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Suci Mufidah Winata
Abstrak :
Logam transisi decalchogenides (TMD) seperti molybdenum disulfide (MoS2) dan Tungsten disulfide (WS2) telah menarik banyak perhatian karena potensinya dalam aplikasi perangkat optoelektronik. MoS2 dan WS2 yang memiliki celah pita tunable merupakan material yang menjanjikan untuk meningkatkan rentang penyerapan cahaya pada detektor berbasis ZnO. Pada pekerjaan ini, kami melaporkan penggunaan monolayer MoS2 dan WS2 yang dideposisi pada permukaan nanorod ZnO menggunakan metode Spin-Coat untuk aplikasi fotodetektor UV-Vis. Respon fotoelektrik dari fotodetektor diamati menggunakan elektrometer di bawah penyinaran laser dioda (Thorlabs) 365, 505 dan 625 nm sebagai sumber UV dan cahaya tampak. Penggunaan metoda liquid eksfoliasi selama 8 jam dalam penelitian ini telah berhasil mensintesis nanosheet monolayer MoS2 dan WS2 yang terdiri dari 1-4 layer dengan band gap 2,23 eV dan 2,12 eV. seperti yang tercermin dari hasil TEM, spektroskopi Raman dan spektrum absorbansi larutannya. Penambahan nanosheet monolayer MoS2 dan WS2 pada ZnO nanorods terlihat tidak mempengaruhi mikrostruktur ZnO, memperlebar spektrum absorbansi dan emisi di daerah cahaya tampak. Nanokomposit ZnO/MoS2 dan ZnO/WS2 terbukti tidak sesuai untuk fotodetektor cahaya hijau (505 nm) maupun cahaya UV (365 nm) akibat peningkatan arus gelap yang menyebabkan turunnya nilai responsivitas, detektivitas dan sensitifitas. Struktur nanokomposit ZnO/WS2 dan ZnO/MoS2 menunjukkan kinerja yang lebih baik sebagai fotodetektor cahaya merah 625 nm tercermin dari kenaikan pada semua parameter responsivitas, detektivitas dan sensitifitas. ......Two dimensional layers of the transition metal decalchogenides (TMDs) such as molybdenum disulfide (MoS2) and tungsten disulfide (WS2) attract much attention due to their potential applications in optoelectronics devices. MoS2 and WS2 that has that tunable bandgap are the promising materials to enhance the light absorption range on ZnO-based photodetector. In this regard, we report the use of monolayers MoS2< and WS2 that deposited on the surface ZnO nanorods by spin-coat method for UV-Vis photodetector application. The photoelectrical response of photodetector were observed using electrometer under 365, 505, and 625 nm laser diodes (Thorlabs) as UV and visible light sources. This study show that the nanosheet monolayer MoS2 and WS2 which consists of 1-4 layers with a band gap of 2.23 eV and 2.12 eV has been succesfully sintesized by using liquid exfoliation method for 8 hours as reflected in the TEM results, Raman spectroscopy and the absorbance spectrum of the those solution. The addition of nanosheet monolayer MoS2 and WS2 in ZnO nanorods appear do not affect to ZnO microstructure, widening the absorbance and emission spectrums in visible light regions. Nanocomposite ZnO/MoS2 and ZnO/WS2 were seen to be unsuitable for green light (505 nm) and UV light (365 nm) photodetectors due to an increase in dark currents which caused a decrease in responsivity, detectivity and sentivity. The Nanocomposite ZnO/WS2 and ZnO/MoS2 shows better performance for red light (625 nm) photodetector reflected in the increase in all parameters of responsivity, detectivity and sensitivity.
Depok: Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Indonesia, 2019
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Rizantia Anggraini
Abstrak :
ABSTRAK
ABSTRACT
ZnO is one of the potential semiconductors for photodetector application. However, the responsivity and the time responses are still low and need more improvement. Therefore, the nanohybrid between ZnO and the transition metal decalchogenides (TMDs) is a promosing structure could increase the photodetector performance. In this study, ZnO nanorods structure was fabricated on the interdigitated indium tin oxide (ITO) electrode on glass substrate via ultrasonics spray pyrolysis and hydrothermal method, then MoS2 nanosheets with two different liquid exfoliation times (4 and 8 hours) were deposited on ZnO nanorods by spin-coating method. In this study it has been shown that the variation of exfoliation time of 4 and 8 hours produces MoS2 nanosheets that are almost the same number of layers, namely 3-6 layers. However, MoS2 8H can be deposited much more onto the surface of ZnO nanorods. Generally, this study shows that the addition of MoS2 can improve the performance of the ZnO nanorods photodetector in both the UV region and the visible light. Based on the increase in the value of Responsivity, Detectivity and Sensitivity, the addition of MoS2 8H produces the best nanohybrid MoS2/ZnO structure especially for red light photodetectors (625 nm) due to the highest increase in photocurrent and high electron mobility in MoS28H.
2019
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UI - Skripsi Membership  Universitas Indonesia Library
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Yohan Sutanto
Abstrak :
ZnO nanorods adalah salah satu material semikonduktor yang banyak digunakan dalam fotodetektor karena memiliki luas area aktif yang besar, serapan cahaya yang tinggi, dan mudah difabrikasi. Namun demikian, arus gelap yang tinggi menjadi masalah utamanya. Untuk itu, salah satu upaya yang dilakukan adalah dengan membuat heterostructure ZnO dengan material semikonduktor lain. Dalam penelitian ini dibuat fotodetektor zinc oxide (ZnO) dengan jua jenis MoS2 yaitu MoS2 few-layer dan MoS2 many-layer yang akan dideposisi diatas ZnO dengan metode spin coat. Pengujian fotodetektor dilakukan dibawah penyinaran sinar UV (365 nm) dan cahaya tampak (505, 625 nm) pada tegangan 2V. Hasil penelitian menunjukkan adanya peningkatan kinerja dari segi sensitivitas, responsivitas, dan detektivitas setelah penmabahan MoS2. Peningkatan kinerja ini diakibatkan oleh penurunan arus gelap yang mungkin disebabkan oleh pasivasi permukaan yang dapat menekan jumlah muatan bebas dari defect ZnO.
ZnO nanorod is a semiconductor material that is widely used in photodetector device because it has large active area, high light absorption, and  easy to manufacture. However, the high dark currents were the main problem. For that, one of the efforts made is to make the ZnO heterostructure with other semiconductor materials. In this research, zinc oxide (ZnO) photodetector was made with two types of MoS2, namely multiple-layer MoS2 and many-layer MoS2 which will be deposited on ZnO with the spin coat method. Photodetector testing was carried out under UV light (365 nm) and visible light (505, 625 nm) at a voltage of 2V. The results showed an increase in performance in terms of sensitivity, responsivity, and detectivity after the deposition of MoS2. The increase in performance is due to decrease in dark currents which may be due to surface passivation which can reduce the amount of free charge from the ZnO defect.
Depok: Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Indonesia, 2020
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Ramadhan Dwi Saputro
Abstrak :
ABSTRACT
Industri otomotif saat ini memerlukan metode peningkatan ketahanan aus yang mudah dan efisien. Lubrikasi dianggap mampu untuk menurunkan laju keausan. Dalam penelitian ini dilakukan pengaplikasian solid lubricant sebagai salah satu teknologi pada material baja SUJ 2 dengan jenis MoS2 based, grafit based, dan PTFE based sebagai metode peningkatan ketahanan aus. Pengaplikasian solid lubricant diaplikasikan dengan metode spraying untuk nantinya dapat dipelajari pengaruhnya terhadap sifat mekanik dan fisik material pada baja SUJ 2. Hasil dari pengukuran ketebalan lapisan, jenis lubrikan MoS2, grafit,dan PTFE memiliki nilai 28,2 µm, 25,1 µm, dan 59,4 µm secara berturut-turut. Pengukuran homogenitas yang dilakukan menggunakan Optical Microscope, menunjukkan homogenitas yang baik untuk lubrikan MoS2 dan grafit, sedangkan untuk PTFE homogenitasnya cenderung buruk. Nilai keausan dengan pengujian elongasi yang dilakukan selama 20 jam, didapatkan lubrikan MoS2 memberikan nilai elongasi yang paling rendah sebesar 0,162%, diikuti dengan PTFE dan grafit sebesar 0,204% dan 0,207%. Nilai kekerasan dengan pengujian mikro Vickers untuk MoS2, grafit, dan PTFE sebesar 533,5 HV, 530,5 HV, dan 530,4 HV yang cenderung mengalami penurunan jika dibandingkan tanpa penggunaan lubrikan. Kekasaran permukaan yang dihasilkan dari penambahan jenis lubrikan MoS2, grafit, dan PTFE adalah sebesar 1,67, 1,37, 3,16 yang mengalami kenaikan jika dibandingkan tanpa penggunaan lubrikan. Solid lubricant jenis MoS2 dianggap sebagai lubrikan yang paling optimum untuk digunakan pada baja SUJ 2.  
ABSTRACT
Automotive industry needs quality improvement on wear resistance properties that are easy and efficient. It is believed that lubrication is able to decreasing wear rate. In this study, the application of solid lubricant on SUJ 2 steel material with MoS2 based, graphite based and PTFE based is done as a method of increasing wear resistance. The application of solid lubricant is applied by spraying method, to later be studied the effect on the mechanical and physical properties of the material on SUJ 2 steel. The results from thickness measurement, for MoS2, graphite, and PTFE are 28.2 µm, 25.1 µm, and 59.4 µm respectively. Homogeneity measurement using Optical Microscope, shows that MoS2 and graphite have a good homogeneity, but for PTFE tend to have a poor homogeneity. The wear rate from elongation testing for 20 hours, shows that MoS2 has the lowest value 0.162%, followed by PTFE and graphite that are 0.204% and 0.207%. Hardness value from micro hardness Vickers testing for MoS2, graphite, and PTFE are 533.5 HV, 530.5 HV, and 530.4 HV that tend to be decreasing compared to original substrate without using solid lubricant. Surface roughness for MoS2, graphite, and PTFE are 1.67, 1.37, 3.16 that tend to be increasing compared to original substrate as a result from the addition of solid lubricant.
2018
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Ardina Khoirun Nisa Gunawan
Abstrak :
Indonesia merupakan Negara maritim dengan 70% wilahnya adalah perairan, namun krisis air bersih menjadi masalah utama yang belum terselesaikan. Teknologi fototermal merupakan upaya untuk memperoleh air bersih dengan material yang dapat mengkonversi cahaya matahari menjadi panas untuk menguapkan air, material yang digunakan adalah MoS2. Molibdenum disulfide (MoS2) memiliki struktur kristal berlapis dengan fasa utama 2H-MoS2 dan memiliki bentuk morfologi lembaran-lembaran yang membentuk nanoflowers dengan struktur heksagonal. Sebagai material semikonduktor, MoS2 mampu memanen cahaya pada spektrum luas dalam rentang cahaya tampak. Pada penelitian ini, MoS2 dibuat menggunakan metode hidrotermal dengan variasi durasi waktu sintesis 8, 12, dan 16 jam untuk mengamati efek efisiensi serta laju evaporasi yang optimal. Sampel MoS2-8jam menunjukkan laju evaporasi mencapai 3,31 kg/m2h dan efisiensi sebesar 104,87% yang menunjukkan bahwa mendapati hasil lebih tinggi dari dua sampel lainnya. Durasi waktu sintesis MoS2 yang singkat, dengan ukuran partikel yang kecil memiliki kemampuan penyerapan cahaya yang baik. Dimana hal ini menunjukkan bahwa MoS2 dapat meningkatkan kinerja fototermal untuk memperoleh air bersih yang efisien ......Indonesia is a maritime country, with 70% of its territory being water, but the clean water crisis is a major unresolved problem. Photothermal technology is an attempt to obtain clean water with a material that can convert sunlight into heat to evaporate water, the material used is MoS2. Molybdenum disulfide (MoS2) has a layered crystal structure with the main phase 2H-MoS2 and has a sheet morphology that forms nanoflowers with a hexagonal structure. As a semiconductor material, MoS2 can harvest light on a broad spectrum in the visible light range. In this study, MoS2 was prepared using the hydrothermal method with variations of synthesis time of 8, 12, and 16 hours to observe the effect of efficiency and optimal evaporation rate. The MoS2-8 hour sample showed an evaporation rate of 3.31 kg/m2h and an efficiency of 104.87%, which indicated that the yield was higher than the other two samples. The duration of the synthesis of MoS2 is short. With a small particle size, it has good light absorption ability, showing that MoS2 can improve photothermal performance to obtain efficient, clean water.
Depok: Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Indonesia, 2022
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Ananda Hinsa Marintan
Abstrak :
Saat ini penggunaan bahan bakar fosil sedemikian besarnya dan permintaan energi terus meningkat, namun keterbatasan bahan bakar fosil, dampak lingkungan yang dihasilkan dari pembakaan bahan bakar fosil, pengembangan teknologi penghasil energi yang bersih dan berkelanjutan menjadi sangat penting. Hidrogen adalah salah satu energi yang potensial untuk pengganti bahan bakar fosil dan merupakan energi alternatif untuk masa depan, karena ramah lingkungan dan dapat menghasilkan enenrgi yang cukup besar. Reaksi evolusi hidrogen dengan teknik elektrolisis AWE (alkaline water electrolysis) merupakan teknik yang populer saat ini untuk menghasilkan hydrogen. Penelitian ini telah berhasil mensintesis MoS2 dan komposit MoS2/Ag, serta telah dikarakterisasi dengan FTIR, XRD, FESEM, dan TEM. Fabrikasi elektroda GCE/MoS2/Ag dan uji aktivitas elektrokatalitiknya menggunakan teknik LSV, ECSA, dan CV, juga telah dilakukan. Melalui hasil pengujian Linear Sweep Voltammetry (LSV) diperoleh bahwa komposit MoS2/Ag memiliki nilai onset dan overpotensial yang paling mendekati Pt wire sebagai benchmark, yaitu 123 mV dan 253 mV. Hal ini membuktikan bahwa dekorasi MoS2 dengan Ag sudah berhasil untuk meningkatkan aktivitas katalitik dan konduktivitasnya. Melalui uji Electrochemically Active Surface Area (ECSA) diperoleh luas permukaan aktif yang paling tinggi pada nanokomposit MoS2/Ag. Berdasarkan uji kronoamperometri diketahui MoS2/Ag selama 9000 detik menghasilkan komposit yang cukup stabil sebagai elektrokatalis reaksi evolusi hidrogen. ......Currently, the use of fossil fuels is so enormous, and the demand for energy continues to increase. But the limitations of fossil fuels, the environmental impact resulting from burning fossil fuels, and the development of clean and sustainable energy-producing technologies are very important. Hydrogen is a potential energy to replace fossil fuels and is an alternative energy for the future because it is environmentally friendly and can produce quite a large amount of energy. Hydrogen evolution reaction with the AWE electrolysis technique (alkaline water electrolysis) is a popular technique today to produce hydrogen. This research has succeeded in synthesizing MoS2 and MoS2/Ag composites and have characterized by FTIR, XRD, FESEM, and TEM. GCE/MoS2/Ag electrode fabrication and electrocatalytic activity tests using LSV, ECSA, and CV techniques have also carried out. Through the LSV test results, it was found that the MoS2/Ag composite had onset and overpotential values closest to Pt wire as a benchmark, namely 123 mV and 253 mV. Prove that decorating MoS2 with Ag has succeeded in increasing its catalytic activity and conductivity. Through the Electrochemically Active Surface Area (ECSA) test, the highest active surface area was obtained on the MoS2/Ag composite. Based on the chronoamperometric test, it is known that MoS2/Ag for 9000 seconds produces a fairly stable composite as an electrocatalyst for the hydrogen evolution reaction.
Depok: Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Indonesia, 2023
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M. Hanifuddin
Abstrak :
[ABSTRAK
Tesis ini membahas pengaruh penambahan aditif pemodifikasi gesekan serbuk MoS2 ukuran 1 5 m dengan jumlah mulai 0 05 0 1 0 5 1 dan 2 berat dan ukuran 90 nm sebesar 0 05 0 1 0 5 pada minyak lumas dasar mineral HVI 60 terhadap karakteristik gesekan dan perlindungan keausannya Aditif ukuran 90 nm dan minyak lumas dasar dicampur dan diaduk menggunakan magnetik stirrer selama enam puluh menit pada suhu 50oC setelah itu dimasukkan ke dalam ultrasonic homogenizer selama satu jam sedangkan aditif ukuran 1 5 m pada suhu 75oC tanpa menggunakan ultrasonic homogenizer Campuran yang dihasilkan diuji karakteristik gesekan dan perlindungan keausannya menggunakan mesin uji four ball dan mesin uji SRV Analisis dilakukan pada material bola uji menggunakan optical emission spectroscopy OES goresan permukaan bola uji menggunakan scanning electron microscope SEM dan minyak lumas sisa pengujian dengan alat uji rotating disk electrode RDE Hasil penelitian menunjukkan bahwa penambahan aditif meningkatkan perlindungan keausan dengan dosis optimal sebesar 0 1 berat dengan rincian ukuran 1 5 m perbaikannya sebesar 23 dan ukuran 90 nm sebesar 11 Pengamatan permukaan goresan menunjukkan mekanisme keausan terjadi secara adesif dan abrasif Data yang diperoleh dari penelitian ini bisa digunakan sebagai dasar dalam pembuatan minyak lumas untuk aplikasi tertentu dengan mutu yang lebih baik
ABSTRACT
This thesis discusses the influence of MoS2 friction modifier FM addition in the form of powder with two different mesh sizes i e 90 nm and 1 5 um on the friction and wear characteristic of HVI 60 base oil The variation of MoS2 were 0 05 0 1 0 5 weight whereas MoS2 1 5 um were 0 05 0 1 0 5 1 and 2 weight MoS2 additive 90 nm was mixed with base oil and stirred with magnetic stirrer for 60 minutes at 50oC and homogenized in ultrasonic homogenizer for 1 hour For the MoS2 1 5 um the additive was mixed with base oil and stirred with magnetic stirrer for 60 minutes at 75oC without using ultrasonic homogenizer Friction and wear characteristic of these mixtures were tested using four ball and SRV test rig Ball specimen surfaces were analyzed by using optical emission spectroscopy OES the wear scars were analyzed by using scanning electron microscope SEM while used mixtures from the test were analyzed by using rotating disk electrode RDE The results of the tests showed that the addition of 0 1 weight MoS2 additive both in 90 nm and 1 5 um resulted in an optimum increase in friction and wear characteristic of 23 and 11 respectively Observation on the wear scar showed that adhesive and abrasive wear mechanism were involved in the wear process The results of this research could be applied in production of lubricating oils for certain applications to improve their quality ;This thesis discusses the influence of MoS2 friction modifier FM addition in the form of powder with two different mesh sizes i e 90 nm and 1 5 um on the friction and wear characteristic of HVI 60 base oil The variation of MoS2 were 0 05 0 1 0 5 weight whereas MoS2 1 5 um were 0 05 0 1 0 5 1 and 2 weight MoS2 additive 90 nm was mixed with base oil and stirred with magnetic stirrer for 60 minutes at 50oC and homogenized in ultrasonic homogenizer for 1 hour For the MoS2 1 5 um the additive was mixed with base oil and stirred with magnetic stirrer for 60 minutes at 75oC without using ultrasonic homogenizer Friction and wear characteristic of these mixtures were tested using four ball and SRV test rig Ball specimen surfaces were analyzed by using optical emission spectroscopy OES the wear scars were analyzed by using scanning electron microscope SEM while used mixtures from the test were analyzed by using rotating disk electrode RDE The results of the tests showed that the addition of 0 1 weight MoS2 additive both in 90 nm and 1 5 um resulted in an optimum increase in friction and wear characteristic of 23 and 11 respectively Observation on the wear scar showed that adhesive and abrasive wear mechanism were involved in the wear process The results of this research could be applied in production of lubricating oils for certain applications to improve their quality ;This thesis discusses the influence of MoS2 friction modifier FM addition in the form of powder with two different mesh sizes i e 90 nm and 1 5 um on the friction and wear characteristic of HVI 60 base oil The variation of MoS2 were 0 05 0 1 0 5 weight whereas MoS2 1 5 um were 0 05 0 1 0 5 1 and 2 weight MoS2 additive 90 nm was mixed with base oil and stirred with magnetic stirrer for 60 minutes at 50oC and homogenized in ultrasonic homogenizer for 1 hour For the MoS2 1 5 um the additive was mixed with base oil and stirred with magnetic stirrer for 60 minutes at 75oC without using ultrasonic homogenizer Friction and wear characteristic of these mixtures were tested using four ball and SRV test rig Ball specimen surfaces were analyzed by using optical emission spectroscopy OES the wear scars were analyzed by using scanning electron microscope SEM while used mixtures from the test were analyzed by using rotating disk electrode RDE The results of the tests showed that the addition of 0 1 weight MoS2 additive both in 90 nm and 1 5 um resulted in an optimum increase in friction and wear characteristic of 23 and 11 respectively Observation on the wear scar showed that adhesive and abrasive wear mechanism were involved in the wear process The results of this research could be applied in production of lubricating oils for certain applications to improve their quality ;This thesis discusses the influence of MoS2 friction modifier FM addition in the form of powder with two different mesh sizes i e 90 nm and 1 5 um on the friction and wear characteristic of HVI 60 base oil The variation of MoS2 were 0 05 0 1 0 5 weight whereas MoS2 1 5 um were 0 05 0 1 0 5 1 and 2 weight MoS2 additive 90 nm was mixed with base oil and stirred with magnetic stirrer for 60 minutes at 50oC and homogenized in ultrasonic homogenizer for 1 hour For the MoS2 1 5 um the additive was mixed with base oil and stirred with magnetic stirrer for 60 minutes at 75oC without using ultrasonic homogenizer Friction and wear characteristic of these mixtures were tested using four ball and SRV test rig Ball specimen surfaces were analyzed by using optical emission spectroscopy OES the wear scars were analyzed by using scanning electron microscope SEM while used mixtures from the test were analyzed by using rotating disk electrode RDE The results of the tests showed that the addition of 0 1 weight MoS2 additive both in 90 nm and 1 5 um resulted in an optimum increase in friction and wear characteristic of 23 and 11 respectively Observation on the wear scar showed that adhesive and abrasive wear mechanism were involved in the wear process The results of this research could be applied in production of lubricating oils for certain applications to improve their quality ;This thesis discusses the influence of MoS2 friction modifier FM addition in the form of powder with two different mesh sizes i e 90 nm and 1 5 um on the friction and wear characteristic of HVI 60 base oil The variation of MoS2 were 0 05 0 1 0 5 weight whereas MoS2 1 5 um were 0 05 0 1 0 5 1 and 2 weight MoS2 additive 90 nm was mixed with base oil and stirred with magnetic stirrer for 60 minutes at 50oC and homogenized in ultrasonic homogenizer for 1 hour For the MoS2 1 5 um the additive was mixed with base oil and stirred with magnetic stirrer for 60 minutes at 75oC without using ultrasonic homogenizer Friction and wear characteristic of these mixtures were tested using four ball and SRV test rig Ball specimen surfaces were analyzed by using optical emission spectroscopy OES the wear scars were analyzed by using scanning electron microscope SEM while used mixtures from the test were analyzed by using rotating disk electrode RDE The results of the tests showed that the addition of 0 1 weight MoS2 additive both in 90 nm and 1 5 um resulted in an optimum increase in friction and wear characteristic of 23 and 11 respectively Observation on the wear scar showed that adhesive and abrasive wear mechanism were involved in the wear process The results of this research could be applied in production of lubricating oils for certain applications to improve their quality , This thesis discusses the influence of MoS2 friction modifier FM addition in the form of powder with two different mesh sizes i e 90 nm and 1 5 um on the friction and wear characteristic of HVI 60 base oil The variation of MoS2 were 0 05 0 1 0 5 weight whereas MoS2 1 5 um were 0 05 0 1 0 5 1 and 2 weight MoS2 additive 90 nm was mixed with base oil and stirred with magnetic stirrer for 60 minutes at 50oC and homogenized in ultrasonic homogenizer for 1 hour For the MoS2 1 5 um the additive was mixed with base oil and stirred with magnetic stirrer for 60 minutes at 75oC without using ultrasonic homogenizer Friction and wear characteristic of these mixtures were tested using four ball and SRV test rig Ball specimen surfaces were analyzed by using optical emission spectroscopy OES the wear scars were analyzed by using scanning electron microscope SEM while used mixtures from the test were analyzed by using rotating disk electrode RDE The results of the tests showed that the addition of 0 1 weight MoS2 additive both in 90 nm and 1 5 um resulted in an optimum increase in friction and wear characteristic of 23 and 11 respectively Observation on the wear scar showed that adhesive and abrasive wear mechanism were involved in the wear process The results of this research could be applied in production of lubricating oils for certain applications to improve their quality ]
2015
T43066
UI - Tesis Membership  Universitas Indonesia Library
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Ahmad Syahroni
Abstrak :
Molybdenum disulfide (MoS2), yang merupakan bagian dari kelompok material yang disebut dengan transition metal dichalcogenides, menarik banyak perhatian dikarenakan sifat-sifat fisis yang unik yang dimilikinya. Single layer material ini mengalami transisi indirect band gap ke direct band gap, yang karenanya dapat dimanfaatkan untuk berbagai aplikasi optoelektronik. Untuk mempelajari struktur pita (band structure) dari material ini secara detail. pendekatan first-principles seperti density functional theory (DFT) menjadi pilihan populer. Namun, terdapat tantangan yang besar untuk menggunakan pendekatan tersebut untuk menghitung dengan benar efek yang ditimbulkan akibat korelasi kuat antar elektron. Saat ini, telah diperkenalkan sebuah pendekatan yang menggabungkan DFT dengan apa yang disebut dengan GW+BSE untuk menghitung efek interaksi elektron-elektron dan elektron-hole. Dalam tesis ini, kami mempelajari sifat-sifat optik 1H- dan distorted 1T'-MoS2 dengan mengikutsertakan dalam perhitungan interaksi antar elektron dalam kerangka GW dan elektron-hole dengan menyelesaikan persamaan Bethe-Salpeter (BSE). ......Molybdenum disulfide (MoS2), which belongs to transition metal dichalcogenides, has attracted great attention mainly due to their unique physical properties. A single layer of this material undergoes indirect to direct band gap transition, which enables a wide range of optoelectronic applications. To explore the details of the band structure of this material. a first-principles approach such as density functional theory (DFT) has become a popular choice. However, apart from its well-established formulation, it remains a big challenge to use such an approach to capture effects arising from correlations among the electrons correctly. Nowadays, an approach to combine DFT with a so-called GW+BSE to address the effects of electron-electron and electron-hole interactions, has been introduced. In this thesis, we study the optical properties of 1H- and distorted 1T-MoS2 taking into account electron-electron interaction within GW approximation and electron-hole interaction by solving Bethe-Salpeter equation (BSE).
Depok: Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Indonesia, 2019
T53298
UI - Tesis Membership  Universitas Indonesia Library
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Mona Dini Mardia
Abstrak :
Seng Oksida (ZnO) adalah fotokatalis semikonduktor yang menjanjikan karena harganya yang ekonomis, ramah lingkungan, tidak mudah bereaksi kimia serta stabil. Namun laju rekombinasi muatan yang tinggi membuat aktifitas fotokatalitiknya kurang optimal. Salah satu cara untuk mengurangi rekombinasi muatannya adalah dengan menggabungkan ZnO dengan semikonduktor lain yang memiliki energi band gap lebih rendah, antara lain bahan Transition Metal Di-Chalcogenides (TMDC). Pada penelitian ini, ZnO nanorods (NRs) disintesis dengan metode Ultrasonic Spray Pyrolysis (USP) dan metode hidrotermal diatas substrat kaca kemudian dilanjutkan dengan deposisi MoS2 dan WS2 diatas ZnO nanorod dengan metode spincoating. Untuk mendapatkan nanosheets MoS2 dan WS2, dilakukan eksfoliasi dengan metode Liquid Phase Exfoliation (LPE). Selanjutnya dilakukan karakterisasi morfologi, struktur dan sifat optik menggunakan SEM,TEM,XRD, XPS, Raman spectroscopy, UV-Vis and Photoluminescence Spectroscopy untuk menganalisis pengaruh penambahan MoS2 dan WS2 terhadap aktivitas fotokatalitik ZnO NRs. Kemudian  hibrida ZnO/Mo2 dan ZnO/WS2 digunakan sebagai fotokatalis untuk mendegradasi metil biru dibawah penyinaran cahaya tampak dan sinar UV. Hasil menunjukkan bahwa deposisi MoS2 dan WS2 pada ZnO NRs memperlambat laju degradasi metil biru akibat sifat hidrofobik MoS2 dan WS2 yang menghalangi adsorpsi molekul H2O. Persen degradasi MB oleh fotokatalis ZnO murni, ZnO/MoS2 dan ZnO/WS2 selama 37,5 menit dibawah penyinaran cahaya tampak secara berturut-turut adalah 87,7%, 85,2%, dan 83,6% sedangkan dengan penyinaran ultraviolet adalah 81,0%, 78,2%, dan 77,9%. Degradasi metil biru oleh fotokatalis ZnO/WS2 lebih lambat daripada ZnO/MoS2 disebabkan ZnO/WS2 bersifat lebih hidrofobik seperti terlihat dari sudut kontak air terhadap permukaannya yang lebih tinggi. ......Zinc oxide (ZnO) is a promising semiconductor photocatalyst due to its low cost, enviromentally friendly and chemical innertness and photostability. However, the high rate of charges recombination makes its photocatalytic activity is less optimal. One way to reduce the charges recombination rate is by decorating the ZnO with other semiconductors that have lower bandgap, such as transition metal dichalcogenides (TMDCs). In this study, ZnO nanorods were synthesized via ustrasonic spray pyrolysis and hydrothermal method on the the glass substrate and then followed by deposition of molybdenum disulfide (MoS2) and tungsten disulfide (WS2) on ZnO nanorods by using spincoating method. In order to produce MoS2 and WS2 nanosheets, this materials was firstly exfoliated by liquid phase exfoliation method. The morphology, structural and optical properties characterization by using SEM, TEM, XRD, XPS, Raman spectroscopy, UV-Vis and Photoluminescence Spectroscopy was performed to analyze the influence of MoS2 and WS2 on the photocatalytic activity ZnO NRs. Then the hybrid ZnO/MoS2 and ZnO/WS2 were used as photocatalyst for degradation of methyl blue under visible and UV light. Percentage degradation of MB by pure ZnO, ZnO/MoS2 and ZnO/WS2 photocatalysts for 37.5 minutes under visible light irradiation were 87.7%, 85.2%, and 83.6% respectively while those with ultraviolet radiation were 81,0%, 78.2%, and 77.9%. The degradation of methyl blue by ZnO/WS2 photocatalyst is slower than ZnO/Mo2 because Zn /WS2 is more hydrophobic as seen from the higher contact angle to the water.
Depok: Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Indonesia, 2019
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Ferina Livya Kirana
Abstrak :
Sistem evaporasi fototermal telah menjadi solusi yang menjanjikan dalam mengatasi krisis air bersih dalam beberapa tahun terakhir. Sistem ini menggunakan energi matahari untuk menguapkan air yang tercemar atau air laut, meninggalkan zat-zat berbahaya atau garam dan menghasilkan air bersih yang dapat digunakan kembali. Molibdenum disulfida (MoS2) merupakan salah satu material fototermal yang menarik karena memiliki karakteristik penyerapan sinar yang luas pada daerah cahaya tampak. Hal ini memungkinkan MoS2 untuk mengkonversikan sinar matahari menjadi panas dengan efisiensi yang tinggi. Penting untuk mempelajari morfologi, struktur mikro, dan sifat optik dari MoS2. Annealing adalah proses perlakuan panas yang dilakukan pada material untuk mengubah struktur kristal dan sifat-sifatnya. Dengan mengontrol parameter annealing seperti suhu dan waktu, kita dapat mengubah morfologi partikel MoS2 menjadi bentuk yang diinginkan. Perubahan ini dapat berdampak pada penyerapan sinar matahari dan efisiensi konversi energi fototermal. Disini, kami menganalisis pengaruh perlakuan annealing terhadap morfologi, mikro struktur MoS2. Hasil pengujian kinerja evaporasi fototermal menunjukkan bahwa sampel MoS2-400 memiliki laju evaporasi tertinggi, yaitu sebesar 1,65 kg/m2h. Berdasarkan hasil ini, dapat disimpulkan bahwa perlakuan annealing dapat berpengaruh dan meningkatkan kinerja laju evaporasi fototermal. ......Photothermal evaporation systems have emerged as a promising solution to overcome the clean water crisis in recent years. This system utilizes solar energy to evaporate polluted air or seawater, leaving behind harmful substances or salts and producing clean water that can be reused. Molybdenum disulfide (MoS2) is an interesting photothermal material due to its wide absorption characteristic in the visible light region, allowing it to efficiently convert sunlight into heat. Therefore, it is essential to study the morphology, microstructure, and optical properties of MoS2. Annealing is a heat treatment process performed on a material to alter its crystal structure and properties. By controlling the annealing parameters such as temperature and time, we can change the morphology of the MoS2 particles to the desired shape. These changes can significantly impact the absorption of sunlight and the efficiency of photothermal energy conversion. In this study, we analyze the effect of the annealing treatment on the morphology and microstructure of MoS2. The results of the photothermal evaporation performance test revealed that the MoS2-400 sample exhibited the highest evaporation rate, reaching 1.65 kg/m2 h. Based on these findings, we can infer that the annealing settings can influence and enhance the performance of the photothermal evaporation rate.
Depok: Fakultas Matematika Dan Ilmu Pengetahuan Alam Universitas Indonesia, 2023
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