Norman Syakir

Characteristic of Thermally Reduced Graphene Oxide as Supercapacitors Electrode Materials

We investigated graphene like material named reduced graphene oxide (RGO) as an electrode material by employed graphene oxide (GO). Thin film of GO was prepared on the indium thin oxide (ITO) substrate by spin-coating method using varied concentration of GO that dispersed in water. In order to remove its oxygen contained, GO film was thermally reduced at 200 °C for 1 hour. We used cyclic voltammetry to measure its CV characteristic and estimated its specific capacitance. We obtained the highest specific capacitance of 6.53 mF g−1 that measured from 4 mg ml−1 RGO thin film at scan rate 25 mVs−1.

Performance of supercapacitor device model based on double layer reduced graphene oxides films as electrodes in KCl electrolyte

We report the performance of supercapacitor device model based on double layer reduced graphene oxide (rGO) films as electrode in 1 M KCl. Graphene oxide (GO) films were deposited on ITO-glass use an electrochemical deposition method using 1 mg/ml GO dispersed in water. The films thicknesses were controlled by number deposition cycles. rGO films were obtained by thermally reduced the GO films at 200°C for 1 hour under argon flowing. A pair of 1 cm2 rGO/ITO electrodes was employed as double layer electrodes of supercapacitor device model using a filter paper which was soaked in 1 M KCl as a separator. Performance of the supercapacitor model was investigated using cyclic voltammetry (CV) in a voltage range of 0.0 volts to +0.9 volts with varied scan rate range of 25mV/s to 125mV/s. The highest specific capacitance of 20 F/kg and specific power of 0.825 W/kg was obtained using device with rGO films that deposited for three voltage cycles.

Effect of KOH concentration on characteristics of polydimethylsiloxane synthesized by ring opening polymerization method

Polydimethylsiloxane (PDMS) that widely known as silicone oil is commonly used as vitreous humour substitutes in vitreoretinal surgery. PDMS is needed to be produced in Indonesia and should be provided with sufficient quantity and quality for domestic needs. We synthesized PDMS using ring-opening polymerization method from octamethylcyclotetra-siloxane as monomer, hexamethyldisiloxane as chain terminator, and KOH as catalyst. KOH concentrations are varied from 0.5 M to 2.5 M to study the effect of KOH concentration on characteristics of PDMS. PDMS We successfully synthesized PDMS with a yield in between 39.73% and 65.30% and various viscosities in the range between 0.58 Pa.s and 9.36 Pa.s. From FTIR spectroscopy, it is found that all synthesized samples have structure and functional groups similiar with that of commercial PDMS. From UV-Vis and refractometer measurements, all samples have transparency almost 100% and refractive indexes in the range of 1.3989 to 1.4039. The effect of KOH concentration on the synthesized PDMS gel is on its viscosity, the higher concentration of KOH, the higher viscosity of the obtained PDMS.

Effect of light exposure on the μSR asymmetry of graphene oxide film

Graphene has received a lot of attention due to its promising properties for electronic devices application such as energy storage device. Due to the amount needed for application, graphene oxide is widely used as a precursor to obtain graphene-like material. The GO film is thermally reduced or photoreduced to obtain graphene-like that known as reduced graphene oxide (rGO). We intend to measure microscopic intrinsic charge carrier motion of GO film by means of muon spin rotation relaxation (μSR). We prepared thick film of GO by stacking a lot of GO sheets using 4 mg/ml GO-water dispersion. The rGO material was obtained by thermally reduced GO film at 200°C for 2 hours under argon flowing. We measured zero field (ZF) μSR measurements of GO and rGO from 10 K and 300 K. During the μSR measurement we exposed the light into the samples. We discuss the effect of light exposure on the μSR asymmetry and compare to μSR asymmetry of rGO sample.

Self-Assembly of ZnO-Nanorods and Its Performance in Quasi Solid Dye Sensitized Solar Cells

Zinc oxide (ZnO) nanorods (NRs) were successfully prepared by self-assembly methods using zinc nitrate hexahydrate and hexamethylenetetramine as raw materials. ZnO-NRs were grown on FTO/ZnO seed layer and to enhance dye adsorption it was continued by deposition of titania (TiO2) paste by screen printing method. Deposition time of ZnO-NRs were varied, for 120, 150 and 180 minutes and subsequently stacked with one layer of TiO2 mesoporous. The resulting heterojunction layers of FTO/ZnO-Nrs/TiO2 was then applied as a photoanode in quasi-solid dye sensitized solar cell (QS- DSSC) with polymer gel electrolyte (PGE) as a hole conductor. UV-Vis spectrometer was used to investigate the changes of dye adsorption in photoanode with/without inserting titania mesoporous. Characterizations of scanning electron microscopy (SEM) and X-ray diffraction was carried out and the results shows that increasing the deposition time produces a smaller average grain size, diameter and denser layer of ZnO-nanorods. From current-voltage measurement, higher efficiency (η = 2.53%) was obtained for 120 min ZnO nanorods with short circuit current density (Jsc ) of 2.84 mA/cm2 and open circuit voltage (Voc) of 0.7 V. The combination of TiO2 and ZnO-NRs shows a better performance in solar cells characteristics due to increases of dye adsorption on photoanode and high photogenerated electron transport rate. This work emphasizes an optimum condition of ZnO-NRs in combination with TiO2 mesoporous as an alternative photoanode in QS-DSSC.

Modification of Blue LED using Organic-Inorganic Hybrid Polymer Doped with Nile Red for Artificial Lighting of Photosynthesis

The photosynthesis process of chlorophyll absorbs only the light with wavelength in the blue and red ranges. The absorption peak of the chlorophyll-A is at 428 nm and 660 nm, while absorption peak of chlorophyll-B is at 453 nm and 643 nm. We report the modification of blue LED using hybrid polymer doped with Nile Red. In order to match the total absorption spectra of chlorophyll-A and chlorophyll-B, the emission spectrum of the modified blue LED was taken out by using the wavelength conversion material. We modified the blue LED by covering the blue LED of 450 nm as excitation source with precursor of red wavelength conversion material. The red wavelength conversion material was prepared by doped precursor of TMSPMA hybrid polymer with organic phosphor of Nile Red. The precursor of hybrid polymer was synthesized using sol-gel process and then it was doped with 0.1% Nile Red. In order to freeze the precursor of these conversion material, we employed UV photopolymerization process. The modified blue LED has two emission peaks, which are at 448 nm (blue emission) and at 651 nm (red emission). The optimum spectrum profile of the modified blue LED has similar range as the total absorption spectra of chlorophyll-A and chlorophyll-B that obtain using Nile Red with the mass of 2.9 μg and the driven current of 60 mA. This result has a potential application for the artificial lighting in the photosynthesis process of horticultures at indoor plantation.

Zinc Oxide/TiO2 Bilayer Heterojunction as a Working Electrode in Quasi Solid Dye Sensitized Solar Cells

Bilayer heterojunction of aluminium doped zinc oxide (AZO) and titanium dioxide (TiO2) mesoporous has been successfully deposited on fluorine tin oxide (FTO) substrate as working electrode in dye sensitized solar cell. This layer was used as working electrode in quasi solid dye sensitized solar cell. The solar cell structure is FTO/ZnO/TiO2/PGE/Pt/FTO using polymer gel electrolyte (PGE). In polymer gel electrolyte system, hybrid copolymer based on poly-TMSPMA (3-methoxysilyl propyl methacrylate) was used as a matrix to trap ionic liquid. An addition of aluminum as atom dopant also studied to observe the physical properties changes of photoanode related to solar cell performance. AlCl3 was used as dopant material with the concentrations at 0.5 weight % and 1.0 weight% of zinc acetate dehydrate as raw material. Based on our previous result, the existence of Al dopant would decrease the surface roughness of ZnO layer, reduce the grain size of ZnO particles, transmittance at visible light increase and also change the charge carrier density. Nevertheless, the highest efficiency was achieved for undoped ZnO/TiO2 photoanode (η=0.67%). Based on current-voltage measurement data analysis (using diode model equation) the ideality factor (n) of device using undoped ZnO was smaller (n=2.96) than AZO 0.5 wt% and 1.0 wt% (n=~4), indicate better quality of undoped ZnO/TiO2 interfaces rather than AZO/TiO2.

KARAKTERISRIK KRISTAL dan OPTIK NANOPARTIKEL ZINC OXIDE: KAJIAN EFEK MOLARITAS dalam PROSES HIDROTHERMAL

Abstrak Sintesis nanopartikel Zinc Oxide (ZnO) dengan metode hidrothermal sangat dipengaruhi oleh beberapa parameter, salah satu diantaranya adalah perbandingan prekursor dan katalis dalam pelarut. Dalam penelitian ini telah berhasil disintesis nanopartikel zinc oxide dengan metode hidrothermal. Prekursor yang digunakan adalah zinc acetat dan katalis NaOH dalam pelarut ethanol. Perbandingan molaritas prekursor dan katalis adalah 0,008:0,5 dan 0,3:0,9. Karakteristik optik, morfologi dan struktur kristal nanopartikel ZnO masing-masing dilakukan dengan pengukuran UV-Vis, TEM dan XRD. Nanopartikel yang dihasilkan memiliki memiliki struktur kristal hexagonal wurtzite. Nanopartikel zinc oxide dengan perbandingan 0,3:0,9 memiliki karakteristik yang paling baik dibandingkan dengan nanopartikel dengan perbandingan 0,008:0,5. Reaksi dalam hidrothermal kaitannya dengan perubahan tekanan akibat peningkatan volume akan dikaji lebih jauh. Kata-kata kunci: oksidasi zinc, nanopartikel, hidrotermal, molaritas Abstract Synthesis of Zinc Oxide (ZnO) nanoparticles by hydrothermal method is influenced by several parameters one of them is the ratio of the precursor and catalyst in a solvent. In this study, we have successfully synthesized of zinc oxide nanoparticles by hydrothermal method. The raw material of precursor is zinc acetate, NaOH as catalyst and ethanol as a solvent. The molarity ratio of precursor and catalyst are 0.008: 0.5 and 0.3: 0.9. The optical characteristics, morphology and crystal structure of ZnO nanoparticles were characterised by the UV-Vis, TEM and XRD, respectively. From XRD measurement, it was observed that samples have hexagonal wurtzite structure and all peaks are well fitted with JCPDS:36-1451 data. The growth condition in the ratio of 0.3: 0.9 showed the best sample with high quality crystal structure and rod form. The effect of molar ratio to the characteristics of nanoparticle will be studied further in relation with the change of volume, and pressure inside of the reactor. Keywords: zinc oxide, nanoparticle, hidrotermal, molaritas

DESAIN LVDT SEBAGAI TRANSDUCER PENGUKUR TEBAL FILM TIPIS

Linier Variable Deference Transformer (LVDT) adalah salah satu transducer yang dapat digunakan untuk pengukuran tebal profil film tipis menggunakan metode Stylus-Elektromekanis. Untuk menerapkan metoda tersebut diperlukan suatu instrumentasi yang terdiri dari perangkat keras dan perangkat lunak. Perangkat keras akan mengolah fluktuasi sinyal analog akibat gerak stylus diatas sampel film tipis yang dikopel pada ferit sebagai inti transducer LVDT, kemudian mengubahnya menjadi sinyal digital. Selanjutnya sinyal digital ini direkam ke dalam komputer melalui fasilitas akusisi data. Perangkat keras dirancang berdasarkan domain waktu. Perangkat lunak dirancang untuk melakukan akusisi data, mengolahnya, berikut intepretasi kuantitatifnya. Oleh karenanya sistem instrumentasi pengukur tebal profil film tipis ini dibuat dilengkapi pula dengan berbagai submenu yang diperlukan, sehingga seluruh proses mulai dari akusisi data sampai dengan intepretasinya dapat dilakukan secara bersamaan. Sensitivitas dari pengukuran bergantung dari parameter geometri tarnsducer LVDT yaitu, panjang dan luas penampang kumparan, jumlah lilitan, karakteristik osilator eksitasi dan stylus. Dalam riset ini, didesain untuk sensitifitas optimalnya 2,5mV/1,5 m m. Alternatif untuk meningkatkan sensitivitas yaitu merubah panjang kumparan menjadi 1-mm, dengan ini akan didapat sensitivitas optimal 2,5 mV/0,5 m m. Cara ini masih terus diuji coba .

Karakterisasi Poli(3-(Trimethoxysilyl)propyl methacrrylate)) yang dimodifikasi dengan Inhibitor Cerium Sebagai Bahan Proteksi Korosi Baja Karbon

Korosi merupakan peristiwa pengrusakan logam akibat bereaksi secara kimia dengan lingkungan sehingga menimbulkan kerugian. Dalam upaya mencegah terjadinya korosi pada material baja karbon API 5L X65, maka dilakukan proses pelapisan dengan menggunakan Poli(3-(Trimethoxysilyl)propyl methacrrylate)) . Poli (TMSPMA) merupakan bahan yang berpotensi untuk memproteksi material dari korosi. Untuk itu ditambahkan inhibitor Cerium Nitrate Hexahydrate , penambahan inhibitor ini bertujuan untuk membuat lapisan proteksi bersifat aktif dan pasif, sehingga ketika lapisan yang bersifat pasifnya rusak masih ada bagian aktifnya yang melindungi material. Bahan prekursor polimer hibrid dibuat dari monomer TMSPMA murni dan yang dicampur inhibitor dengan teknik sol-gel . Hasil yang didapat terbentuknya gel kental yang bening dan menghasilkan yield sebesar 89,58%. Prekursor polimer hibrid yang diperoleh kemudian dikarakterisasi dengan FTIR untuk melihat gugus fungsinya, dengan cara bahan prekursor tersebut dilapiskan pada substrat silikon, hasil karakterisasi FTIR menunjukkan adanya gugus anorganik dan organik yang mengalami polimerisasi. Selanjutnya prekursor polimer hibrid dilapiskan pada baja karbon kemudian dikarakterisasi dengan metoda Potensiostat untuk mengetahui arus korosinya, hasil yang diperoleh menunjukkan penurunan arus korosi dari 1,868 mm/th menjadi 0,02 mm/th