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Home > Synthesis and Characterization of Nanocrystalline Metal/Nonmetal Doped Tio 2 -Graphene Composites for Photocatalytic Applications

Synthesis and Characterization of Nanocrystalline Metal/Nonmetal Doped Tio 2 -Graphene Composites for Photocatalytic Applications

Thesis Info

Access Option

External Link

Author

Riaz, Khalid Nadeem

Program

PhD

Institute

Bahauddin Zakariya University

City

Multan

Province

KPK

Country

Pakistan

Thesis Completing Year

2001

Thesis Completion Status

Completed

Subject

Physics

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/2348/1/2936S.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727454505

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The environmental pollution on a global scale is expected to be the greatest problem that scientists will face in the 21 st century. Semiconductor photocatalysis is green technology that allows the use of sunlight for the destruction of pollutants, thus providing an attractive route to potentially solve the problem. However, the efficiency and availability of photocatalysts which can be activated by the solar spectrum and specially indoor lighting is severely limited. Therefore, the purpose of this present work was to synthesize the metal and nonmetal doped TiO 2 –graphene composite photocatalysts in order to obtain the best photocatalytic efficiency under visible light irradiation. In first step, doped TiO 2 nanoparticles were prepared by simple sol-gel method and secondly graphene-doped/TiO 2 composites were synthesized by hydrothermal process. Different characterization techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Transmission electrn microscopy (TEM), X-ray photoelectron sepectroscopy (XPS), Diffuse reflectance spetroscopy (DRS) and Photoluminscence spectroscopy (PL) were used to study the structure, morphology, chemical composition and optical properties of the prepared photocatalysts. XRD results showed that all doped and composite samples showed only anatse phase structure. It was noted that doping of TiO 2 with metals, nonmetal and also graphene incorporation did not change the anatse phase structure of TiO 2 . The average crystallite size found for all doped samples were in the range of 7-10 nm. TEM images also showed TiO 2 nanoparticles with average particle size in 8-13 nm range, which is in good agreement with XRD results. Moreover, results of all composite samples demonstrated that TiO 2 nanoparticles were successfully loaded on whole graphene sheets and hydrothermal process had played a role for the reduction of xixgraphene oxide. XPS technique confirmed that metals, nometal and graphene were present in the composite samples. Diffuse reflectance spectroscopy results demonstrated that the doping and graphene incorporation have significant effect on the optical properties of TiO 2 in visible light region. Photoluminscence results verified that metals and nometal doping and graphene introduction was effective to reduce the recombiation of photogenerated electron-hole pairs. Photocatalytic degradation of methyl orange was investigated by using different photocatalysts under visible light irradiation (λ ≥ 420 nm) for 3 h. All composite samples showed enhanced photocatalytic activty under visible light illumination. The maximum photodegradation was observed for nitrogen doped TiO 2 -graphene composite photocatalyst which is thirty time higher than commercial Degussa P25. The highest photodegradation of the composite catalyst was due to the synergetic effects of enhanced visible-light absorption, efficient charge separation, enhanced adsorptivity on the composite catalyst surface due to two-dimensional planar structure of graphene.
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91. Al-Shams/The Sun

91. Al-Shams/The Sun

I/We begin by the Blessed Name of Allah

The Immensely Merciful to all, The Infinitely Compassionate to everyone.

91:01
a. By the sunrise and its brightness,

91:02
a. and the moon as it follows it,

91:03
a. and the daylight as it displays its brightness,

91:04
a. and the nighttime as it covers it,

91:05
a. and the celestial realm and how HE built it,

91:06
a. and the earth and how HE spread it out,

91:07
a. and the soul and how HE formed it perfectly,

91:08
a. and inspired it - the soul - with its instincts of
- evil/vice - whatever will lead it away from the truth, and
- piety - whatever will keep it close to the truth.

91:09
a. Indeed, the one who purifies one’s soul of evil will succeed in the Sight of Allah,

91:10
a. and the one who corrupts one’s soul with evil will fail in the Sight of Allah.

91:11
a. The Tribe of Thamud denied and belied their Prophet Saleh
b. through their transgression.

Surah 91 * Ash-Shams 739

91:12
a. When the most wretched among them rushed forward -
b. to maim and savagely kill the she-camel.

91:13
a. And, the Messenger of Allah - Saleh - told them:
b. This is ‘the she-camel of Allah!’
c. Give her time to drink’ at the wells.

91:14
a. But they denied and belied him, and
b. maimed and savagely killed her.
c. So their...

Spontaneous Abortions and Gestational Diabetes Mellitus- A Study from Pakistan

Background: Gestational diabetes mellitus leads to adverse pregnancy outcomes. Objectives: The objective of the study was to explore the relationship of spontaneous abortions with gestational diabetes mellitus in pregnant women from rural and urban Lahore. Methods: This cross-sectional study was conducted at University of Health Sciences, Lahore in 2019. Among 60 pregnant women sampled, 30 had gestational diabetes mellitus (GDM) and 30 were normal pregnant controls. Pregnant women were sampled from different hospitals of rural and urban areas of Lahore. Independent sample t-test was applied for analyzing the data. Chi- square test was used to analyze the categorical variables. Association of fasting blood glucose (FBG) and abortions was checked. Odd ratio and relative risk were calculated. Results: Mean fasting blood sugar levels were significantly higher in GDM group (105 mg/dL) as compared to non-GDM group (80.50 mg/dL) at p<0.001. The proportions of the women with increased number of abortions had significantly higher blood glucose levels (OR 5.091, 95% CI, RR 1.27). Conclusions: Gestational diabetes mellitus is associated with an increased risk of spontaneous abortions.

Genetic Transformation and Expression Analysis of Cold Tolerant Gene in Tomato Solanum Lycopersicum Mill.

Chilling stress severely reduces the productivity of tomato as it is a cold sensitive plant. CBF3/DREB1A plays a key role in generating cold tolerance in tomato by regulating the response of multiple genes under chilling stress. In this study, cold tolerant gene (DREB1A) driven by Lip9 promoter, was transformed in three tomato genotypes (Rio Grande, Moneymaker and Roma) through Agrobacterium tumefaciens, employing tissue culture dependent and tissue culture independent transformation strategies. For tissue culture dependent transformation strategy, the effects of various PGRs (IAA, NAA, ZEA, Kin, BAP and GA3) and two ethylene inhibitors (AgNO3 and CoCl2) were investigated on callus induction and in vitro shoot regeneration. The maximum callus induction frequency (67.48%) was recorded on MS basal media enriched with 2.0 mg/l IAA, 2.5 mg/l BAP in cv. Rio Grande followed by Roma (62%) and Moneymaker (58.23%). Supplementation of AgNO3 (10-15 mg/l) in MS basal media along with PGRs (2.0 mg/l IAA, 2.5 mg/l BAP) significantly yielded the highest callus induction frequency (91.83%) in cv. Rio Grande, followed by Moneymaker (82.66%) and Roma (88.33%). Similarly, in vitro shoot regeneration frequency on MS media fortified with 0.1 mg/l IAA, 1.0 mg/l ZEA and 2.0 mg/l BAP significantly enhanced with the addition of 8-10 mg/l AgNO3 in all the cultivars i.e. in cv. Rio Grande (96.65%) followed by Roma (92.66%) and Moneymaker (90%). Likewise, the highest callogenesis (75.65%) was recorded in cv. Rio Grande on callus induction medium (CIM) supplemented with CoCl2 (5.5 mg/l), IAA (2.0 mg/l) and BAP (2.5 mg/l) followed by cv. Roma whose best callus induction (73.66%) was obtained on CIM supplemented with CoCl2 (4.5 mg/l), IAA (1.0 mg/l) and BAP (2.5 mg/l). In case of cv. Moneymaker the best callogenesis (68%) was secured on CIM having CoCl2 (3.5 mg/l), NAA (2.0 mg/l) and BAP (2.0 mg/l). The xiv highest in vitro shoot regeneration (85%, 81% and 78%) was recorded in Rio Grande, Moneymaker and Roma, respectively on shoot induction media supplemented with CoCl2 (4.25 – 5.0 mg/l). During this study, various concentrations of sucrose and sorbitol were scrutinized on in vitro shoot culture. The highest in vitro shoot regeneration frequency (100, 97.69 and 99%) was recorded in Rio Grande, Moneymaker and Roma with accumulative effect of sucrose and sorbitol (30: 30 g/l). Subsequently, transformation experiments were conducted by optimizing various factors both for tissue culture based and in planta techniques. For tissue culture based method of transformation; fifteen days old in vitro seedlings, forty-eight hours pre-culture period, bacterial density (OD600 nm = 0.2), three minutes infection period, 60 μM acetosyringone, forty-eight hours co-cultivation period, pH 5.6 of co-cultivation media, six days pre-selection duration, cefotaxime (500 mg/l) and hygromycin (35 mg/l) as lethal dose were found optimum. For in planta technique of transformation, various factors such as growing medium; soil: vermiculite (1: 1), optical density (OD600 nm = 1.0) and incubation period (20 min) were found optimum for efficient transformation efficiency. Polymerase chain reaction, Multiplex polymerase chain reaction, Southern blotting and Reverse transcriptase PCR confirmed the presence, integration and expression of DREB1A in T0 - T2 transgenic lines. Physiological and biochemical analyses of T2 transgenic plants depicted that after various chilling stresses; stomatal conductance, transpiration rate, CO2 concentration rate, photosynthetic rate, relative water contents, proline contents, total soluble sugar contents, chlorophyll contents, carotenoid contents and ascorbic acid contents of transgenic lines were significantly higher than those of NT plants. These findings clearly indicate that transgenic tomato plants over-expressing Arabidopsis CBF3 gene enhanced protection and provided cold tolerance under controlled conditions in transgenic containment.