scholarly journals DEKOMPOSISI AIR-METANOL MENJADI HIDROGEN PADA SEMIKONDUKTOR NATRIUM TANTALUM OKSIDA DENGAN MENGGUNAKAN LANTANUM SEBAGAI DOPING

2013 ◽  
Vol 2 (3) ◽  
pp. 12-16
Author(s):  
Husni Husin ◽  
Komala Pontas ◽  
Hesti Meilina ◽  
Fikri Hasfita
Keyword(s):  
Electron Donor ◽  
Hydrogen Generation ◽  
Pure Water ◽  
Tantalum Oxide ◽  
Methanol Decomposition ◽  
Recombination Reaction ◽  
Electron Hole ◽  
X Ray ◽  
Semiconductor Particles ◽  
Hole Recombination

Synthesis of semiconductor photocatalysts lanthanum-doped sodium tantalum oxide (La-NaTaO3) and its performance on water-methanol decomposition has been carried out. This research aimed is to examine the effect of methanol as an electron donor in the reaction to photocatalytic of hydrogen production. The samples are characterized by x-ray diffractometer (XRD) to determine its composition. The results indicate that the products are composed of NaTaO3 and Ta2O5. The reaction is conducted by irradiating of water-methanol of 400 ml and 1 g of photocatalyst in Pyrex glass reactor for 4 h at a temperature of 30 oC.The methanol solution is poured into the reactor of 5, 10, and 15 vol.%.  For comparison, in this reaction is also used only pure water. The results depict that the rate of photocatalytic hydrogen evolution from pure water as much as  0.3(mmol / g.h). Hydrogen generation rate increased significantly when the methanol are added of 5%, 10%, and 15%, ie. 2.68, 4.79 and 8.72 ,(mmol / g.h),  respectively. This has been attributed to the effect of added methanol, which acts as sacrificial electron donor and consumes photogenerated holes and/or oxygen, thereby decreasing the rates of electron-hole recombination. Reaction mechanism in semiconductor particles of NaTaO3 is also reported.

Enhanced visible-active photocatalytic behaviors observed in Mn-doped BiFeO3

2018 ◽  
Vol 32 (17) ◽  
pp. 1850185 ◽  
Author(s):  
Yun-Hui Si ◽  
Yu Xia ◽  
Ya-Yun Li ◽  
Shao-Ke Shang ◽  
Xin-Bo Xiong ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Band Gap ◽  
Diffuse Reflectance Spectroscopy ◽  
X Ray Diffraction ◽  
Electron Hole ◽  
X Ray ◽  
Mn Doped ◽  
Hole Recombination ◽  
Narrow Band Gap Semiconductors

A series of BiFeO3 and BiFe[Formula: see text]Mn[Formula: see text]O3 (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10) were synthesized by a hydrothermal method. The samples were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy (EDS) and UV–Vis diffuse reflectance spectroscopy, and their photocatalytic activity was studied by photocatalytic degradation of methylene blue in aqueous solution under visible light irradiation. The band gap of BiFeO3 was significantly decreased from 2.26 eV to 1.90 eV with the doping of Mn. Furthermore, the 6% Mn-doped BiFeO3 photocatalyst exhibited the best activity with a degradation rate of 94% after irradiation for 100 min. The enhanced photocatalytic activity with Mn doping could be attributed to the enhanced optical absorption, increment of surface reactive sites and reduction of electron–hole recombination. Our results may be conducive to design more efficient photocatalysts responsive to visible light among narrow band gap semiconductors.

CeO2/TiO2 Nanotubes Composites: Synthesis, Characterization, and Photocatalytic Properties

2012 ◽  
Vol 583 ◽  
pp. 86-90 ◽  
Author(s):  
Hai Bin Li ◽  
Xin Yong Li ◽  
Yan De Song ◽  
Shu Guang Chen ◽  
Ying Wang ◽  
...  
Keyword(s):  
Diffuse Reflectance Spectroscopy ◽  
Atomic Ratio ◽  
X Ray Diffraction ◽  
Hydrothermal Route ◽  
Electron Hole ◽  
Calcination Process ◽  
X Ray ◽  
Transmission Electron ◽  
Hole Recombination

TiO2nanotubes were prepared via a hydrothermal route. CeO2nanoparticles with diameters around 5nm were loaded onto the surface of TiO2nanotubes via a deposition approach followed by a calcination process. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-vis diffuse reflectance spectroscopy (UV-vis) were applied for the characterization of the as-prepared CeO2/TiO2nanotubes composites. The results show that CeO2particles are highly dispersed on the surface of TiO2nanotubes. The TiO2 nanotubes are modified to response to the visible light due to the combination with CeO2. The CeO2/TiO2nanotubes composites with a CeO2/TiO2atomic ratio of 2.5% show a further improvement on the photocatalytic activity for degradation of Rhodamine B in water. The presence of CeO2improves the light absorption of TiO2nanotubes and inhibits the electron-hole recombination.

Synchrotron X-Ray Topographic Studies of Recombination Activated Shockley Partial Dislocations in 4H-Silicon Carbide Epitaxial Layers

2008 ◽  
Vol 600-603 ◽  
pp. 357-360 ◽  
Author(s):  
Yi Chen ◽  
Xian Rong Huang ◽  
Ning Zhang ◽  
Michael Dudley ◽  
Joshua D. Caldwell ◽  
...  
Keyword(s):  
Stacking Faults ◽  
Epitaxial Layers ◽  
Threading Dislocations ◽  
X Rays ◽  
Electron Hole ◽  
X Ray ◽  
Shockley Partial ◽  
Partial Dislocations ◽  
Edge Component ◽  
Hole Recombination

Electron-hole recombination activated Shockley partial dislocations bounding expanding stacking faults and their interactions with threading dislocations have been studied in 4H-SiC epitaxial layers using synchrotron x-ray topography. The bounding partials appear as white stripes or narrow dark lines in back-reflection X-ray topographs recorded using the basal plane reflections. Such contrast variations are attributable to the defocusing/focusing of the diffracted X-rays due to the edge component of the partial dislocations, which creates a convex/concave distortion of the basal planes. Simulation results based on the ray-tracing principle confirm our argument. The sign of the partial dislocations can be subsequently determined.

scholarly journals Luminescence of CsI and CsI:Na Films under LED and X-ray Excitation

Coatings ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 751
Author(s):  
Jin-Cherng Hsu ◽  
Yu-Shen Ma
Keyword(s):  
Broad Band ◽  
Cesium Iodide ◽  
Exciting Light ◽  
Electron Hole ◽  
X Ray ◽  
New Energy ◽  
Section Surface ◽  
Surface Morphologies ◽  
Deposited Films ◽  
Hole Recombination

In this study, we investigated the luminous properties of undoped cesium iodide (CsI) and Na-doped CsI (CsI:Na) films deposited by thermal vacuum evaporation and treated with different substrate temperatures, post-annealing temperatures, and deposition rates. The quality of the deposited films was evaluated by their XRD pattern, SEM cross-section/surface morphologies and UV/X-ray luminescence, the spectra of which were used to derive the luminescence mechanism of the deposited films. The 310 nm luminescence demonstrates that the exciting light arises from the electron–hole recombination through the self-trapped exciton (STE) process, which is characteristic of the host polycrystalline CsI. The broad-band luminescence from ~400 to 450 nm demonstrates the other electron–hole recombination between the new energy states created by doping Na in the forbidden gap of CsI. When we deposited higher quality films at a substrate temperature of 200 °C, the undoped CsI films showed preferred crystal orientation at (200), and the CsI:Na films co-evaporated by 1 wt.% NaI at (310) and had the highest UV/X-ray luminescence.

scholarly journals Photocatalytic Hydrogen Production over Ni/La-NaTaO3 Nanoparticles from NaCl-water Solution in the Presence of Glucose as Electron Donor

2018 ◽  
Vol 17 (2) ◽  
pp. 27 ◽  
Author(s):  
Husni Husin ◽  
Komala Pontas ◽  
Yunardi Yunardi ◽  
Adi Salamun ◽  
Pocut Nurul Alam ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Hydrogen Evolution ◽  
Electron Donor ◽  
Hydrogen Generation ◽  
Water Solution ◽  
Sol Gel ◽  
H2 Production ◽  
X Ray Diffraction ◽  
X Ray ◽  
Loading Amount

Nanoparticles La-NaTaO3 photocatalyst has been synthesized via a sol-gel route. A Ninanoparticle (NPs) as a cocatalyst is loaded on La-NaTaO3 by a simple impregnation method.The products are characterized by X-ray diffraction (XRD), scanning electron microscope(SEM), a high-resolution transmission electron microscope (HRTEM) and X-ray photoelectronspectroscopy (XPS). X-ray diffraction of the La-NaTaO3 samples shows perovskite-typecrystalline orthorhombic structure. Small particulate solids of La-NaTaO3 (30-250 nm) areobserved by SEM measurement. The nickel particles are detected from HRTEM images isaround 4-8 nm. The hydrogen evolution over La-NaTaO3 with NaCl is much higher than thatwithout NaCl. The photoactivity of La-NaTaO3 is enhanced when Ni is loaded on the surfaceof La-NaTaO3. The optimum loading amount of nickel is found to be 0.3 wt.% for La-NaTaO3,and it is more effective for H2 production from NaCl-water solution in the presence glucose.It is revealed that the loaded Ni can interact with each other and cooperate on improving thephotocatalytic activity. In the case of glucose as an electron donor, the activity ofphotocatalytic hydrogen generation over Ni/La-NaTaO3 increases dramatically. NaCl andglucose can promote markedly the photocatalytic hydrogen evolution. The Ni/La-NaTaO3nanoparticles system appears to be a promising candidate, which is very important to practicalapplications, including the production of H2 from NaCl-water solution in the presence ofglucose.

Preparation of polyaniline modified BiOBr with enhanced photocatalytic activities

2017 ◽  
Vol 10 (04) ◽  
pp. 1750040 ◽  
Author(s):  
Xiaoyun Hao ◽  
Junyan Gong ◽  
Lizhen Ren ◽  
Dongen Zhang ◽  
Xin Xiao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Diffuse Reflectance ◽  
Photocatalytic Properties ◽  
X Ray Diffraction ◽  
Electron Hole ◽  
X Ray ◽  
Photocatalytic Activities ◽  
Hole Recombination ◽  
Scanning Electron

The polyaniline/bismuth oxybromide (PANI/BiOBr) hybrids materials have been synthesized hydrothermally in the presence of PANI. The PANI/BiOBr hybrids materials were confirmed by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy and ultraviolet–visible diffuse reflectance spectroscopies. Among the hybrid photocatalysts, PANI/BiOBr-0.2 showed the highest photocatalytic properties for the degradation of rhodamine B (RhB), and the increased photocatalytic properties could be due to photosensitization and the inhibited electron–hole recombination.

Hydrothermal Synthesis and Photocatalytic Hydrogen Generation of Cr3+ Doped Porous ZnIn2S4 Photocatalysts

2013 ◽  
Vol 651 ◽  
pp. 54-59 ◽  
Author(s):  
Wei Wu ◽  
Xue Feng Bai
Keyword(s):  
Crystal Structure ◽  
Photocatalytic Activity ◽  
Hydrothermal Synthesis ◽  
Hydrothermal Method ◽  
Doping Concentration ◽  
Hydrogen Generation ◽  
Electron Hole ◽  
Facile Hydrothermal Method ◽  
Photocatalytic Hydrogen Generation ◽  
Hole Recombination

A series of Cr3+doped porous ZnIn2S4photocatalysts were synthesized via a facile hydrothermal method using cetylpyridiniumbromide (CPBr) as template. The above-prepared photocatalysts were characterized by XRD, FESEM, DRS and XPS. The effects of different Cr3+doping concentration on the morphology and photocatalytic activity of ZnIn2S4photocatalysts were investigated. It is demonstrated from the experimental results that Cr3+doping in the ZnIn2S4photocatalyst had significantly influence on the crystal structure, electron-hole recombination and photocatalytic activity. The highest rate of hydrogen evolution of 3115.2 μmol/(h•g) over Cr3+(0.5%)- ZnIn2S4photocatalyst was observed.

Synthesis of Polyaniline-TiO2 Nanocomposites and Their Application in Photocatalytic Degradation

2017 ◽  
Vol 25 (7) ◽  
pp. 507-514 ◽  
Author(s):  
Nur Aziera Jumat ◽  
Phang Sook Wai ◽  
Juan Joon Ching ◽  
Wan Jefrey Basirun
Keyword(s):  
Visible Light ◽  
Chemical Structure ◽  
Reactive Black 5 ◽  
Great Efficiency ◽  
Electron Hole ◽  
X Ray ◽  
Photocatalytic Application ◽  
Template Free ◽  
Low Efficiency ◽  
Hole Recombination

Photocatalyst involving conducting polymer doped with titanium dioxide, TiO2 hold a great efficiency for photocatalytic application. In present study, polyaniline (PAni) with different TiO2 content (10%, 20%, and 40%) has been successfully synthesized through template free method. Ultraviolet-visible (UV-vis), Fourier Transform Infrared (FTIR), Raman, and X-ray Powder Diffraction (XRD) characterizations of PAni-TiO2 nanocomposites confirmed the chemical structure of polymer composites was intact after doped with TiO2. Field Emission Scanning Electron Microscope (FESEM) investigation of PAni-TiO2 nanocomposites revealed the formation of nanorod/nanotube. PAni-TiO2(10%) showed the highest conductivity 2.48 × 10−2 S/cm as compared to those with 20% and 40% of TiO2 content. Photocatalytic properties of PAni-TiO2 were examined by degrading Reactive Black 5 (RB5) dye under visible light irradiation. PAni-TiO2(10%) showed the greatest degradation (96%) than that of TiO2 (10%). Due to synergistic effect between PAni and TiO2, it is capable of absorbing visible light more efficiently and decreasing the process of electron hole recombination. Photoluminescence (PL) analysis proved low efficiency of electron hole recombination of PAni-TiO2.

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