Graphene growth at low temperatures using RF-plasma enhanced chemical vapour deposition

The advantage of plasma enhanced chemical vapour deposition (PECVD) method is the ability to deposit thin films at relatively low temperature. Plasma power supports the growth process by decomposing hydrocarbon to carbon radicals which will be deposited later on metal catalyst. In this work, we have successfully synthesis graphene on Ni and Co films at relatively low temperature and optimize the synthesis conditions by adjusting the plasma power. Low temperature growth of graphene was optimized at 600°C after comparing the quality of as-grown graphene at several temperatures from 400 to 800°C and by varying plasma powers in the range of 20 - 100 W. Raman analysis of the as-grown samples showed that graphene prefers lower plasma power of 40 W. The annihilation of graphene formation at higher plasma powers is attributed to the presence of high concentration of hydrogen radical from methane which recombines with carbon elements on thin film surface. The optimum graphene growth conditions were obtained at growth temperature of 600°C, plasma power of 40 W and growth time of 10 min with methane flow rate of 120 sccm

Synthesis and Characterization of TiO2 Semiconductor Doped by AgNO3 and Their Application as Photoanode in Dye-sensitized Solar Cells

The use of Titanium dioxide (TiO2) semiconductors in Dye-Sensitized Solar Cells (DSSC) devices have been extensively studied and synthesized with various techniques to obtain optimal performance. The TiO2 semiconductors with optimal performance are influenced by the growth method, the time of growth, the shape of the microstructure, and the optical properties. In this study, it was reported about the effect of silver nanoparticles (AgNO3) doping onto TiO2 semiconductors on their microstructure, reflectance, and efficiency of the DSSC device. The synthesis of TiO2 was carried out using liquid phase deposition (LPD) and immersed into an AgNO3 solution with a variation of time namely 0.5 h, 1 h, 2 h, 4 h, and 6 h. The entire TiO2 + AgNO3 sample, then used as a photoanode on DSSC with plastisol as a counter electrode. Characterization of microstructure, reflectance, and DSSC performance was carried out by using field emission scanning electron microscopy (FESEM), Uv-Vis Spectrophotometer, and Gamry Instrument, respectively. The FESEM results show that AgNO3 has successfully grown on the ITO substrate in a spherical shape with an average particle diameter ranging from 1.52-2.29 μm. From observations using the Uv-Vis Spectrophotometer, obtained the energy band gap values ranged from 0.22 to 2.27 eV. The best results of DSSC device efficiency, with TiO2+AgNO3/Dye/Plastisol structure, have resulted in the Voc of 0.694 V, current density (Jsc) of 0,943 mA/cm2and fill factor (FF) of 43,50% which is obtained at sample 1

Pengaruh Lama Penumbuhan Titanium Dioksida Didoping Copper Terhadap Energi Gap

Deposisi lapisan TiO2 didoping Cu telah berhasil ditumbuhkan dengan menggunakan metoda Liquid Phase Deposition (LPD). Lapisan TiO2-Cu dibuat dengan menggunakan material Ammonium hexafluorotitanate ((NH4)2TiF6), Copper (II) Nitrate hydrate (Cu(NO3)2·xH2O), dan Hexamethylen tetramine (C6H12N4). Dalam penelitian ini dilakukan variasi lama penumbuhan lapisan yaitu 3 jam, 5 jam, 7 jam dan 10 jam. Lapisan TiO2-Cu dikarakterisasi menggunakan Spektrometri Ultraviolet-Visible (UV-Vis) untuk menentukan energi gap melalui spektra difusi reflektansi. Hasil energi gap yang diperoleh pada lapisan TiO2-Cu dengan variasi lama penumbuhan yaitu antara 3,26-3,30 eV.Kata kunci: Titanium dioksida (TiO2), Liquid Phase Deposition (LPD) dan dopingÂ

EFFECT OF PREPARATION ACETONE ON FISH BONES SYNTHESIZED THROUGH SINTERING METHOD TO IMPROVE HYDROXYAPATITE CHARACTERISTICS

In the development of advanced materials and various technological applications, the preparation and sintering processes have become two important factors in determining material characteristics. This research focuses on two main aspects, namely the effect of fish bone preparation by soaking in acetone and the surface area of the material in the sintering process as part of the process of developing better materials. This research aims to determine the effect of soaking fish bone powder with acetone and the effect of the surface area of sintered fish bones to produce hydroxyapatite (HA). The immersion process with acetone is included in the sample preparation stage, while the sintering process is included in the material synthesis stage. These two things can affect the characteristics of the HA produced after analysis from the X-ray diffraction test. The HA structure obtained from all samples is hexagonal with cell parameter values a = b ≠ c and space group P 63 / m, where all samples have a value range of a = b = 9,42 Å and c = 6,88 Å. HA crystallinity was identified through the XRD peak at 2θ = 25,8 (002); 31,7 (211); 32,1 (112); 32,8 (300); 34,0 (202); 39,7 (310); 46,6 (222); 49,4 (213); 50,4 (321). The PAF-900 and CAF-900 samples are similar to HA in JCPDS 01-089-4405 whose compound formula is Ca5(PO4)3(OH) while the PWAF-900 sample is similar to HA in JCPDS 01-075-3727 whose compound formula is Ca5(PO4)3(CO3)0.01(OH)1.3. The percentage of crystallinity of PAF-900, CAF-900, and PWAF-900 respectively was 84,767; 73,506; and 71,962% with HA grain sizes of 0,8964; 0,6808, and 0,7398 nm. The HA density of PAF-900 and CAF-900 samples is 3,149 g/cm3 while PWAF-900 is 3,146 g/cm3. Based on this description, it can be concluded that the soaking preparation stage with acetone produces HA with the chemical formula Ca5(PO4)3OH with a higher percentage of crystallization and is denser compared to HA obtained without going through the soaking preparation stage with acetone. The sintering stage also plays an important role in increasing the crystallization percentage. The surface area of the material being sintered also influences the percentage of crystallization and the grain size of the resulting HA. Sintered fish bone powder produces a greater percentage of crystallization and grain size than fish bone chunk

Sintesis Nanopartikel Titanium Dioksida Didoping Rhutenium

Nanopartikel titanium dioksoda (TiO2) yang didoping ruthenium (Ru/TiO2) ditumbuhi dengan menggunakan metode penumbuhan Liquid Phase Deposition (LPD) telah berhasil dilakukan. Konsentrasi doping ruthenium yang digunakan adalah 2,5 mM. Variasi lama waktu penumbuhan dilakukan selama 3 jam, 5 jam, 7 jam dan 10 jam. Kemudian dilakukan karakterisasi Ultraviolet-visible, fotoelektron sinar-x dan teknik difraksi sinar-x. Energi gap yang didapatkan dengan waktu penumbuhan 3 jam dan 5 jam adalah 3,22 eV dan 3,28 eV. Sedangkan waktu penumbuhan 7 jam dan 10 jam adalah 3,16 eV dan 3,29 eV. Morfologi dari Ru/TiO2 bersifat nanopori dengan fasa adalah anatase. Kata kunci: Liquid Phase Deposition (LPD), nanopartikel Ru/TiO2, doping ruthenium, fase anatase.

Synthesis of CdTe-CdSe core-shell quantum dots with luminescence in the red

This paper reports on the synthesis and characterization of CdTe-CdSe core-shell quantum dots (QDs) with luminescent from 650 to 720 nm. The QDs were synthesized using a wet-chemical process at a moderate temperature (300 °C) following two-steps process of core and shell synthesis. The photoluminescence characterization on the QDs showed that the QDs emitted light in the range of red regime with quantum yield as high as 37%. Owing to their unique photoluminescence characteristics (high quantum yield and narrow spectrum), the QDs may find a potential application in a variety of applications such as LED, solar cell and bio-labeling

Gold nanoplates for a localized surface plasmon resonance-based boric acid sensor

Localized surface plasmon resonance (LSPR) properties of metallic nanostructures, such as gold, are very sensitive to the dielectric environment of the material, which can simply be adjusted by changing its shape and size through modification of the synthesizing process. Thus, these unique properties are very promising, particularly for the detection of various types of chemicals, for example boric acid which is a non-permitted preservative employed in food preparations. For the sensing material, gold (Au) nanoplates with a variety of shapes, i.e., triangular, hexagonal, truncated pentagon and flat rod, were prepared using a seed-mediated growth method. The yield of Au nanoplates was estimated to be ca. 63% over all areas of the sensing material. The nanoplates produced two absorption bands, i.e., the transverse surface plasmon resonance (t-SPR) and the longitudinal surface plasmon resonance (l-SPR) at 545 nm and 710 nm, respectively. In the sensing study, these two bands were used to examine the response of gold nanoplates to the presence of boric acid in an aqueous environment. In a typical process, when the sample is immersed into an aqueous solution containing boric acid, these two bands may change their intensity and peak centers as a result of the interaction between the boric acid and the gold nanoplates. The changes in the intensities and peak positions of t-SPR and l-SPR linearly correlated with the change in the boric acid concentration in the solution

Synthesis of Bioplastics on Rice Straw Cellulose Using Orange Peel Extract, Chitosan, and Sorbitol

With the use of several plasticizers (orange peel extract, chitosan, and sorbitol), rice straw cellulose has been used to synthesize and characterize bioplastics. This study aims to synthesize and characterize bioplastics from rice straw cellulose with various additions of plasticizers, namely orange-peel extract, chitosan, and sorbitol, each with a certain concentration so that quality improvement can occur. The methods used in this study include testing the tensile strength value, testing the percentage elongation, and testing the percentage of biodegradation. In addition, functional group characterization tests were also carried out using FTIR. The results obtained in this study were the best values for tensile strength and percentage elongation in treatment A, namely 10.2611 MPa and 13.88%. The percentage of biodegradation for 7 days reached 50.58%. Functional group absorptions were found in various plasticizers, namely C-H, O-H, C-O, C-N, and C=C. Based on existing data, bioplastics synthesized using rice straw cellulose in various plasticizers meet JIS (Japan Industrial Standards)

Synthesis of Bioplastics on Rice Straw Cellulose Using Orange Peel Extract, Chitosan, and Sorbitol

With the use of several plasticizers (orange peel extract, chitosan, and sorbitol), rice straw cellulose has been used to synthesize and characterize bioplastics. This study aims to synthesize and characterize bioplastics from rice straw cellulose with various additions of plasticizers, namely orange-peel extract, chitosan, and sorbitol, each with a certain concentration so that quality improvement can occur. The methods used in this study include testing the tensile strength value, testing the percentage elongation, and testing the percentage of biodegradation. In addition, functional group characterization tests were also carried out using FTIR. The results obtained in this study were the best values for tensile strength and percentage elongation in treatment A, namely 10.2611 MPa and 13.88%. The percentage of biodegradation for 7 days reached 50.58%. Functional group absorptions were found in various plasticizers, namely C-H, O-H, C-O, C-N, and C=C. Based on existing data, bioplastics synthesized using rice straw cellulose in various plasticizers meet JIS (Japan Industrial Standards)

Reka bentuk sensor pendar cahaya bintik kuantum ZnCdSe untuk mengesan racun perosak

Racun perosak digunakan secara meluas dalam sektor pertanian bagi meningkatkan hasil pengeluaran tanaman. Namun demikian, racun perosak boleh memudaratkan kesihatan manusia, haiwan, ikan dan menyebabkan pencemaran alam sekitar terutamanya pencemaran air. Kertas ini melaporkan kajian pembangunan sistem sensor pendar cahaya untuk mengesan kehadiran racun perosak di dalam air dengan menggunakan filem nipis bintik kuantum. Sistem sensor pendar cahaya mempunyai empat bahagian: sumber cahaya untuk menguja racun perosak, kebuk sensor yang mengandungi sampel racun perosak, serat optik yang memandu cahaya daripada sumber ke kebuk sensor dan sistem analisis. Penduga serat optik dupleks berfungsi menyalurkan sumber cahaya penguja dan pancaran. Pada bahagian hujung serat optik terdapat permukaan kaca pada penduga yang dimendapkan dengan filem nipis bintik kuantum ternari ZnCdSe yang disintesis menggunakan kaedah kimia basah pada suhu 350°C dan masa pertumbuhan hablur ZnCdSe adalah 5 min. Pengesanan racun perosak diukur dengan membandingkan spektrum pendar cahaya (PL) filem nipis ZnCdSe di dalam air dan di dalam larutan racun perosak dengan variasi kepekatan 2.5 hingga 2500 μg/L. Pengesanan dalam uji kaji ini menunjukkan spektrum PL filem nipis ZnCdSe menurun apabila dicelupkan ke dalam larutan racun perosak berbanding dengan puncak spektrum di dalam air. Peratus perbezaan penurunan PL meningkat dengan peningkatan kepekatan racun perosak dan bergantung secara linear kepada kepekatan racun perosak