap deteksi CO dan sensitivitas sensor dipelajari pada berbagai kondisi kelembaban relatif. Diketahui bahwa energi adsorpsi memainkan peran yang sangat penting pada adsorpsi CO, sehingga menyebabkan peningkatan sensitivitas sensor. Selain itu, model untuk deteksi CO pada permukaan AZNR juga diusulkan untuk menjelaskan fenomena adsorbsi CO. Pada observasi Signal-to-noise ratio (SNR), didapatkan puncak sinyal dengan intensitas yang sangat tinggi dengan SNR~10³ yang menunjukkan sinyal yang sangat bagus dan dapat dipercaya. Hasil riset ini mengindikasikan bahwa mikrokantilever yang dilapisi ZnO nanorod terdoping Al memiliki kontribusi di masa depan untuk pengembangan detektor CO yang sangat sensitif dengan respon cepat dan dapat beroperasi suhu kamar.

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A microcantilever (MC) is a promising tool for gas sensors due to its rapid response, high sensitivity and operation at room temperature. For sensor application, a sensitive layer is generally coated to effectively detect a target molecule. To selectively detect carbon monoxide (CO) detection, Al-doped ZnO nanorod (AZNR) was coated on the MC surface (AZNMC). In this research, response of the AZNMC toward the gas was investigated by its resonant frequency shift. Moreover, effect of water vapor to CO adsorption and sensor sensitivity was studied. In the Zinc Oxide (ZNR) growth process, a seed layer was grown by hydrothermal method with dip-coating and RF sputtering coating technique. For the dipped seed layer, micro-sized rods with very low density (around 16 rod/ mm²) grew on the MC surface. On the other hand, vertically-alligned ZnO nanorods with high density (around 333 rod/ mm²) grew on the MC surface for the sputtered-seed layer at the growth condition of 60 °C for 2 hours. At initial performance test of gas effect, ZnO microrod (ZMR) was coated on the MC surface (ZMRMC) to study the MC response due to CO insertion in humid air. The measurement of resonant frequency of ZMRMC vibrations due to the CO gas was carried out in two conditions, that is, gas flow with (rich water vapor) and without (poor water vapor) air pumping into an experiment chamber. The results showed that the tendency for resonant frequency shift of ZMRMC due to CO in rich and poor water vapor conditions was different. At the first condition with air pumping, the resonant frequency decreased and at the second condition, the resonant frequency increased to CO exposures. The sensor sensitivity was about 9 fg/Hz. A water molecule-CO combination-based model was proposed to explain those results. To increase the response toward CO, aluminium (Al) atom was doped on the ZnO nanorods (AZNR) by sputtering method. We firstly succeeded to detect CO by using AZNMC at room temperature. A remarkable improvement of the CO gas sensing response of around 7 fg/Hz was observed. The MC with AZNR also detected other carbon compound gases, i.e., CO₂ and CH₄ gases. However, the highest sensitivity was observed for CO gas compared to CO₂ and CH₄ gases. The presence of Al atoms in ZnO is likely to be responsible for strong interaction between CO and Al-doped ZnO nanorods, enhancing the sensitivity to CO. Since the gas detection using a metal oxide was found to be influenced by humidity in the ambient condition. In this work, the effect of water vapor on CO detection and sensor sensitivity was investigated at varied relative humidity conditions. It was found that the surface energy plays a very important role on CO adsorption and causes the increase of sensor sensitivity. A model for CO detection through the AZNRs surface has been proposed to explain the CO adsorbing phenomenon. In Signal-to-noise ratio (SNR) observation, the very high intensity signal peaks with SNR of the order of 10³ indicated that the signal was excellent and trusted. These findings may contribute to future developments of highly sensitive toxic-CO-gas detectors with a fast response and room temperature operations without a device heating.

Abstrak :
ZnO merupakan salah satu semikonduktor yang menarik untuk dikembangkan sebagai fotokatalis untuk mengolah zat pewarna tekstil menjadi produk yang kurang berbahaya. Pada penelitian ini disintesis ZnO nanorod diatas substrat kaca dengan metode Ultrasonic Spray Pyrolysis dan hydrothermal. Untuk meningkatkan aktivitas fotokatalitiknya, nanorod ZnO diberi doping unsur Mn dengan lima konsentrasi yang berbeda 0, 1, 3, 5 dan 7 mol. Hasil karakterisasi dengan menggunakan FESEM, XRD, XPS, Spektroskopi Raman, Spektrofotometer UV-Vis dan Photoluminescence menunjukan bahwa penambahan unsur Mn dapat memperbesar luas permukaan nanorod ZnO, meningkatkan kristalinitas dan cacat kristal khususnya kekosongan O. Hal ini menyebabkan aktifitas fotokatalitiknya dapat meningkat. Penambahan unsur Mn 7 menghasilkan degradasi metil biru tertinggi yaitu 76,75 dalam waktu 38 menit.

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ZnO is one of the interesting semiconductors to be developed as a photocatalyst to process the textile dyes into less harmful products. In this study, ZnO nanorod was synthesized on glass substrate by ultrasonic spray pyrolysis and hydrothermal methods. In order to improve the photocatalytic activity, ZnO nanorods were doped with Mn element with 5 different concentrations 0, 1, 3, 5 and 7 mol. The characterization results using FESEM, XRD, XPS, Raman Spectroscopy, UV Vis Spectrophotometer and Photoluminescence show that the addition of Mn element can increase the surface area of ZnO nanorod, crystallinity and crystal defect especially vacancy O. This causes the photocatalytic activity was increased. The addition of Mn 7 element resulted in the highest methyl blue degradation of 76.75 within 38 minutes.

Abstrak :
Zinc oxide (ZnO) nanorods have been considered as a potential semiconductor oxide material for the application of dye-sensitized solar cells (DSSC). Various experiments have been conducted to improve its nanostructural characteristics and functional properties in order to make it well suited for enhancing DSSC’ performance. Inspired by such studies, the ZnO nanorods array was grown on indium tin oxide (InSn2O3, ITO) substrate in the present work. For this purpose, a seed solution was prepared at low temperature (0oC) using zinc nitrate tetrahydrate and hexamethylenetetramine. The ZnO seed layers were deposited onto ITO glass using a spin-coating technique and further annealed at two different temperatures, 200 and 400 oC. The seeding was also varied between one, three and five layers, prior to the growing process using the chemical bath deposition method (CBD). The results showed that the annealing temperatures significantly influenced the ZnO nanorods’ growth. The optimal condition was achieved by using three seed layers annealed at 200oC, providing an average diameter of 157.58 nm, the biggest crystallite size (up to 59.63 nm), and a band-gap energy (Eg) of 3.27 eV. Based on the obtained properties, the growth of ZnO nanorods on ITO substrate in this work has the potential to be used for the application of dye-sensitized solar cells.