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Home > Fabrication of Α-Hematite/Ferrite Composite Thin Films on Planar and Three-Dimensional Nanostructured Substrates for Photoelectrochemical Water Splitting

Fabrication of Α-Hematite/Ferrite Composite Thin Films on Planar and Three-Dimensional Nanostructured Substrates for Photoelectrochemical Water Splitting

Thesis Info

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Author

Hussain, Shabeeb

Program

PhD

Institute

Quaid-I-Azam University

City

Islamabad

Province

Islamabad.

Country

Pakistan

Thesis Completing Year

2018

Thesis Completion Status

Completed

Subject

Inorganic/Analytical Chemistry

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/10187/1/Shabeeb%20Hussain_Inorganic%2c%20Analytical%20Chem_2018_QAU_PRR.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676726191496

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Inspired from the natural photosynthesis in which solar radiation is being effectively utilized in photoconversion of simple compounds (H2O and CO2) into carbohydrates and oxygen, scientists are dragged toward artificial photosynthesis for obtaining important chemicals from cheap and sustainable sources. The efficient conversion of solar energy into clean form chemical energy is the concept that is considered to be effective solution of world’s growing issues i.e. increasing demand of the fossil fuels and global warming. Hydrogen is considered as the fuel of the future because it has more energy capacity than fossil fuel, yielding zero carbon emission and has competency to replace the fossil fuels being used in different sectors. Photoelectrochemical (PEC) splitting of water is considered as one of the most promising technology by which solar energy could be efficiently utilized in hydrogen generation from its cheap and abundantly available source i.e. water. In this work, we focussed on the use of α-hematite/ferrites composite thin films as electrode material for photoelectrochemical water oxidation. Based on the band gap and their band alignment knowledge, three different series of composite thin films i.e. (1) CuFe2O4/α-Fe2O3, (2) ZnFe2O4/α-Fe2O3 and (3) NiFe2O4/ α-Fe2O3 were deposited on planar and 3-dimentional (3-D) nanostructured substrates. The fabricated devices were then structurally and morphologically characterized by various techniques and evaluated for photoelectrochemical water oxidation applications. It has confirmed that the ratio between the components of the composite thin films is crucial, so the highest activity results were obtained by the thin films devices having equal molar ratio (1:1) between α-hematite and ferrites in all the three classes. Among CuFe2O4/α-Fe2O3 composite thin films series, the CF-1, having 1:1 molar ratio between CuFe2O4 and α-Fe2O3 showed the highest activity. This composite when deposited on planar FTO coated substrate showed the highest photocurrent density of 1.24 mA/cm2 at the applied voltage of 1.23 VRHE and retained the photoconversion efficiency of 0.14%. The same material when deposited on 3-D nanostructured substrate, an increase in the photocurrent density upto 2.2 mA/cm2 at the same applied voltage was recorded. Among ZnFe2O4/α-Fe2O3 composite thin films, we found that nanostructured device (ZF1-NSP) having molar ratio of 1:1 between their components retained the highest photocurrent density of 2.19 mA/cm2 and showed the photoconversion efficiency of 0.22%. This photocurrent density is 3.4 and 2.73 times higher than photocurrent density values of pure hematite on planar FTO and the highest reported value of ZnFe2O4/α-Fe2O3 composite, respectively. Among NiFe2O4/α-Fe2O3 composite thin films, the highest photocurrent density of 2.1 mA/cm2 at 1.23 VRHE was obtained for the composite device having 1:1 molar ratio of NiFe2O4/α-Fe2O3 iii deposited on 3-D nanostructured substrate (NF1-NSP), which was 3.3 times more photocurrent density than pure hematite. It has been verified by electrochemical impedance spectroscopy (EIS) that α-hematite/ferrite composite thin films have greater conductivities of charge carriers than α-hematite and the highest values of charge conductivities were obtained for the composites consisting of equal molar ratio between α-hematite and ferrite. Based on photoluminescence studies, the photogenerated charge recombination has also been decreased by increasing ferrite component in α-hematite/ferrite composite. So, the better activities of α-hematite/ferrite composite in PEC water oxidation is provided by greater electrical conductivity and reduced charged recombination as compared to pure α-hematite. The performance of 3-D nanostructured devices in photoelectrochemical water oxidation were much greater than planar devices with the similar composite thin films. The three dimensional architecture of the electrode offers large surface area for the redox reaction and larger capability to harvest visible light for enhancing the performance of 3-D nanostructured electrode as compared to planar electrode.
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انور نعمانی

انور نعمانی مرحوم
علامہ شبلیؒ نعمانی نے اپنے بھائی مولوی محمد اسحاق مرحوم وکیل الہ آباد ہائی کورٹ کی موت پر اپنے ایک پر درد نوحہ میں یہ فرمایا تھا۔
مرنے والے کو نجات ابدی کی ہو نوید
خوش و خرم رہے چھوٹایہ مرا بھائی جنید
ان ہی جناب جنید نعمانی کے مرحوم کے اکلوتے بیٹے انور نعمانی مرحوم تھے، جنھوں نے لگ بھگ اسّی۸۰ سال کی عمر میں کراچی میں مئی ۱۹۸۶؁ء کے آخری ہفتہ میں وفات پائی، مرحوم اپنے والد بزرگوار کے سایۂ عا طفت میں بڑے لاڈ پیار اور ناز ونعمت سے پلے، تعلیم مسلم یو نیو رسٹی علی گڑھ میں پائی، گھر میں دولت تھی، اس لئے ان کو نوکری کرنے کی ضرورت نہیں پڑی، کچھ دنوں مرزا پور میں فارم کیا، چھوٹی موٹی تجارت بھی کی، پھر حضرت مولانا اشرف علی تھانویؒ کے خلیفہ مولانا عبدالغنی پھولپوری کے ایسے گرویدہ اور فریضتہ ہوئے کہ وہ نقل وطن کرکے کراچی چلے گئے تو یہ بھی اپنا گھربار سب کچھ چھوڑ کر ان ہی کے ساتھ وہاں رہنے لگے، جب تک اعظم گڑھ میں رہے دارالمصنفین والوں کے یار وفادار اور غم گسار بن کر ان کے لئے اپنی محبت کا دم بھرنا زندگی کا شعار بنائے رکھا۔ کراچی میں ان کے اکلوتے لڑکے سرکاری نوکر ہیں، اچھے حال میں ہیں ،پھر ان کے اور قریبی اعزہ بھی وہاں بہت خوش حال ہیں، مگر انھوں نے کسی کے یہاں رہنا پسند نہیں کیا، اپنے مرشد کی ایک پسند یدہ مسجد سے ملحق ایک کٹیا ان ہی کے نام پر ایک عبادت گاہ کے گوشے میں رہ کر اپنی بقیہ زندگی گذاردی، کراچی جب جب گیا، ان سے جاکر ضرور ملا، اور ان کی پرانی زندگی کی یادوں کی قندیل روشن کی، کسی زمانے میں صاحب کی طرح زندگی بسر کرنے والے کو ان...

علامہ غلام رسول سعيدى كى خدمات

Allama Ghulam Rasool Saeedi is a noted contemporary Islamic scholar knows for his brilliant style of writing and ……. The way he dealt with the differing ahadith by removing the objections through providing justifying explanations in his works such as “Tibyan al Quran”, Sharah Sahih Muslim” “Tibyan Al Quraan, Sharha Saheeh Muslim, Tibyan al Furqan, Ne’am Al Bari Sharha Saheeh al Bukhari” is a great display of his skills. This article deals with conflicts found in differing ahadith quoted in “ Sharah Sahih Muslim”. In his book Ghulam Rasool saeedi has claims that there is no confilict in Ahadith but it is considered as such due to limitations of human being mind in perceive his the meanings of Ahadith. In his works he presented ample proofs to remove conflicts among the differing narrations. Some examples of his contributions in this regard include the important topics such as taking the name of Allah during ablution. He has established conformity between Quran and the Sunnah by clarifying segregation between the obligatory steps of ablution according to Quraan and the sunnah of the prophet ﷺ. Further he has conformed conflicting narrations relating to valid and invalid marriage with and/or without the permission of the guardian of the woman. He also discuss approval and disapproval of marriage in the state of wearing “Ihram” and conformity in narrations dealing with establishing purity and cleanliness of leather by tanning. Conformity in narrations stating the sacredness of Makka Muazzima and Madina Munawwara through logical reasoning.

Efficacy of Entomopathogenic Fungi and Their Combinations With Some Selective Insecticides Against Bemisia Tabaci Genn. and Tetranychus Urticae Koch on Cotton

The cotton whitefly, Bemisia tabaci Genn. and Two-Spotted Spider Mites (TSSM), Tetranychus urticae Koch are emerging as important sucking pests of cotton crop. The indiscriminate use of pesticides against insect pests have resulted in the development of resistance among these pests as well as environmental and health hazards. The use of microbial control agents is an important approach to combat this menace. The present study was therefore, carried out to determine the efficacy of some strains of entomopathogenic fungi viz., Metarhizium anisopliae, Isaria fumosorosea, Lecanicillium muscarium and Beaveria bassiana against all immature stages of whitefly and eggs and adult females of TSSM in the Department of Entomology at University of Agriculture, Faisalabad, Pakistan and Department of Pure and Applied Ecology, Swansea University, Swansea U.K. for the bioassays on whitefly. The potential of various entomopathogenic fungi was evaluated on 2 nd instar nymphs of whitefly and four of them were found promising. The detailed studies were carried out on other immature stages of whitefly with the promising strains. The dose- mortality response was observed by using serial dilutions, 1×10 5 to 1×10 8 conidia mL -1 against most susceptible stage using detached leaf immersion method for whitefly and spraying the detached leaf for bioassay with TSSM. All tested fungal isolates caused mortality in the tested stages of both insects under consideration except eggs of whitefly for which very low susceptibility was observed. The L. muscarium (V17) isolate was highly virulent among the tested ones for whitefly nymphs while Pf (n32) isolate was highly virulent against both the stages of TSSM. The mortality of each stage was recorded daily up to 8 days for both the insects under study. The % mortality significantly differed based on fungal isolates, stage of the insect and conidial concentrations. The % mortality increased with increasing the dose of conidial concentration of each fungal isolate in each insect. For whitefly, the most virulent isolate, (V17) has LC 50 value of 1.9×10 5 conidia mL -1 and it killed about 89.58 % of the treated second instar nymphs 8 days post treatment while its LT 50 value at higher concentration is 4.03 days. For TSSM, the most virulent isolate was Pf (n32) with lowest LC 50 value of 9.1 × 10 4 conidia mL -1 on 8 th day and LT 50 value of 4.58 days at 1×10 8 conidia mL -1 . It killed about 82.16 % of the inoculated females 8 days post treatment. The xresults indicated that L. muscarium and I. fumosorosea strains have potential as microbial control agent against cotton whitefly and mites, respectively, in Pakistan. The studies were also carried out to determine the LC 50 values and also efficacy of some commercial insecticides and acaricides against whitefly and TSSM in the laboratory. Four different insecticides were evaluated in the lab against 2 nd instar nymphs of whitefly on cotton. All the tested insecticides caused significant mortality of whitefly from 3-5 days post treatment. However, the most effective insecticides for whitefly, up to 5 days were Mospilon ® and Confidor ® with very low LC 50 values while others were also equally effective but with high LC 50 values. Similarly, the chlorfenapyr 36 SC, pyridaben 15 EC and fenpyroximate 5 SC proved to be the best miticides among the tested ones for the control of TSSM based on their LC 50 values. The nine commercial pesticides and their effects on germination of conidia and mycelial growth of highly efficacious fungal strains viz., I. fumosorosea and L. muscarium were investigated in vitro. There was a significant variation in conidial germination as well as mycelial growth by all tested pesticides depending upon the dose of pesticide and type of fungus. Among the pesticides tested azocyclotin was proved to be highly toxic to germination of spores as well as mycelial growth followed by pyridaben, acetamiprid and propergite while buprofezin was the least toxic. Isaria was proved to be more sensitive at field recommended doses than Lecanicillium strain to all pesticides. Generally, among all pesticides used the insecticides were more compatible to fungi than acaricides although these also inhibited germination of spores and fungal growth to some extent. The combined application of pesticides with selective fungi proved to be synergistic giving more control than used alone. The combined effects were tested under greenhouse conditions on potted plants. Buprofezin, acetamiprid, imidacloprid and diafenthuron were used against 2 nd instar nymphs of whitefly while chlorfenapyr, pyridaben and fenpyroximate were used against TSSM. Only buprofezin and imidacloprid insecticides showed synergistic effects and others additive while no one showed antagonistic results. Chlorfenapyr combined with fungus yielded highest mortality among acaricides tested. However, further investigations under field conditions may reveal more comprehensive results.