The effects of cotton cellulose on both energy band gap of g-C3N4–TiO2 nanoparticles and enhanced photocatalytic properties of cotton-g-C3N4–TiO2 composites

In this paper, we report a new, simple method for the synthesis of CdS and ZnS nanoparticles (NPs) prepared in a basic aqueous medium using metal xanthate as the sulfur source. The structure, morphology, size distribution, optical band gap, and photocatalytic properties of the newly obtained nanomaterials were investigated by UV-Vis spectroscopy, X-ray diffraction, and transmission electron microscopy. The results show that both CdS and ZnS crystallized in cubic phase and formed NPs with average sizes of 7.0 and 4.2 nm for CdS and ZnS, respectively. A blue shift of UV-Vis absorbance band and higher energy band gap values were observed for both materials in comparison with their bulk counterparts, which is in accordance with the quantum confinement effect. The as-prepared nanomaterials were tested in visible-light driven photocatalytic decomposition of methylene blue (MB). After irradiation for 180 min, the degradation rate of MB with a concentration of 8 × 10−6 mol/L mixed with a photocatalyst (CdS or ZnS, both 10 mg in 100 mL solution of MB) was found to be 72% and 61%, respectively. The CdS NPs showed better photocatalytic activity than ZnS, which could be explained by their lower energy band gap and thus the ability to absorb light more efficiently when activated by visible-light irradiation.

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STUDY OF TiO2 NANOPARTICLES’ STRUCTURE USING DENSITY FUNCTIONAL THEORY BASED TIGHT BINDING METHOD

Scientific Journal of Tra Vinh University ◽

10.35382/18594816.1.27.2017.132 ◽

2019 ◽

Vol 1 (27) ◽

pp. 79-85

Author(s):

Hung Thanh Phan

Keyword(s):

Density Functional Theory ◽

Band Gap ◽

Tio2 Nanoparticles ◽

Energy Band ◽

Density Functional ◽

Anatase Phase ◽

Tight Binding ◽

Energy Band Gap ◽

Functional Theory ◽

Practical Applications

The different structure and size of TiO2 nanoparticles ranging from 0.8 nm to 2.7 nm with two different phases of anatase and rutile were studied by Density Functional theory based Tight Binding (DFTB) method. The results showed that the stability of the rutile phase was better than that of the anatase phase. Based on calculation of the electronic properties of particles, the energy band gap of rutile particles was comparable to that of bulk structure. In contrast, the energy band gap of the anatase changed irregularly. Moreover, the formation energy that was used for forming the particles was inversely proportional to their size based on computation of energy. The results provided useful instructions for practical applications in fabrication of TiO2 nanoparticles.

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Synthesis of Oxygen Deficient TiO2 for Improved Photocatalytic Efficiency in Solar Radiation

Catalysts ◽

10.3390/catal11080904 ◽

2021 ◽

Vol 11 (8) ◽

pp. 904

Author(s):

Kassim Olasunkanmi Badmus ◽

Francois Wewers ◽

Mohammed Al-Abri ◽

Mohd Shahbaaz ◽

Leslie F. Petrik

Keyword(s):

Solar Radiation ◽

Visible Light ◽

Band Gap ◽

Tio2 Nanoparticles ◽

Energy Band ◽

High Energy ◽

Orange Ii ◽

Tio2 Photocatalyst ◽

Energy Band Gap ◽

Visible Light Active

The photocatalytic activities of TiO2 have been limited mainly to absorbing in the ultraviolet spectrum which accounts for only 5% of solar radiation. High energy band gap and electron recombination in TiO2 nanoparticles are responsible for its limitations as a photocatalyst. An oxygen deficient surface can be artificially created on the titanium oxide by zero valent nano iron through the donation of its excess electrons. A visible light active TiO2 nanoparticle was synthesized in the current investigation through simple chemical reduction using sodium boro-hydride. The physical and textural properties of the synthesized oxygen deficient TiO2 photocatalyst was measured using scanning/ transmission electron microscopy while FTIR, XRD and nitrogen sorption methods (BET) were employed for its further characterizations. Photochemical decoloration of orange II sodium dye solution in the presence of the synthesized TiO2 was measured using an UV spectrophotometer. The resulting oxygen deficient TiO2 has a lower energy band-gap, smaller pore sizes, and enhanced photo-catalytic properties. The decoloration (88%) of orange (II) sodium salt solution (pH 2) under simulated solar light was possible at 20 min. This study highlights the effect of surface oxygen defects, crystal size and energy band-gap on the photo-catalytical property of TiO2 nanoparticles as impacted by nano zero valent iron. It opens a new window in the exploitation of instability in the dopant ions for creation of a visible light active TiO2 photocatalyst.

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No Resistive Normal Electrons in Beginning Superconducting States

Mathematics ◽

10.3390/math8091512 ◽

2020 ◽

Vol 8 (9) ◽

pp. 1512

Author(s):

Changho Seo ◽

Seongsoo Cho ◽

Je Huan Koo

Keyword(s):

Band Gap ◽

Energy Band ◽

Energy Band Gap

We investigate why normal electrons in superconductors have no resistance. Under the same conditions, the band gap is reduced to zero as well, but normal electrons at superconducting states are condensed into this virtual energy band gap.

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Insights into the structural, electronic and optical properties of MgA2B4(A = Sc, Y; B = S, Se) spinel compounds: Direct energy band gap materials

Materials Science in Semiconductor Processing ◽

10.1016/j.mssp.2021.105736 ◽

2021 ◽

Vol 127 ◽

pp. 105736

Author(s):

Muhammad Saeed ◽

Zubaida Noor ◽

Amel Laref ◽

Hind Althib ◽

Tahani H. Flemban ◽

...

Keyword(s):

Optical Properties ◽

Band Gap ◽

Energy Band ◽

Energy Band Gap ◽

Electronic And Optical Properties ◽

Spinel Compounds ◽

Direct Energy

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Energy Band Gap Studies of CdS Nanomaterials

Journal of Nano Research ◽

10.4028/www.scientific.net/jnanor.3.97 ◽

2008 ◽

Vol 3 ◽

pp. 97-102 ◽

Cited By ~ 17

Author(s):

Dinu Patidar ◽

K.S. Rathore ◽

N.S. Saxena ◽

Kananbala Sharma ◽

T.P. Sharma

Keyword(s):

Optical Absorption ◽

Band Gap ◽

Energy Band ◽

Chemical Method ◽

Optical Absorption Spectroscopy ◽

Cds Nanoparticles ◽

X Ray Diffraction ◽

Energy Band Gap ◽

X Ray ◽

Simple Chemical

The CdS nanoparticles of different sizes are synthesized by a simple chemical method. Here, CdS nanoparticles are grown through the reaction of solution of different concentration of CdCl2 with H2S. X-ray diffraction pattern confirms nano nature of CdS and has been used to determine the size of particle. Optical absorption spectroscopy is used to measure the energy band gap of these nanomaterials by using Tauc relation. Energy band gap ranging between 3.12 eV to 2.47 eV have been obtained for the samples containing the nanoparticles in the range of 2.3 to 6.0 nm size. A correlation between the band gap and size of the nanoparticles is also established.

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