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Development of Uv-Visible Light Active Photocatalysts for Hydrogen Production from Renewable

Thesis Info

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Author

Majeed, Imran

Supervisor

Muhammad Arif Nadeem

Program

PhD

Institute

Quaid-I-Azam University

City

Islamabad

Province

Islamabad.

Country

Pakistan

Thesis Completing Year

2017

Thesis Completion Status

Completed

Subject

Inorganic/Analytical Chemistry

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/10208/1/Imran%20Majeed_Inorganic%2c%20Analytical%20Chem_2017_QAU_PRR.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676725893320

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The development of the “hydrogen economy” requires new technologies for H2 generation, of which photocatalytic water splitting by using visible light has been viewed as most promising pathway. In present study, the photocatalysts ranging from simple metal oxides and metal sulfides to more complicated systems have been studied to achieve suitable H2 production rates from water splitting reaction The hydrogen production from water in the presence of other renewable (ethanol, glycerol, triethanolamine and ethanol water-electrolyte mixtures) were studied over three different semiconductor (TiO2, CdS and an emerging g-C3N4) supports based photocatalysts. All the synthesized catalysts were characterized by various analytical techniques such as Powder X-ray Diffraction (PXRD) for determination of crystal phase composition and purity, X-ray Photoelectron Spectroscopy (XPS) for surface elemental composition, Diffused Reflectance UV-visible Spectroscopy (DRS) for optical properties, Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy for particle size distribution and morphology, Photoluminescence (PL) for electron dynamics, Energy dispersive spectroscopy (EDS), Inductively Coupled Plasma Optical Emission spectroscopy (ICP-OES) and X-ray Fluorescence (XRF) for elemental composition, Brunauer Emmett Teller (BET) for surface area calculation and Thermogravimetric analysis (TGA) to study changes in physical and chemical properties of materials as a function of temperature. Hydrogen production for each photoreaction was measured by Gas Chromatograph (GC) equipped with molecular sieve capillary column and TCD detector. In the first section, a series of novel non-noble metal supported semiconductor photocatalysts; Cu(OH)2– Ni(OH)2/P25 (P25=80% anatase +20% rutile) and Cu(OH)2–Ni(OH)2/TNR (TNR = Titania nanorods) were prepared by co-deposition–precipitation method (total metal loading ca. 1.0 wt%) and their performance was evaluated for H2 production. Among this series, the 0.8Cu(OH)2–0.2Ni(OH)2/P25 photocatalyst showed H2 production rate of 10 and 22 mmol h‒1g‒1, in 20 vol% ethanol-water and 5 vol% glycerol-water mixtures, respectively. The 0.8Cu(OH)2–0.2Ni(OH)2/TNR photocatalyst demonstrated very high H2 production rates of 26.6 and 35.1 mmol h‒1g‒1 in 20 vol% ethanol-water and 5 vol% glycerol-water mixtures, respectively. The mechanism for high hydrogen production rate over bimetallic hydroxide supported TiO2 is investigated and established with various experimental evidences. Followed by this, a new strategy was developed to produce highly dispersed Cu and Cu2O nanoparticles over TiO2 by using MOF-199 [Cu3(BTC)2(H2O)3]n as a source of copper nanoparticles. The photocatalyst 1 wt% Cu/TiO2-400 showed a hydrogen production rate vii some 2.5 times higher than that of CuO deposited over TiO2 by conventional precipitation methods. In the second section, highly crystalline and photocatalytically active hexagonal CdS nano-support was synthesized by sol-gel method and subsequently calcination in an inert atmosphere of nitrogen. Au nanoparticles were deposited over this hexagonal CdS by a novel reductive deposition KI method involving reduction of Au3+ ions with iodide ions and used as a model to test the effect of metal particle size as well as the reaction medium on hydrogen production activity. The photocatalyst 3 wt.% Au/CdS showed the highest performance (ca. 1 molecule of H2/AuatomS−1) under visible light irradiation from water electrolyte medium (0.1M Na2S–0.02 Na2SO3; pH 13) (92%)—ethanol (8%). The validity of this new Au loading method was established by comparing it with three other conventional methods including; deposition precipitation (DP), incipient wet impregnation (WI) and photo-deposition (PD). TEM studies of fresh and used catalysts showed that Au particle size increases (almost 5 fold) with increasing photo-irradiation time due to photo-agglomeration effect and yet no sign of deactivation was observed. A mechanism for hydrogen production from ethanol waterelectrolyte mixture is presented and discussed by evaluating some intermediate formed. It is found that Au/CdS photocatalyst showing higher plasmonic effect did not necessarily produced more hydrogen in visible light range. This work also supports the electron transfer mechanism from semiconductor to metal which may further be facilitated by metal to semiconductor energy transfer mechanism due to Au surface plasmon resonance. Finally, in third section, g-C3N4 was synthesized by thermal condensation of melamine at various temperatures to get close packing and strong interlayers binding of g-C3N4. Pd and Ag bimetallic as well as monometallic nanoparticles were deposited to cope with two inherent drawbacks of g-C3N4; low visible light absorption and high recombination rate of photogenerated charge carriers. High activity of Pd-Ag/g-C3N4 photocatalyst was attributed to inherent property of palladium metal to quench photogenerated electrons by schottky barrier formation mechanism and strong silver absorption in visible range by surface plasmon resonance mechanism (SPR).
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جمیل مہدی

آہ ! جمیل مہدی
وا حسرتا! کہ دل ہے بہت بے قرار آج
سینے میں چبھ گئی ہے کوئی نوکِ خار آج
دل میں دردہے،روح مضطرب اوربے چین ہے،قلم پرلرزہ طاری ہے، زبان وبیان کی قوت دم بخود اورمردہ ہے،نبض حیات ڈوبتی ہوئی معلوم ہورہی ہے کہ میرے گذشتہ تیس(۳۰)سال کے قابل احترام بزرگ مگر بے تکلف رفیق اور ہمدم و دمساز۔ بھائی جمیل مہدی(مدیر روزنامہ’ عزائم‘ لکھنؤوماہنامہ ’برہان‘ دہلی) ۱۳/فروری۱۹۸۸ء کوصبح کوساڑھے سات بجے اس دارفانی سے داربقا کی طرف کوچ کرگئے۔اناﷲ واناالیہ راجعون۔وہ بہادر،بے خوف،جیالا بے باک وبے لوث انسان، وہ صاحب طرزادیب، وہ سراپا اخلاص و ایثار صحافی، وہ دوستوں کادوست،اپنوں کا غمخوار،چھوٹوں کامشفق وبے مربی،بزرگوں کی محفلوں میں باادب مگر بے لاگ انسان ہمیں چھوڑ گیا جس کے دم سے قلم کی آبرو سلامت تھی، اردو صحافت کی عظمت قائم تھی۔ مولانا ظفر علی خاں،مولانا ابوالکلام آزاد، غلام رسول مہرؔ،مولانا محمد علی جوہرؔ،مولانا عبدالماجد دریابادی،مولانا محمد عثمان فارقلیط کی پاکیزہ روایات کی پاسداری تھی۔اردو میں دیانت دارانہ صحافت کابھرم قائم تھا۔ آج کے خودغرضانہ ماحول،مفاد پرستیوں،ضمیرفروشیوں اورمصلحت اندیشیوں کے پُرہول سناٹے میں بھی جس کی ولولہ انگیز اور چونکا دینے والی تحریروں سے حق وصداقت کی بلند آواز گونج اٹھتی تھی،افسوس وہ آخری کڑی بھی ٹوٹ گئی جس کی بدولت ملت کے زریں عہد اورشاندار ماضی سے اس درماندہ، شکستہ اورچاروں طرف سے مہیب ومہلک خطروں سے گھرے ہوئے حال کی تاریکیاں،روشنی کی کرنیں،عمل کی توانائیاں فکروبصیرت اورتجربوں کی تجلیاں حاصل کرتی تھیں۔
آج ملک وملت کے افق پرزبردست انتشار وافتراق اورسنگین ونازک صورت حال کی ظلمتیں چھائی ہوئی ہیں،ایسے خوفناک وقت میں جبکہ طرح طرح کے طوفانوں،سیلابوں اور زلزلوں کی گڑگڑاہٹ چاروں طرف سنائی دے رہی ہے جمیل مہدی جیسے بے لاگ،بے خوف اوربے لوث اوراس قدر دیانت دارانہ اور زندہ کرداروضمیر کے حامل صحافی اورعقیدہ کے پختہ اورروشن فکر کے حامل...

NEED ANALYSIS ON ASSESSMENT BASED E-LEARNING PLATFORM IN READING CLASS FOR VOCATIONAL STUDENTS AT EAST LAMPUNG

Assessment and the learning process become two intertwined concepts that are impossible to separate. When compared to the other three abilities, reading skills are the most important in English learning. In order to meet the demands of modern teaching development, information and communication technology is required for English language instruction and assessment. The purpose of this study is to examine the requirements of both learners and pursuers in terms of the use of information and communication technology in reading instruction assessment (Reading Assessment). This current study used two data collection technique, namely questionnaires and interviews analyzed quantitatively and qualitatively. Respondents in this study were selected by purposive sampling involving 70 students and 5 teachers in vocational schools. The results of this study found that (1) The students’ goal and necessities differ, (2) The students are at beginner level at reading skill and have reading word and sentences fluently and correctly, (3) They want familiar contents based on their life, environment and major, (4) The need of information and communication technology both for learning and assessing and (5) Through the product, the English learners would be learning, collaborative and independent. The researcher advised for further researcher to conduct the development the information and communication technology for teaching and assessing English learners in vocational schools.

Exploration of Structural & Biological Aspects of Bismuth Complexes and Synthetic Application of Organogermanium Carboxylates

In a quest to discover new formulations for the treatment of various parasitic diseases, a series of triorganobismuth(v) biscarboxylates of type [R3Bi(O2CR′)2] have been synthesized, characterized and evaluated for their biological potential. The organic moiety R in the organometallics represents Ph for (1-10) and CH3-Ph for (11-22) whereas R′ represent the respective carboxylate ligands used. All the synthesized complexes were fully characterized by elemental analysis, FT-IR, multinuclear (1H, 13C) NMR spectroscopy and single crystal Xray analysis. The crystal structures for (1-6, 8, 10, 18) have been ascertained and confirmed distorted trigonal bipyramidal geometry, being monomeric with seven/five coordinated bismuth center as predicted by IR data. The synthesized complexes (1-21) when screened for antibacterial, antifungal and antileishmanial activity, demonstrated a moderate to significant potential against these microorganisms. Enzyme inhibition data for these complexes also proved to be convincing enough to signify the biological importance of these compounds. A limited Structure Activity Relationship (SAR) has been developed, demonstrating that triphenylbismuth derivatives exhibit higher biological activities in general as compared to tritolyl bismuth derivatives. Two new bismuth-oxido Carboxylate clusters (23, 24) have been synthesized including the outcome of a structurally unprecedented Bi12 Carboxylate cluster that is the first of its own kind. Both these were fully characterized by elemental analysis, FT-IR, multinuclear(1H, 13C) NMR spectroscopy and X-ray crystallography. The triphenylbismuth(III) and trifluoroacetic acid (TFAH) were reacted in toluene in the presence of Ag2O to generate the hetronuclear compound with formulation as; {[Bi4(μ3- O)2(TFA)9Ag(tol)2]2} (25) (tol = PhMe). Similarly, BiPh3, TFAH, PPh3, and Ag2O were reacted in hexane to form [Bi4(μ3-O)2(TFA)10(AgPPh3)2]n (26). Both are comprised of {Bi4(μ3-O)2} units that have been previously observed with a variety of carboxylate ligands in neutral compounds and anionic compounds. In contrast to other anionic [Bi4(μ3- O)2(TFA)N](N-8)- with metal-based counter cations, the Ag+ ions in (25) and (26) are directly attached to oxygen atoms of the TFA- ligands bonded to the bismuth core. A crystallographic evolution was observed for (25). Solvent-rich orthorhombic crystals grew initially upon standing. However, by three weeks all crystals had converted to a triclinic unit cell that contained no free solvent. Therefore molecular volume decreased from 3146.11 Å3 (orthorhombic) to 2954.06 Å3 (triclinic) resulting in formation of (25). The latter (25) possessed an intermolecular π- π stacking system between silver- and bismuth-bound toluene molecules, which explains the reorganization to a non-solvated morphology. The compound (26) crystallizes in the triclinic space group P-1 as a coordination polymer through bridging xiv carboxylates. The presence of the PPh3 ligands on Ag+ results in a higher Ag:Bi stoichiometry than for (25). The importance of the Ag2O in generating the oxido ligands was confirmed by the isolation of {[Bi2(TFA)6(TFAH)(tol)]2}n (27) from the reaction of BiPh3 with TFAH in toluene in absence of the metal oxide. A unique and previously unknown hexanitratobismuth(III) anion, [Bi(NO3)6]3− is reported for 28; [Co{HC(MeCO)2(MeCNH)}2][Bi(NO3)6]. To further explore the potential application of another main group metal, germanium, a series of substituted dihydropyrimidin-2(1H)-thione derivatives (29-36) have been synthesized using a facile and modified procedure with triphenylgermyl propionate as a catalyst. In comparison with the classical Biginelli reaction, this new protocol has the advantages of excellent yield and shorter reaction times. The synthesized compounds have been characterized by various spectroscopic techniques such as FT-IR, multinuclear (1H/13C) NMR spectroscopy and single crystal XRD analysis. Molecular docking studies were performed to identify the probable binding modes of potent inhibitors in the active site of the enzymes human topoisomerase II alpha (4FM9) and Helicobacter pylori urease (1E9Y). The compound (31) was evaluated to be the most potent inhibitor according to the molecular docking scores and molecular dynamic simulations which suggest it can be further processed as a lead molecule to interpret the pharmacological properties of such type of compounds.