scholarly journals Semiconductor nanostructures for device applications

2015 ◽  
Author(s):  
Μοχάμεντ Άμπακερ-Ανταμ
Keyword(s):  
Methylene Blue ◽  
Rhodamine B ◽  
Semiconductor Nanostructures ◽  
Device Applications ◽  
P Type

Στην παρούσα διατριβή παρουσιάζεται η σύνθεση ημιαγώγιμων νανοδομών και η εφαρμογή τους σε διατάξεις. Μέρος 1 Παρουσιάζεται η σύνθεση επιταξιακών εξαγωνικών δίσκων οξειδίου του Χαλκού CuO μέσω μίας υδροθερμικής διαδικασίας ανάπτυξης χαμηλής θερμοκρασίας. Η μορφολογική μελέτης καθώς και ο δομικός χαρακτηρισμός έχουν γίνει με τις μεθόδους FESEM, TEM, HRTEM και XRD αντίστοιχα. Οι οπτικές ιδιότητες μελετήθηκαν μέσω UV/VIS φασματοσκοπίας σε θερμοκρασία δωματίου, όπου υπολογίστηκαν τα έμμεσα και άμεσα χάσματα τα οποία είναι ελαφρώς μετατοπισμένα προς το μπλε σε σχέση με τις τιμές του μακροσκοπικού υλικού. Επίσης η καθαρότητα και η σύσταση των δειγμάτων μελετήθηκαν μέσω EDS και FTIR. Τέλος, έχει προταθεί ένας μηχανισμός ανάπτυξης για τον σχηματισμό των επιταξιακών εξαγωνικών δίσκων οξειδίων του χαλκού. Μέρος 2 Αναφέρεται στην παρασκευή υψηλής ευαισθησίας χημικών αισθητήρων 4-nitrophenol (4-NP) που βασίζονται στους νανοκύβους του CuO. Ο δομικός χαρακτηρισμός επιβεβαίωσε την νανοκρυσταλλική φύση και μονοκλινή δομή των δειγμάτων. Οι οπτικές ιδιότητες των νανοκύβων μελετήθηκαν με UV-Vis φασματοσκοπία σε θερμοκρασία δωματίου, και παρουσίασαν έμμεσο και άμεσο χάσμα. Οι νανοκύβοι CuO χρησιμοποιήθηκαν για την παρασκευή χημικών αισθητήρων 4-nitrophenol (4-NP) μέσω μίας απλής I-V τεχνικής. Οι αισθητήρες αυτοί παρουσίασαν υψηλή ευαισθησία ~132.84 ± 0.02 mA.cm-2.(mol L-1)-1 και όριο ανίχευσης ~5×10-9 mol L-1 σε μικρό χρόνο απόκρισης ~10.0 s. Μέρος 3 Παρουσιάζεται υψηλής απόδοσης σύνθεση, λεπτομερής χαρακτηρισμός και η εφαρμογή στη φωτοκατάλυση νανοσωματιδίων α-Fe2O3. Το φάσμα απορρόφησης UV-Vis παρουσίασε δύο οπτικά χάσματα που αντιστοιχούν σε άμεσες και έμμεσες μεταβάσεις αντίστοιχα. Τα νανοσωματίδια α-Fe2O3 εμφανίζουν καλές φωτοκαταλυτικές ιδιότητες στη καταλυτική υποβάθμιση του methylene blue. Μέρος 4 Παρουσιάζεται η σύνθεση νανοελλειψοειδών α-Fe2O3 μέσω μίας υδροθερμικής μεθόδου χαμηλής θερμοκρασίας και η χρήση τους για την παρασκευή χημικών αισθητήρων αμμωνίας υψηλής απόδοσης, με την I-V τεχνική. Οι λεπτομερείς δομικές και οπτικές ιδιότητες επιβεβαίωσαν την ρομβοεδρική δομή και τα άμεσα και έμμεσα ενεργειακά χάσματα αντίστοιχα. Οι αισθητήρες αυτοί παρουσίασαν υψηλή ευαισθησία ~4.678 µA.cm-2.mM-1 και όριο ανίχευσης ~0.04 nM με συντελεστή συσχέτισης (R) 0.995 σε μικρούς χρόνους απόκρισης (10.0 sec). Μέρος 5 Παρουσιάζεται η ευρείας κλίμακας σύνθεση νανονιφάδων SnS2 καθώς επίσης και ο χαρακτηρισμός τους. Οι φωτοκαταλυτικές ιδιότητες των νανονιφάδων SnS2 παρουσίασαν υποβάθμιση 61% της Rhodamine B υπό ακτινοβολία ορατού φωτός. Επιπλέον οι SnS2 νανονιφάδες χρησιμοποιήθηκαν για την παρασκευή χημικών αισθητήρων νιτροανιλίνης μέσω της I-V τεχνικής. Οι αισθητήρες παρουσίασαν υψηλή ευαισθησία ~ (505.82 ± 0.02) mA.cm-2.(mole/L)-1 και πειραματικό όριο ανίχνευσης ~15*10-6 (mole/L) σε μικρό χρόνο απόκρισης ~10.0 sec.Μέρος 6, Παρασκευάστηκε διάταξη ετεροδομής με νανοφύλλα SnS(p-type)/TiO2 νανοσωματίδια (n-type) επάνω σε γυαλί FTΟ με λεπτή επιφανειακή επίστρωση Pt δημιουργώντας μία διάταξη διόδου Pt/SnS/TiO2/FTO. Η ετεροδομή αυτή εμφάνισε βελτιωμένες ηλεκτρικές ιδιότητες με υψηλό ρεύμα 0.78 mA στο 1V, παράγοντα ιδεατότητας 31 και σχετικά υψηλό φράγμα δυναμικού 0.634 eV.Λέξεις κλειδιά: Ημιαγώγιμες νανοδομές, Οξείδιο του χαλκού, Οξείδιο του σιδήρου, Σουλφίδια του κασσιτέρου, Υδροθερμική διαδικασία, Οπτικό ενεργιακό χάσμα, Χημικοί αισθητήρες, Φωτοκαταλυτική υποβάθμιση, Δίοδος ετεροεπαφής.

Synergistic and Competitive Adsorption of Methylene Blue and Rhodamine B on Core-shell Magnetic Manganese Dioxide Nanocomposites

2017 ◽  
Vol 13 (6) ◽  
Author(s):  
Linshan Wang ◽  
Cholhwan Kim ◽  
Xinyue Zhang ◽  
Carlos Fernandez ◽  
Ting Sun ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Manganese Dioxide ◽  
Rhodamine B ◽  
Competitive Adsorption ◽  
Core Shell

A 3D 2-fold interpenetrating Cu(II) coordination polymer based on 4,4′-oxybis(benzoic acid) and 1,3-bis(2-methyl-imidazol-1-yl) benzene exhibiting photocatalytic properties

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Shan-Bao Qiao
Keyword(s):  
Methylene Blue ◽  
Coordination Polymer ◽  
Benzoic Acid ◽  
Rhodamine B ◽  
Photocatalytic Properties

Abstract A new Cu(II) complex, [Cu2(1,3-BMIB)(OBA)2] n (1) (1,3-BMIB = 1,3-bis(2-methyl-1H-imidazol-1-yl)benzene, H2OBA = 4,4′-oxybis(benzoic acid)) was hydrothermally synthesized and has been structurally characterized. Complex 1 possesses a 3D 2-fold interpenetrating framework based on [Cu(OBA)] n layers with a Schläfli symbol {412.63}. Complex 1 displays excellent photocatalytic properties in the degradation of methylene blue (MB) and rhodamine B (RhB).

Shape Effect of Zinc-Tin Oxide Nanostructures on Photodegradation of Methylene Blue and Rhodamine B under UV and Visible Light

2021 ◽  
Vol 4 (2) ◽  
pp. 1149-1161 ◽  
Author(s):  
Ana Rovisco ◽  
Rita Branquinho ◽  
Jonas Deuermeier ◽  
Tomás Freire ◽  
Elvira Fortunato ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Visible Light ◽  
Tin Oxide ◽  
Rhodamine B ◽  
Shape Effect ◽  
Oxide Nanostructures ◽  
Zinc Tin Oxide

SiC Epitaxial Layers Grown by Sublimation Method and their Electrical Properties

2007 ◽  
Vol 556-557 ◽  
pp. 153-156
Author(s):  
Chi Kwon Park ◽  
Gi Sub Lee ◽  
Ju Young Lee ◽  
Myung Ok Kyun ◽  
Won Jae Lee ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Epitaxial Layer ◽  
Light Emission ◽  
Epitaxial Layers ◽  
Current Voltage ◽  
Space Technique ◽  
Sublimation Method ◽  
Device Applications ◽  
P Type ◽  
Surface Morphologies

A sublimation epitaxial method, referred to as the Closed Space Technique (CST) was adopted to produce thick SiC epitaxial layers for power device applications. In this study, we aimed to systematically investigate surface morphologies and electrical properties of SiC epitaxial layers grown with varying a SiC/Al ratio in a SiC source powder during the sublimation growth using the CST method. It was confirmed that the acceptor concentration of epitaxial layer was continuously decreased with increasing the SiC/Al ratio. The blue light emission was successfully observed on a PN diode structure fabricated with the p-type SiC epitaxial layer. Furthermore, 4H-SiC MESFETs having a micron-gate length were fabricated using a lithography process and their current-voltage performances were characterized.

Facile Synthesis of Boron Organic Polymers for Efficient Removal and Separation of Methylene Blue, Rhodamine B, and Rhodamine 6G

2018 ◽  
Vol 6 (12) ◽  
pp. 16777-16787 ◽  
Author(s):  
Xue Zhao ◽  
Dan Wang ◽  
Changjun Xiang ◽  
Fulin Zhang ◽  
Luchang Liu ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Rhodamine B ◽  
Rhodamine 6G ◽  
Organic Polymers ◽  
Efficient Removal ◽  
Facile Synthesis

scholarly journals B-Cyclodextrin Polyurethanes Copolymerised with Beetroot Fibers (Bio-Polymer), for the Removal of Organic and Inorganic Contaminants from Water

2013 ◽  
Vol 2 (1) ◽  
pp. 150 ◽  
Author(s):  
Jamil Rima ◽  
Karine Assaker
Keyword(s):  
Heavy Metals ◽  
Methylene Blue ◽  
Polycyclic Aromatic Hydrocarbons ◽  
Water Treatment ◽  
Aromatic Hydrocarbons ◽  
Rhodamine B ◽  
Industrial Wastewater ◽  
Contaminated Groundwater ◽  
Inorganic Contaminants ◽  
Polycyclic Aromatic

<p>In this study, B-Cyclodextrinn polymerized with beetroot fibers (Bio-polymer), was prepared and applied to the removal of organic and inorganic contaminants from wastewater. An investigation into the use of cross-linked cyclodextrin polyurethanes copolymerised with beetroot fibers as adsorbents for organic pollutants and heavy metals has yielded very useful results which may have an impact in future water treatment applications.</p> The Biopolymer was tested in water contaminated by dyes, polycyclic aromatic hydrocarbons (PAH) and heavy metals. The effectiveness to eliminate dyes such as methylene blue and Rhodamine B with concentrations around 100 ppm was more than 99%, while the pyrene,which was chosen as an example among PAHs, showed a potential of elimination exceeding the 97% for solutions of 10 ppm. Also, heavy metals, such as Lead, Zn, and Cu, were tested and showed an efficacy exceeding the 99.8%. The results indicated that the biopolymer developed in this study has the potential to be a promising material for the removal of mixed pollutants from industrial wastewater or from contaminated groundwater.

scholarly journals Studies on Synthesis, Characterization, and Adsorption of Cationic Dyes from Aqueous Solutions Using Magnetic Composite Material from Natural Clay in Central Kalimantan, Indonesia

Molekul ◽  
2018 ◽  
Vol 13 (1) ◽  
pp. 63
Author(s):  
I Made Sadiana ◽  
Karelius Karelius ◽  
Retno Agnestisia ◽  
Abdul Hadjranul Fatah
Keyword(s):  
Magnetic Material ◽  
Aqueous Solution ◽  
Methylene Blue ◽  
Composite Material ◽  
Rhodamine B ◽  
Solid Phase ◽  
Magnetic Composite ◽  
Natural Clay ◽  
Central Kalimantan ◽  
Adsorption Capacities

Clay is a natural material from crystalline silicate with layered structures, has high cation exchange capacity, and large surface area. These advantages can be used as an adsorbent for the removal of contaminants in aqueous solutions, such as heavy metals and dyes. In Indonesia, clays from Java, Sulawesi, and Sumatra islands have been used as adsorbent, furniture, and construction materials. Due to limited information about basic characteristics of clay from Kalimantan, this clay has not been utilized well. Therefore, natural clay from Kalimantan, especially in Central Kalimantan, was used as adsorbent of cationic dyes in this present study. However, the clay has difficulty for separating the solid phase from aqueous solution after adsorption process. To solve this problem, combining clay with magnetic material was opted. The objectives of this study are to synthesize the magnetic composite material from natural clay by coprecipitation method and to characterize the synthesized magnetic composite material using an x-ray diffraction method, transmission electron microscopy, and vibrating sample magnetometer. The adsorption properties of the synthesized magnetic composite material were evaluated using rhodamine B and methylene blue dyes in aqueous solution. Before magnetic composite material was synthesized, the clay was previously being activated for removing impurities. The magnetic material formed in the structure of clay had magnetite with particle size of 2.75 nm and the magnetization value of 24.91emu/g. The adsorption capacities of natural clay, activated clay, and magnetic composite of clay in rhodamine B were 34.29, 76.27, and 81.46 mg/g, respectively, while in methylene blue were 30.25, 83.92, and 133.90 mg/g, respectively. These results suggested that magnetic composite of clay can increase the adsorption capacities against dyes and accelerate the separation of the adsorbent solid phase from aqueous solution with largest adsorption capacity on methylene blue dye.

Photovoltaic Characterization of Trapping in Porous Silicon

1994 ◽  
Vol 358 ◽  
Author(s):  
D. W. Boeringer ◽  
R. Tsu
Keyword(s):  
Porous Silicon ◽  
Photovoltaic Effect ◽  
Light Spot ◽  
Dangling Bond ◽  
Photogenerated Electrons ◽  
Device Applications ◽  
Photovoltaic Characterization ◽  
P Type ◽  
Silicon Based ◽  
Position Sensitive Detectors

ABSTRACTWe report the first observation of the lateral photovoltaic effect in porous silicon. Contacts placed on either side of a porous silicon region develop a voltage up to several millivolts if the sample is asymmetrically illuminated. If the light spot is closer to one contact, the voltage will have one polarity; if it is closer to the other contact, the polarity will be opposite. In the case of n-type, the contact nearest the light spot is positive; for p-type, the contact nearest the light spot is negative In the region between the contacts, the photovoltage varies almost linearly with the position of the light spot, over a distance 4.5 cm across. The origin of our lateral photoeffect may be explained by the trapping of photoexcited carriers by a pair of dangling bond centers in porous silicon. In the case of p-type, the photogenerated electrons are trapped by the dangling bond states while holes diffuse away in the substrate. The situation for n-type is opposite; holes are trapped by the dangling bond states while electrons diffuse away in the substrate. This differs from the conventional lateral photoeffect, which arises under the nonuniform illumination of a junction between two layers of differing conductivities. Hamamatsu sells silicon-based position-sensitive detectors with a resolution down to 0.1 µm. The possibility of using this lateral photoeffect to characterize these dangling bond states in porous silicon as well as several possible device applications will be discussed.

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