Second Generation Visible-Light-Active Photocatalysts: Preparation, Optical Properties, and Consequences of Dopants on the Band Gap Energy of TiO2

Nanocomposite (NCP) films of polycarbonate-polybutylene terephthalate (PC-PBT) blend as a host material to Cr2O3 and CdS nanoparticles (NPs) were fabricated by both thermolysis and casting techniques. Samples from the PC-PBT/Cr2O3 and PC-PBT/CdS NCPs were irradiated using different doses (20–110 kGy) of γ radiation. The induced modifications in the optical properties of the γ irradiated NCPs have been studied as a function of γ dose using UV Vis spectroscopy and CIE color difference method. Optical dielectric loss and Tauc's model were used to estimate the optical band gaps of the NCP films and to identify the types of electronic transition. The value of optical band gap energy of PC-PBT/Cr2O3 NCP was reduced from 3.23 to 3.06 upon γ irradiation up to 110 kGy, while it decreased from 4.26 to 4.14 eV for PC-PBT/CdS NCP, indicating the growth of disordered phase in both NCPs. This was accompanied by a rise in the refractive index for both the PC-PBT/Cr2O3 and PC-PBT/CdS NCP films, leading to an enhancement in their isotropic nature. The Cr2O3 NPs were found to be more effective in changing the band gap energy and refractive index due to the presence of excess oxygen atoms that help with the oxygen atoms of the carbonyl group in increasing the chance of covalent bonds formation between the NPs and the PC-PBT blend. Moreover, the color intensity, ΔE has been computed; results show that both the two synthesized NCPs have a response to color alteration by γ irradiation, but the PC-PBT/Cr2O3 has a more response since the values of ΔE achieved a significant color difference >5 which is an acceptable match in commercial reproduction on printing presses. According to the resulting enhancement in the optical characteristics of the developed NCPs, they can be a suitable candidate as activate materials in optoelectronic devices, or shielding sheets for solar cells.

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Band-gap-energy-adjustable and noble-metal-free modified NiS-Zn Cd1-S for highly efficient visible-light-driven Cr6+ photoreduction in alkaline wastewater

Journal of Physics and Chemistry of Solids ◽

10.1016/j.jpcs.2020.109893 ◽

2021 ◽

Vol 150 ◽

pp. 109893

Author(s):

Linjuan Wang ◽

Ling Zan

Keyword(s):

Visible Light ◽

Band Gap ◽

Noble Metal ◽

Band Gap Energy ◽

Gap Energy ◽

Metal Free ◽

Highly Efficient ◽

Visible Light Driven

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Structural, Spectroscopic and Optical Properties of Monohydrated Adenine: A Theoretical Study

Dhaka University Journal of Science ◽

10.3329/dujs.v64i2.54491 ◽

2016 ◽

Vol 64 (2) ◽

pp. 157-161

Author(s):

M Alauddin ◽

MM Islam ◽

MA Aziz

Keyword(s):

Optical Properties ◽

Band Gap ◽

Theoretical Study ◽

Minimum Energy ◽

Band Gap Energy ◽

Gap Energy ◽

B3lyp Level ◽

A Minor ◽

Homo Lumo ◽

Hydrogen Bonded

The structural, spectroscopic (IR, NMR and UV-Vis), electronic and optical properties of monohydrated adenine (monohydrated 6-aminopurine, C5H5N5.H2O) are investigated theoretically using DFT/B3LYP level of theory. Three minimum energy structures have been identified for monohydrated of adenine where H2O molecule is doubly hydrogen bonded with adenine.1H NMR analysis shows that the protons which are hydrogen bonded become deshielded and chemical shift moves to the higher frequency region.Five IR active mode of vibrations were found at 3108, 3295, 3665, 3676 and 3719 cm-1 which are assigned as bonded -OH vibration of H2O, Bonded -NH vibration of NH2, Free -NH vibration of adenine (9 N), Free -NH vibration of NH2, Free -OH vibration of H2O, respectively and agree well with the available experimental results. The investigation of electronic properties shows that the HOMO-LUMO band gap energy of monohydrated adenine at B3LYP level is 5.15 eV. The major electronic transition (from HOMO to LUMO (83%) (π→π*)) occurs at 258 nm (4.80 eV) with a minor transition at 237 nm (5.23 eV). Theoretically it is observed that the HOMO-LUMO band gap energy is for monohydrated adenine is lower than that of adenine. Dhaka Univ. J. Sci. 64(2): 157-161, 2016 (July)

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Development of the Morphology and the Band Gap Energy of Co–Si Nanofibers by Inserting Zirconium and Titanium with Dual Anions Intercalation Process

Applied Sciences ◽

10.3390/app9224775 ◽

2019 ◽

Vol 9 (22) ◽

pp. 4775 ◽

Cited By ~ 2

Author(s):

Osama Saber ◽

Nagih M. Shaalan ◽

Aya Osama ◽

Adil Alshoaibi

Keyword(s):

Optical Properties ◽

Band Gap ◽

Optical Materials ◽

Band Gap Energy ◽

Gap Energy ◽

Intercalation Process ◽

Trivalent Cations ◽

Optical Applications ◽

Double Hydroxides ◽

First Time

The plate-like structure is the most familiar morphology for conventional layered double hydroxides (LDHs) in case their structures consist of divalent and trivalent cations in their layers. In this study, nanofibers and nanoneedles of Co–Si LDHs were prepared for the first time. By the inclusion of zirconium inside the nanolayers of LDH structures, their plates were formed and transformed to nanofibers. These nanofibers were modified by the insertion of titanium to build again plate-like morphology for the LDH structure. This morphology controlling was studied and explained by a dual anions intercalation process. The optical properties of Co–Si LDHs indicated that the incorporation of zirconium within their nanolayers decreased the band gap energy from 4.4 eV to 2.9 eV. Following the same behavior, the insertion of titanium besides zirconium within the nanolayers of Co–Si LDHs caused a further reduction in the band gap energy, which became 2.85 eV. Although there is no data for the optical properties of Co–Si LDHs in the literature, it is interesting to observe the low band gap energy for Co–Si LDHs to become more suitable for optical applications. These results concluded that the reduction of the band gap energy and the formation of nanofibers introduce new optical materials for developing and designing optical nanodevices.

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Effect of ZnO on a Superhydrophilic Self-Cleaning Properties of TiO2/SiO2 Thin Film on Glass Slide Substrate

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1131.237 ◽

2015 ◽

Vol 1131 ◽

pp. 237-241 ◽

Cited By ~ 1

Author(s):

Akkarat Wongkaew ◽

Chanida Soontornkallapaki ◽

Naritsara Amhae ◽

Wichet Lamai

Keyword(s):

Thin Film ◽

Contact Angle ◽

Visible Light ◽

Band Gap ◽

Sol Gel ◽

Dip Coating ◽

Band Gap Energy ◽

Gap Energy ◽

Coating Method ◽

Dip Coating Method

This work aims to study the effect of ZnO containing in TiO2/SiO2 film on the superhydrophilic property after exposed to different types of light. The metal solutions were prepared by sol-gel technique and the film was deposited on glass slides by dip coating method. The parameter studied was the amount of ZnO in the TiO2/SiO2 film. The contents of ZnO were 5-20% weight (increased by 5%). The amount of TiO2 was constant at 30% weight. The obtained films were analyzed for their roughness. The results indicated that film roughness changed according to the ZnO contents. With 5%ZnO in the thin film, the roughness was 0.726 nm while 20%ZnO obtained the roughness of 2.128 nm. UV-Vis spectrophotometer was used for measuring of transmittance of films. At wavelength of 550 nm, the transmittances of each film were greater than 90%. Band gap energy of each film was calculated from the transmittance data. It was found that the average band gap energy of the films was 2.47 eV. Then, the films contained various amount of ZnO were grouped into 2 sets. The first set was exposed to visible light while the other set was exposed to UV. The duration of exposure was 5 hr. Both sets of films after exposed to any light were kept in a black box controlled relative humidity of 85%. Each film was measured contact angle every day. It was found that the 30%TiO2/5%Zn/SiO2 film exposed to visible light showed the best superhydrophilic property. The contact angle was about 0-5° within 3 days. This may due to the reduction of band gap energy in the presence of ZnO in TiO2/SiO2 films to 2.41 eV and the roughness of the film.

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Dressing of Mwcnts with TiO2 Nanoparticles Using Modified Microwave Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.364.228 ◽

2011 ◽

Vol 364 ◽

pp. 228-231 ◽

Cited By ~ 7

Author(s):

Mohammad Hafizuddin Haji Jumali ◽

K. Mohamad Al Asfoor Firas ◽

Shahidan Radiman ◽

Akrajas Ali Umar

Keyword(s):

Optical Properties ◽

Band Gap ◽

Absorption Spectra ◽

Band Gap Energy ◽

Microwave Method ◽

Gap Energy ◽

Vis Spectroscopy ◽

Significant Change ◽

Strong Attachment ◽

Absorption Wavelength

Optical properties of TiO2 dressed on the surface of MWCNTs have been investigated. The samples were prepared using modified microwave method and characterized using TEM, XRD and UV-Vis spectroscopy. A clear interface between MWCNT and TiO2 indicated strong attachment between these two nanostructures. Significant change in absorption spectra proved the absorption wavelength and band gap energy of TiO2 nanostructures can be controlled via dressing of MWCNT.

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Increasing Rutile Phase Amount in Chromium-Doped Titania by Simple Stirring Approach for Photodegradation of Methylene Blue under Visible Light

Australian Journal of Chemistry ◽

10.1071/ch14565 ◽

2015 ◽

Vol 68 (7) ◽

pp. 1129 ◽

Cited By ~ 6

Author(s):

Pei Wen Koh ◽

Leny Yuliati ◽

Hendrik O. Lintang ◽

Siew Ling Lee

Keyword(s):

Methylene Blue ◽

Visible Light ◽

Band Gap ◽

Rutile Phase ◽

Band Gap Energy ◽

Synthesis Process ◽

Doped Tio2 ◽

Gap Energy ◽

Stirring Time ◽

Doped Titania

The amount of rutile phase in chromium-doped titania photocatalyst was controlled by varying stirring time (0.5–2.0 h) at room temperature during a sol–gel synthesis process. The percentage of rutile phase increased from 15.1 % to 28.6 % when stirring time was prolonged from 0.5 to 1.5 h. Further increases in the stirring time had negligible effect on the rutile phase amount. As evidenced by analyses using diffuse reflectance ultraviolet–visible spectroscopy and X-ray photoelectron spectroscopy, a sufficient stirring time was important for more substitution of Cr3+ for Ti4+ in the lattice, resulting in anatase-to-rutile phase transformation. The formation of more rutile phase in Cr-doped TiO2 not only reduced the band gap energy, but also induced surface defects that retarded electron–hole recombination. It has been demonstrated that the Cr-doped TiO2 prepared with a stirring time of 1.5 h possessed the lowest band gap energy of 1.89 eV, and hence it achieved the highest photodegradation of methylene blue under visible light irradiation.

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Effect of Doping Concentration on the Optical Properties of Indium-Doped Gallium Arsenide Thin FILMS

Journal of Bangladesh Academy of Sciences ◽

10.3329/jbas.v40i2.30773 ◽

2016 ◽

Vol 40 (2) ◽

pp. 179-186 ◽

Cited By ~ 1

Author(s):

Md Saiful Islam ◽

Chitra Das ◽

Mehnaz Sharmin ◽

Kazi Md Amzad Hussain ◽

Shamima Choudhury

Keyword(s):

Thin Films ◽

Optical Properties ◽

Band Gap ◽

Doping Concentration ◽

High Vacuum ◽

Band Gap Energy ◽

Crystal Thickness ◽

Thermal Evaporation Method ◽

Gap Energy ◽

Indium Doping

Effects of indium doping (concentration 0.2, 0.3 and 0.4%) on the optical properties of GaAs thin films were studied. Thin films of 600 nm were grown onto chemically and ultrasonically cleaned glass substrate by thermal evaporation method in high vacuum (~10-4 Pa) at 50°C fixed substrate temperature. The samples were annealed for 15 minutes at a fixed temperature of 200°C. The thicknesses of films were being measured in situ by a quartz crystal thickness monitor during deposition. The transmittance and reflectance data were found using UV-VIS-NIR spectrophotometer in the photon wavelength range of 310 ~ 2500 nm. These data were utilized to compute the absorption coefficient, refractive index, extinction co-efficient and band gap energy of the studied films. Here transmittance was found 78 for 0.2% indium doping concentration. The band gap energy decreased with the increase of doping concentration.Journal of Bangladesh Academy of Sciences, Vol. 40, No. 2, 179-186, 2016

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N-Loaded TiO2 for Photocatalytic Degradation of Methyl Orange under Visible Light Irradiation

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.622-623.883 ◽

2012 ◽

Vol 622-623 ◽

pp. 883-888

Author(s):

Natkritta Boonprakob ◽

Natda Wetchakun ◽

Sukon Phanichphant ◽

Jun Chen ◽

Burapat Inceesungvorn

Keyword(s):

Methyl Orange ◽

Visible Light ◽

Band Gap ◽

Visible Light Irradiation ◽

Sol Gel ◽

Band Gap Energy ◽

Light Irradiation ◽

Gap Energy ◽

Visible Light Driven ◽

Degradation Of Methyl Orange

Nitrogen-loaded TiO2(N-loaded TiO2), a visible-light driven catalyst, was successfully synthesized by the modified sol-gel method. Physical characterizations of the as-prepared catalysts have been performed by using X-ray diffraction (XRD), Diffuse reflectance UVvisspectroscopy(DRUVvis), Raman spectroscopyand BETspecific surface areain order to obtain structure-activity relationship. Results from Raman spectroscopy clearly suggested that N atoms were incorporated into the TiO2crystal lattice as evidenced by the vibrational peak of TiN in TiO2-xNx.DR UVvis results also suggested that the nitrogen dopant might be responsible for narrowing the TiO2band gap energy, thus resulting in a shift towards the visiblelight region. Photocatalytic activity of N-loaded TiO2evaluated through the degradation of methyl orange (MO)under visible light irradiation (l> 400 nm) indicated that all N-loaded photocatalysts exhibited significantly higher activities than the unloaded TiO2and Degussa P25 TiO2. According to the results from DR UV-vis, XRD and BET studies, the enhanced photoactivity observed from N-loaded samples might be due to a decrease in TiO2band gap energy and/or changes in chemical and physical properties of the materials upon loading with nitrogen.

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