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Abstrak :
Biosensor yang memanfaatkan jaringan SWCNT sebagai transduser dan PDMS sebagai substrat sistem mikrofluida memiliki potensi untuk dikembangkan menjadi biosensor yang memiliki senstivitas tinggi dan mudah dipabrikasi. Penelitian ini bertujuan untuk membuat rangka biosensor yang sensitif terhadap lingkungan elektroniknya. Sensitivitas dari biosensor dapat dicapai dengan mengatur kerapatan jaringan SWCNT dibawah titik perkolasinya, sehingga jaringan SWCNT memiliki sifat semikonduktif. Penelitian ini menghasilkan rangka biosensor dengan tiga variasi kerapatan pada sensornya, dan berdasarkan titik perkolasinya, satu sensor dengan kerapatan rendah memiliki sifat semikonduktif dengan perubahan respon terhadap larutan KCl 3.10-2 M mencapai 90 kali dan dua sensor dengan kerapatan tinggi memiliki sifat logam dengan perubahan respon 1,1 dan 1,04 kali. ......Biosensor that utilizes Single Wall Carbon nanotube(SWCNT) network as transducer and Poly(dimethylsiloxane) (PDMS) as a substrate for microfluidic system has potential to be developed as biosensor that have high sensitivity and fabricated easily. The aim of this research is to make sensitive framework of biosensor against its electronic environment. The sensitivity of biosensor can be achieved by adjusting the density of the SWCNT network below its percolation point, so that it has semiconducting characteristic. From this research, we have created framework of biosensor with three wariations of SWCNT's density, and based on its percolation point, one sensor with low density network have semiconductive characteristic and two sensors with high density network has metallic characteristic. Biosensor framework response to 3.10-2 M KCl solutions increasing electrical current up to 90 times for semiconductive sensor and only 1.1 and 1.04 for metallic sensors.

Abstrak :
Berbagai upaya meningkatkan kapasitas adsorpsi hidrogen pada Carbon Nanotubes CNT banyak dilakukan diantaranya melalui: optimasi struktur, pengaturan unsur doping serta modifikasi pada CNT sehingga diperoleh CNT dengan karakteristik baru, atau material dengan struktur baru. Jenis material nanostruktur yang sekarang banyak menarik perhatian adalah Boron Carbide, Boron Nitride dan Carbon Nitride. Pada penelitian ini model struktur yang dibahas adalah Single-walled Triazine Nanotube SWTNT, SWTNT dengan substitusi Boron, Boron Substituted-Single Walled Triazine Nanotube SWBTNT serta SWTNT substitusi boron dengan doping lithium: Lithium Doped on Boron Substituted Single-walled Triazine Nanotube SWBTLi2NT yang secara struktur maupun aplikasi untuk penyimpanan hidrogen belum banyak dibahas. Pada tahap awal penelitian dilakukan kajian semi empirik untuk mendapatkan diamater optimum untuk menyimpan hidrogen. Diperoleh diameter optimum pada diameter kurang dari 5? atau pada diameter antara 11 ndash; 14 ?. Berdasarkan hasil tersebut selanjutnya dilakukan simulasi adsorpsi hidrogen Single-walled Carbon Nanotube SWCNT dan berbagai material nanostruktur dengan chiralitas 18, 0. Analisa termodinamik yang paling penting dilakukan adalah perhitungan nilai luas permukaan spesifik spesific surface area/SSA. Dari hasil perhitungan berbagai model material diperoleh nilai SSA berturut-turut 2600, 2730 dan 2828 dan 2458 m2/g. Dengan demikian maka dapat diduga modifikasi struktur dengan substitusi/doping logam pada material berbasis karbon akan meningkatkan kapasitas adsorpsi hidrogen. Modifikasi tersebut juga mengidentifikasikan adanya peningkatan energi adsorpsi hidrogen secara signifikan yang besarnya berturut-turut 1,2; 1,97; 2,25 dan 9,7 kkal/mol. Simulasi dinamika mulekular MD memberikan hasil kapasitas adsorpsi pada temperatur ruang berturut-turut sebesar 1,59; 2,17; 2,31 dan 6,31 wt , di tekanan 120 atm. Pada temperatur 233 K kapasitas adsorpsi meningkat menjadi 2,26; 2,96; 3,23 dan 6,82 wt serta 6,1; 6,84; 7,73 dan 8,52 wt pada temperatur 77 K. Untuk memverifikasi hasil simulasi dilakukan perbandingan dengan regresi model adsorpsi isotermal, perbandingan dengan hasil eksperimen, perbandingan dengan perhitungan Density Functional Theory DFT , simulasi Grand Canonical Monte Carlo GCMC serta hasil simulasi MD dari hasil yang telah terpublikasi. Perbandingan dengan perhitungan semi empirik maupun eksperimen, secara umum hasil simulasi lebih tinggi sekitar 10 ndash; 20 . Dengan hasil DFT dan GCMC, hasil MD lebih rendah 10 ndash; 20 dan dengan hasil MD peneliti lain perbedaannya berkisar 5-10. Hasil MD juga menunjukkan adanya kesesuaian dengan model adsorpsi isotermal Langmuir, model isotermal Sips maupun model isotermal Toth dengan nilai koefisien determinasi di atas 0,99 pada temperatur 298 K, di atas 0,95 pada temperatur 233 K dan di atas 0,85 pada temperatur 77 K. Analisa monolayer coverage menunjukkan bahwa tanpa doping lithium daerah yang sanggup dicover tidak melebihi 30 , 40 dan 55 masing-masing pada temperatur 298, 233 dan 77 K. Dengan doping lithium coveragenya naik hingga 300. Dicapai coverage hampir 100 pada temperatur 298, 233 dan 77 K berturut-turut pada tekanan 100, 30 dan 5 atm. Berbagai ukuran termodinamik menunjukkan bahwa tanpa modifikasi sulit bagi SWCNT memenuhi kriteria untuk aplikasi penyimpanan hidrogen. Langkah modifikasi yang dilakukan melalui substitusi dan doping logam merupakan peta jalan yang mengarah untuk didapatkannya material baru yang dapat memenuhi target Departemen Energi Amerika Serikat US DoE . Dengan demikian SWBTLi2NT dapat diusulkan sebagai material jenis baru yang memenuhi berbagai persyaratan untuk aplikasi hydrogen storage. ......Various eff orts have been conducted intensively to increase the hydrogen adsorption capacity of Carbon Nanotubes CNT , such as structure optimization, doping element arrangement and structure modification to obtain new characteristics of CNTs, or newly acquired materials. New types of materials that now attract a lot of attention are Boron Carbide, Boron Nitride and Carbon Nitride. The structural models discussed in this study are Single walled Triazine Nanotube SWTNT, Boron Substituted Single walled Triazine Nanotube SWBTNT and Single walled Triazine Nanotube with substitution of boron and lithium doping SWBTLi2NT which structurally and in application for hydrogen storage has not been much discussed. Based on semi empirical study, it is obtained that the optimum diameter to store hydrogen is diameter less than 5 or diameter between 11 14. From this results, a Single walled Carbon Nanotube SWCNT simulation was performed on chirality 18.0 . The choice of chirality is to assure three dimensional symmetrical properties, when the material type is replaced by a more complex type of material. Based on the results, further simulations were made on various material variations with 18, 0 chirality The first thermodynamic analysis performed was calculation of SSA value and in various models the material obtained the value of SSA respectively of 2600, 2730 and 2828 and 2458 m2 g. Thus it can be predicted that structural modification by substitution and doping on carbon based materials will increase the hydrogen adsorption capacity. The modification also identified a significant increase in hydrogen adsorption energy of 1.2, 1.97, 2.25 and 9.7 kcal mole. The molecular dynamics simulation gives the result of adsorption capacity at room temperature is respectively of 1.59, 2.17, 2.31 and 6.31 wt . At temperature of the adsorption capacity increased to 2.26, 2.96, 3.23 and 6.82 wt while 6.1, 6.84, 7.73 and 8.52 wt at a temperature of 77 K. To verify the simulation results, a comparison with the regression of the isothermal adosrpsi model, the comparison with the experimental results, the comparison with Density Functional Theory DFT calculations, Grand Canonical Monte Carlo GCMC simulations and MD simulation results from published reports were hold. In general comparison with semi empirical and experimental calculations, the simulation result is higher about 10 20 . With DFT and GCMC results, MD results were lower about 10 20 and with the other MD results about 5 10 . The MD results also indicate compatibility with the Langmuir isothermal model of adsorption, Sips Langmuir isothermal model and Toth Langmuir isothermal model with a coefficient of determination above 0.99 at a temperature of 298 K, above 0.95 at a temperature of 233 K and above 0.85 at a temperature of 77 K. The monolayer coverage analysis showed that without lithium doping the covered area did not exceed 30 , 40 and 55 respectively at temperatures of 298, 233 and 77 K. With lithium coverage doping rise up to 300 and achieved coverage of nearly 100 at 298, 233 and 77 K temperatures at 100, 30 and 5 atm pressure, respectively. The various thermodynamic properties showed that without modification it is to difficult for SWCNT to meet the criteria for hydrogen storage applications. The modification step made through substitution and metal doping is a roadmap that leads to the discovery of new materials that can meet the US Department of Energy US DoE targets. Thus SWBTLi2NT can be proposed as a new type of material that meets various requirements for hydrogen storage applications.

Abstrak :
In this paper, we perform combination methods of semi-empirical research, a theoretical approach, and force-matching to determine the optimum adsorption capacity on an open-ended single-walled carbon nanotube (SWCNT) as a diameter function. Using a semi-empirical study, we can determine the value of monolayer coverage and isosteric heat of adsorption from available thermodynamic data. By completing the semi-empirical study, we carried out quantum mechanical calculations to determine the adsorption energy on the interior and exterior of SWCNTs. Furthermore, monolayer coverage, specific surface area, and maximum adsorption capacity as the main quantity in the adsorption process was estimated using the combination method of force-matching and a classical Lennard-Jones potential model. Hydrogen physisorption was investigated on zig-zag SWCNTs at conditions for a pressure range of 0.1 to 10 MPa at 233 K and 298.15 K temperature. The adsorption of all data can be explained with the Toth model. The results shows the SWCNT exterior physisorption energy range between 1.35 to 1.62 kcal/mol. The interior range from 1.22 to 2.43 kcal/mol. With a wide degree of temperature and pressure variations, we obtained an optimum SWCNT diameter of 8-12 Å . At the optimum diameter maximum adsorption capacity, we achieved 1.75 wt% at 233 K and an operating pressure of 10 MPa.

Abstrak :
The effect of metal doping on the hydrogen physisorption energy of a single walled carbon nanotube (SWCNT) is investigated. Unlike many previous studies that treated metal doping as an ionic or charged element, in this study, lithium and magnesium are doped to an SWCNT as a neutral charged by substituting boron on the SWCNT (Boron substituted SWCNT). Using ab initio electronic structure calculations, the interaction potential energies between hydrogen molecules and adsorbent materials were obtained. The potential energies were then represented in an equation of potential parameters as a function of SWCNT diameters in order to obtain the most precise potential interaction model. Molecular dynamics simulations were performed on a canonical ensemble to analyze hydrogen gas adsorption on the inner and outer surfaces of the SWCNT. The isosteric heat of the physical hydrogen adsorption on the SWCNT was estimated to be 1.6 kcal/mole, decreasing to 0.2 kcal/mole in a saturated surface condition. The hydrogen physisorption energy on SWCNT can be improved by doping lithium and magnesium on Boron substituted SWCNT. Lithium-Boron substituted SWCNT system had a higher energy physisorption that was 3.576 kcal/mole compared with SWCNT 1.057–1.142 kcal/mole. Magnesium-Boron substituted SWCNT system had the highest physisorption energy that was 7.396 kcal/mole. However, since Magnesium-Boron substituted SWCNT system had a heavier adsorbent mass, its physisorption capacity at ambient temperature and a pressure of 120 atm only increased from 1.77 wt% for the undoped SWCNT to 2.812 wt%, while Lithium-Boron substituted SWCNT system reached 4.086 wt%.