scholarly journals The Effects of Grain Size, Oxidizers and Catalysts on Band Gap Energy of Gelam-Wood Carbon

2019 ◽  
Vol 2 (2) ◽  
pp. 63-70
Author(s):  
Nirwan Syarif ◽  
Dedi Rohendi ◽  
Sri Haryati ◽  
Claudia Kartika Sari Dewi ◽  
◽  
...  
Keyword(s):  
Grain Size ◽  
Metal Oxide ◽  
Band Gap ◽  
Surface Area ◽  
Band Gap Energy ◽  
Carbon Surface ◽  
Gap Energy ◽  
Wood Pyrolysis ◽  
Carboxylic Groups ◽  
Oxidized Carbon

The research of the effects of grain size, oxidizers, and catalysts on band gap energy of gelam-wood carbon has been conducted in which the carbons were produced from gelam-wood pyrolysis in high temperatures. The instrumentations used in this study were UV-Vis, FTIR spectrophotometer, and SEM. SEM and FTIR were used to characterize the morphology and the functionality of the carbon surface. UV-Vis spectrograms showed that the electronic property of carbon such as band gap was affected when grain size and surface area were changed. The increase of the functional groups in carbon occurred as the surface area of the carbon was increased. Band gap energy of crystalline carbon became much lower along with the increase in grain size due to the effects of bands-broadening. FTIR spectrograms showed that the carbon contained of hydroxyl and carboxylic groups. The hydroxyls were derived from steam-oxidized carbon that was provided narrower in the interlayer distance and lower-set band gap energy. Carboxylic groups were derived from acid nitric oxidation causing flat layer to become curved. The layers were wider and the band energy was higher. The main factor that affects the electronic structure of metal oxide in carbon/metal oxide composites was atomic alignments. The band gap energy increased along with the increase of the asymmetry alignments in metal oxide.

scholarly journals Optimized Synthesis Temperature and Time to Obtain Crystalline Carbon Nitride with Enhanced Photocatalytic Activity for Phenol Degradation

2020 ◽  
Vol 20 (6) ◽  
pp. 1392
Author(s):  
Leny Yuliati ◽  
Mohd Hayrie Mohd Hatta ◽  
Siew Ling Lee ◽  
Hendrik Oktendy Lintang
Keyword(s):  
Photocatalytic Activity ◽  
Specific Surface ◽  
Band Gap ◽  
Surface Area ◽  
Carbon Nitride ◽  
Phenol Degradation ◽  
Synthesis Temperature ◽  
Band Gap Energy ◽  
Synthesis Time ◽  
Gap Energy

In this work, the crystalline carbon nitride photocatalysts were synthesized by an ionothermal technique with varied synthesis temperature of 500, 550, and 600 °C, and synthesis time of 2, 4, and 6 h. Fourier transform infrared spectra showed the successful formation of the prepared carbon nitrides from their characteristic vibration peaks. X-ray diffraction patterns suggested that the same phase of poly(triazine imide) and heptazine could be observed, but with different crystallinity. The optical properties showed that different temperatures and synthesis time resulted in the different band gap energy (2.72–3.02 eV) as well as the specific surface area (24–73 m2 g–1). The transmission electron microscopy image revealed that the crystalline carbon nitride has a near-hexagonal prismatic crystallite size of about 50 nm. Analysis by high-performance liquid chromatography showed that the best photocatalytic activity for phenol degradation under solar light simulator was obtained on the crystalline carbon nitride prepared at the 550 °C for 4 h, which would be due to the high crystallinity, suitable low band gap energy (2.82 eV), and large specific surface area (73 m2 g–1). Controlling both the temperature and synthesis time is shown to be important to obtain the best physicochemical properties leading to high activity.

Band Gap Narrowed P Doped 1T@2H MoS2 Nanosheets Towards Synergistically Enhanced Visible Light Photochemical Property

2020 ◽  
Vol 15 (2) ◽  
pp. 257-263 ◽  
Author(s):  
Yipin Wang ◽  
Rongfang Zhang ◽  
Genliang Han ◽  
Xiaoping Gao
Keyword(s):  
Catalytic Activity ◽  
Visible Light ◽  
Band Gap ◽  
Surface Area ◽  
Hydrothermal Process ◽  
Band Gap Energy ◽  
Commercial Application ◽  
Photochemical Property ◽  
Mos2 Nanosheets ◽  
Gap Energy

The weak transport charge efficiency and great band gap energy of layered MoS2 hamper its further commercial application. To overcome these deficiencies, we report a simple, controlled and handy hydrothermal process for realizing 2H MoS2 to 1T MoS2 transition with P source. Due to the more conductive ability and larger surface area, P-doped 1T@2H MoS2 nanosheets show an outstanding catalytic activity. Noticeably, P-doped 1T@2H MoS2 nanosheets with narrowed bandgap exhibits a remarkable optical photochemical performance. It fully eliminates 50 ml of 20 mg L–1 RhB in 70 minutes with outstanding recycling and structural stability by using 10 mg catalyst.

Ultrasensitive reversible oxygen sensing by using liquid-exfoliated MoS2 nanoparticles

2016 ◽  
Vol 4 (16) ◽  
pp. 6070-6076 ◽  
Author(s):  
Yeon Hoo Kim ◽  
Kye Yeop Kim ◽  
You Rim Choi ◽  
Young-Seok Shim ◽  
Jong-Myeong Jeon ◽  
...  
Keyword(s):  
Specific Surface ◽  
Band Gap ◽  
Molybdenum Disulfide ◽  
Surface Area ◽  
Specific Surface Area ◽  
Gas Sensors ◽  
Band Gap Energy ◽  
High Specific Surface Area ◽  
Two Dimensional ◽  
Gap Energy

Two-dimensional (2D) molybdenum disulfide (MoS2) has been attracting rapidly increasing interest for application in chemoresistive gas sensors owing to its moderate band gap energy and high specific surface area.

scholarly journals Dielectric, optical and enhanced photocatalytic properties of CuCrO2 nanoparticles

RSC Advances ◽  
2017 ◽  
Vol 7 (44) ◽  
pp. 27549-27557 ◽  
Author(s):  
Tokeer Ahmad ◽  
Ruby Phul ◽  
Parvez Alam ◽  
Irfan H. Lone ◽  
Mohd. Shahazad ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Band Gap ◽  
Surface Area ◽  
Band Gap Energy ◽  
Catalytic Degradation ◽  
Photocatalytic Properties ◽  
Sunlight Irradiation ◽  
Gap Energy ◽  
Precursor Route ◽  
Citrate Precursor

Delafossite CuCrO2 nanoparticles with band gap energy of 3.09 eV and surface area of 235 m2 g−1 were prepared by citrate precursor route showed enhanced catalytic degradation of methylene blue in H2O under the sunlight irradiation.

Physico-Chemical Properties of CuO Thin Films Deposited by Spray Pyrolysis

2017 ◽  
Vol 895 ◽  
pp. 33-36 ◽  
Author(s):  
Bouzid Boudjema ◽  
Radouane Daira ◽  
Abdenour Kabir ◽  
Rafika Djebien
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Electrical Resistivity ◽  
Band Gap ◽  
Spray Pyrolysis ◽  
Copper Chloride ◽  
Band Gap Energy ◽  
Spray Pyrolysis Method ◽  
Gap Energy ◽  
Uv Visible

Our work consists to the deposition of copper oxide (CuO) thin films onto glass substrates by the spray pyrolysis method. The precursor solution was copper chloride of 0.1 M and the deposition rate was 5 ml/h. The time of spray varied between 5 and 20 min and the substrate temperature was kept at 350°C. The structural, optical and electrical properties of CuO films were investigated, as a function of the spray time, by X-ray diffraction (XRD), Raman scattering, UV-visible spectroscopy in addition to the measurements of the thickness and the electrical resistivity. The obtained results indicated that our films were polycrystalline with a preferential orientation along the (111) planes. The peaks intensity as well as the grain size increased as a function of the spray time indicating the improvement of the films crystalline structure. The Raman spectroscopy confirmed the formation of the CuO phase. The UV-visible transmission varied between 36% and 53% and the band gap energy decreased from 2 to 1.72 eV as a function of the spray time. The electrical resistivity of the films decreased from 514 to 72 kΩcm and correlated with the decrease of the band gap energy and the increase of the grain size.

scholarly journals Electroluminescence at Si band gap energy based on metal–oxide–silicon structures

2000 ◽  
Vol 87 (12) ◽  
pp. 8793-8795 ◽  
Author(s):  
Ching-Fuh Lin ◽  
C. W. Liu ◽  
Miin-Jang Chen ◽  
M. H. Lee ◽  
I. C. Lin
Keyword(s):  
Metal Oxide ◽  
Band Gap ◽  
Band Gap Energy ◽  
Gap Energy ◽  
Silicon Structures ◽  
Metal Oxide Silicon

scholarly journals Synergistic Adsorption and Photocatalytic Activity under Visible Irradiation Using Ag-ZnO/GO Nanoparticles Derived at Low Temperature

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Viet Ha Tran Thi ◽  
The Ha Cao ◽  
Tri Nhut Pham ◽  
Tien Thanh Pham ◽  
Manh Cuong Le
Keyword(s):  
Photocatalytic Activity ◽  
Low Temperature ◽  
Visible Light ◽  
Band Gap ◽  
Surface Area ◽  
Irradiation Time ◽  
Removal Rate ◽  
Band Gap Energy ◽  
Gap Energy ◽  
Visible Irradiation

Ag-ZnO/graphene oxide (AG-ZnO/GO) nanocomposite was synthesized via facile aqueous solution reactions at low temperature in order to improve the photocatalytic activity for cationic dye removal under visible light irradiation. Analytical techniques were carried out in order to determine the abilities including structure, state of elements, morphology, and surface area of synthesized materials. Ag-ZnO/GO nanocomposite presented an extremely high removal rate of methylene blue (MB) not only under UV light (over 99% removal) but also under visible light (85% removal) during the same irradiation time. In this study, initial process parameters of catalyst dosage, MB concentration, and pH of the solution were also examined for MB removal efficiency effects. The proposed mechanisms for the increased removal of MB by Ag-ZnO/GO nanocomposite under visible irradiation include increased photocatalytic degradation, mainly due to increased charge transfer capacity by lowering band gap energy; minimized recombination of the excited electron-hole pairs of ZnO with the addition of Ag into the ZnO crystal lattice; and an increased adsorption capacity with the addition of GO with high surface area and semiconductor function with zero band gap energy.

scholarly journals Influence of deposition temperature on structural, morphological, and optical properties of ZnS thin films

2018 ◽  
Vol 96 (7) ◽  
pp. 826-830
Author(s):  
Sinan Temel
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Optical Properties ◽  
Band Gap ◽  
Deposition Temperature ◽  
Band Gap Energy ◽  
Complexing Agent ◽  
Gap Energy ◽  
Nanostructured Particles ◽  
Glass Substrates

ZnS thin films were deposited onto glass substrates by chemical bath deposition (CBD) technique at different deposition temperatures (75, 80, 85, 90 °C) with non-toxic complexing agent tri-sodium citrate. Effects of deposition temperature on structural, morphological, and optical properties of thin films were investigated by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and ultraviolet–visible spectroscopy, respectively. The XRD results show that all produced ZnS thin films have cubic structure. The calculated grain size values are between 13 and 26 nm. It was observed that the grain size values increase and crystallization of films improve as the deposition temperature increases. The FESEM images reveal that film surfaces are formed by almost homogeneously dispersed nanostructured particles. Optical characterization results show that ZnS thin films have high transmittance of about 80% in the range of 400–800 nm with band gap energy values between 3.52 and 3.65 eV. As the deposition temperature increases, the band gap energy values increase. According to these results, it was observed that the structural, morphological, and optical properties of ZnS films vary depending on the deposition temperature.

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