scholarly journals Characterization, Photoelectric Properties, Electrochemical Performances and Photocatalytic Activity of the Fe2O3/TiO2 Heteronanostructure

2021 ◽  
Author(s):  
Salah Kouass ◽  
Hassouna Dhaouadi ◽  
Abdelhak Othmani ◽  
Fathi Touati
Keyword(s):  
Photocatalytic Activity ◽  
Energy Gap ◽  
Specific Capacity ◽  
Charge Carriers ◽  
Electrochemical Performances ◽  
Photogenerated Electrons ◽  
Electron Hole Pair ◽  
Photocatalytic Reactions ◽  
Photoluminescence Studies ◽  
Redox Ability

The Fe2O3/TiO2 nanocomposite was synthesized on FTO subtract via hydrothermal method. The crystal structure, morphology, band structure of the heterojunction, behaviors of charge carriers and the redox ability were characterized by XRD, HR-TEM, absorption spectra, PL, cyclic voltammetry and transient photocurrent spectra. The as-prepared Fe2O3/TiO2 photocatalysts with distinctive structure and great stability was characterized and investigated for the degradation of methylene blue (MB) dye in aqueous solution. The ability of the photocatalyst for generating reactive oxygen species, including O2− and.OH was investigated. It was revealed that the combination of the two oxides (Fe2O3 and TiO2) nano-heterojunction could enhance the visible response and separate photogenerated charge carriers effectively. Therefore, the remarkable photocatalytic activity of Fe2O3/TiO2 nanostructures for MB degradation was ascribed to the enhanced visible light absorption and efficient interfacial transfer of photogenerated electrons from to Fe2O3 to TiO2 due to the lower energy gap level of Fe2O3/TiO2 hybrid heterojunctions as evidenced by the UV–Vis and photoluminescence studies. The decrease of the energy gap level of Fe2O3/TiO2 resulted in the inhibition of electron–hole pair recombination for effective spatial charge separation, thus enhancing the photocatalytic reactions. Based on the obtained results, a possible mechanism for the improved photocatalytic performance associated with Fe2O3/TiO2 was proposed. The Fe2O3/TiO2 nanocomposite has a specific capacity of 82 F.g−1 and shows a higher capacitance than Fe2O3.

scholarly journals Pt Nanowire-Anchored Dodecahedral Ag3PO4{110} Constructed for Significant Enhancement of Photocatalytic Activity and Anti-Photocorrosion Properties: Spatial Separation of Charge Carriers and PhotogeneratedElectron Utilization

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 206
Author(s):  
Hanxu Zhu ◽  
Yekun Ji ◽  
Lifang Chen ◽  
Weilin Bian ◽  
Jinnan Wang
Keyword(s):  
Photocatalytic Activity ◽  
Electronic Conductivity ◽  
Active Species ◽  
The Body ◽  
Charge Carriers ◽  
Cubic Phase ◽  
Long Distance ◽  
Photogenerated Electrons ◽  
O2 Reduction ◽  
Pt Nanowires

Pt nanowire-anchored dodecahedral Ag3PO4{110} was constructed for organics photodegradation. SEM and TEM images confirmed that the Pt nanowires were grafted on dodecahedral Ag3PO4, which was entirely bounded by {110} facets. All the X-ray diffraction peaks of the samples were indexed to the body-centered cubic phase of Ag3PO4, indicating that Pt nanowire-anchored dodecahedral Ag3PO4 well maintained the original crystal structure. The rhombic dodecahedral Ag3PO4 entirely bounded by {110} facets achieved high photocatalytic activity. Due to the formation of a Schottky barrier, the Pt nanowires improved the separation of the charge carriers of Ag3PO4. Furthermore, they provided a fast expressway to transfer the photogenerated electrons and prolonged the lifetime of the charge carriers via long-distance transport, resulting in the accumulation of holes on Ag3PO4 for organics degradation. More importantly, the Pt nanowires improved the reduction potential of the photogenerated electrons for O2 reduction to ·O2−, which enhanced the photocatalytic activity and anti-photocorrosion properties of Ag3PO4. We found that 99.5% of Rhodamine B (RhB) could be removed over 0.5ωt% Pt nanowire-anchored dodecahedral Ag3PO4 within 10 min. Even after 10 cycles, the photocatalytic activity was still high. photoluminescence (PL), time-resolved photoluminescence (TRPL), UV–vis diffuse reflectance spectra (UV–visDRS), and photoelectrochemical analysis showed that Pt nanowire-anchored dodecahedral Ag3PO4 exhibited lower bandgap, higher photocurrent intensity, better electronic conductivity, and longer charge carriers lifetime than other types of Ag3PO4 crystals. Radical trapping experiments and electron paramagnetic resonance (EPR) analysis demonstrated that the holes were the main active species for organics photodegradation.

scholarly journals Recent Advances in Doped Bi2O3 and its Photocatalytic Activity: A Review

2022 ◽  
Vol 9 (1) ◽  
pp. 216-230
Author(s):  
Bella Aprimanti Utami ◽  
Heri Sutanto ◽  
Eko Hidayanto
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Visible Light Irradiation ◽  
Energy Gap ◽  
Light Irradiation ◽  
High Electron ◽  
Photocatalytic Ability ◽  
As Doping ◽  
Electron Hole Pair ◽  
Defect Recognition

Bismuth Oxide (Bi2O3) has a very promising photocatalytic ability to degrade waste pollutants under visible light irradiation because it has a small energy gap of around 2.85-2.58 eV. Although it has excellent potential as a photocatalyst, Bi2O3 has the disadvantage of a high electron-hole pair recombination rate, which will reduce its photocatalytic activity. To overcome these problems, surface modifications, defect recognition, or doping of Bi2O3 are carried out to obtain a more effective and efficient photocatalyst to degrade waste pollutants under visible light irradiation. Several studies by researchers have been described for the modification of Bi2O3 by doping. Various types of doping are given, such as doping in elements or doping in the form of compounds to form composites. Based on several studies that have been described, appropriate doping has been shown to increase the photocatalytic activity of Bi2O3. Keywords: Bi2O3, Photocatalyst, Doping

scholarly journals Electrostatic Asymmetry of Single-Crystal Nanostructures and Their Photocatalytic Properties

2020 ◽  
Author(s):  
Ming Zhou ◽  
Ji-Young Kim ◽  
Myung Geun Han ◽  
Xiaotao Zu ◽  
Kai Sun ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Charge Separation ◽  
High Energy ◽  
Charge Carriers ◽  
Planar Geometry ◽  
Electron Holography ◽  
Surface Areas ◽  
Energy Technologies ◽  
Zinc Cadmium ◽  
Photocatalytic Reactions

Abstract Efficient light absorption and high energy of charge carriers of zinc cadmium sulfide (ZCS) make this semiconductor attractive for many photocatalytic reactions. Despite marked successes in shape-controlled synthesis of ZCS central to their photocatalytic performance, recombination of charge carriers as they migrate through the nanoscale particles result in losses of excitation energy markedly reducing photocatalytic activity of ZCS and other heterogeneous photocatalysts. Here we show that electrostatic asymmetry of single-crystalline ZCS with planar geometry assists charge separation and substantially increase the yield of photocatalytic reactions. The synthesized ZCS nanorods and nanoplates with identical chemical composition were found to have markedly different photocatalytic activity for evolution of hydrogen in water. Despite much smaller specific surface areas, the ~ 500 nm wide nanoplates displayed hydrogen evolution rate 12 times higher than the ~ 35 nm long nanorods also outperforming other ZCS photocatalysts. Experimental and computational data indicate that the homo and heterojunction-free ZCS nanoplates with continuous wurtzite lattice behave essentially as nanoscale dipoles. Electric-field-directed migration of charge carriers stimulates their localization on opposite parts of the nanoplates. Direct imaging of intraparticle electrical field using off-axis electron holography confirmed their electrostatic asymmetry. Polarization-enhanced charge separation provides a new pathway to efficient and stable photocatalysts for sustainable energy technologies.

Impact of Al doping on a hydrothermally synthesized β-Ga2O3 nanostructure for photocatalysis applications

RSC Advances ◽  
2021 ◽  
Vol 11 (13) ◽  
pp. 7338-7346
Author(s):  
Sunjae Kim ◽  
Heejoong Ryou ◽  
In Gyu Lee ◽  
Myunghun Shin ◽  
Byung Jin Cho ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Grain Boundary ◽  
Redox Potential ◽  
Surface Area ◽  
Crystal Defect ◽  
Oxygen Defect ◽  
Al Doping ◽  
Photocatalytic Reactions

The photocatalytic activity is correlated with different parameters affecting the photocatalytic reactions; redox potential (RP), surface area (SA), crystal defect (CD), oxygen defect (OD), and grain-boundary induced defect (GD).

On the mechanism of photocatalytic reactions on CuxO@TiO2 core-shell photocatalyst

2021 ◽  
Author(s):  
Kunlei Wang ◽  
Zuzanna Bielan ◽  
M. Ando ◽  
Marcin Janczarek ◽  
Dong Zhang ◽  
...  
Keyword(s):  
Charge Carriers ◽  
Environmental Applications ◽  
Core Shell ◽  
Highly Active ◽  
Photocatalytic Reactions

Titania (titanium(IV) oxide) is highly active, stable, cheap and abundant photocatalyst, and thus commonly applied in various environmental applications. However, two main shortcomings of titania, i.e., charge carriers’ recombination and...

CdSe/CdS Quantum Dot Core-Shell for Silicon Solar Cell Efficiency Enhancement

2020 ◽  
Vol 29 ◽  
pp. 8-14
Author(s):  
Manal Midhat Abdullah ◽  
Omar Adnan Ibrahim
Keyword(s):  
Solar Cell ◽  
Silicon Solar Cell ◽  
Energy Gap ◽  
Spectral Response ◽  
Solar Spectrum ◽  
Core Shell ◽  
Solar Cell Efficiency ◽  
Cell Efficiency ◽  
Electron Hole Pair ◽  
Pair Generation

Core-shell nanocrystals are utilized to improve vitality conversion efficiency of Si based solar cells. In the present work, a study of synthesis and characterization of photo luminescent, down-shifting, core-shell CdSe/CdS quantum dots is introduced. The QD,s absorb in the UV range (350nm) of the solar spectrum and emit photons with wavelengths centered at (574 nm). Calculated energy gap is (2.16 eV), which is well suited for Silicon absorption and electron-hole pair generation. The grain size is ranged between (1.814 and 3.456 nm). Results show that the cell efficiency is improved from (8.81%) (For a reference silicon solar cell) to (10.07%) (For a CdSe/CdS QD deposited directly on the surface of the solar cell). This improvement is referred to the spreading of the absorbed solar radiation over the spectral response of the Si solar cell.

Few-Layered MoS2 Nanostructures for Highly Efficient Visible Light Photocatalysis

NANO ◽  
2016 ◽  
Vol 11 (10) ◽  
pp. 1650114 ◽  
Author(s):  
Dan Li ◽  
Jianwei Li ◽  
Caiqin Han ◽  
Xinsheng Zhao ◽  
Haipeng Chu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Electrochemical Impedance ◽  
X Ray Diffraction ◽  
Electron Hole ◽  
Electrochemical Impedance Spectra ◽  
X Ray ◽  
Transmission Electron ◽  
Electron Hole Pair

Few-layered MoS2 nanostructures were successfully synthesized by a simple hydrothermal method without the addition of any catalysts or surfactants. Their morphology, structure and photocatalytic activity were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, electrochemical impedance spectra and UV-Vis absorption spectroscopy, respectively. These results show that the MoS2 nanostructures synthesized at 180[Formula: see text]C exhibit an optimal visible light photocatalytic activity (99%) in the degradation of Rhodamine B owing to the relatively easier adsorption of pollutants, higher visible light absorption and lower electron–hole pair recombination.

First-Principles Study on Electronic and Optical Properties in Pr-Doped Anatase TiO2

2014 ◽  
Vol 924 ◽  
pp. 260-268 ◽  
Author(s):  
Hao Chen ◽  
Lan Fang Yao ◽  
Song Lin Yang ◽  
Ya Qin Wang ◽  
Xing Liang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Photocatalytic Activity ◽  
First Principles ◽  
Energy Gap ◽  
Impurity Band ◽  
Anatase Tio2 ◽  
Electron Hole ◽  
Light Region ◽  
Overlap Population ◽  
Calculation Results

The crystal structures, band structures, density of states, charge density, overlap population and optical properties of pure anatase TiO2 and Pr-doped anatase TiO2 were studied by using the plane-wave pseudopotential method based on the first-principles. After Pr doping, the valence band and the conduction band moved down and became dense, energy gap became narrow and a impurity band which consists of Pr 4f states appeared. And the dipole moment got improved, which is good for the separate of the electron-hole pairs. These effectively overcome two huge shortcomings of TiO2. Besides, Pr-doped anatase TiO2 produced more carriers which have good transport properties and the absorption spectra of Pr-O bond appear in the region that the wavelength is longer. The calculation results of optical properties show that the absorption edge occured red shift, which means the photocatalytic activity of anatase TiO2 got remarkable improved during visible-light region. This conforms to the previous analysis. So the photocatalytic activity of anatase TiO2 got remarkable improved after Pr doping.

scholarly journals The Effect of Different Mixed Organic Solvents on the Properties of p(OPal-MMA) Gel Electrolyte Membrane for Lithium Ion Batteries

2018 ◽  
Vol 8 (12) ◽  
pp. 2587 ◽  
Author(s):  
Lanlan Tian ◽  
Mengkun Wang ◽  
Lian Xiong ◽  
Haijun Guo ◽  
Chao Huang ◽  
...  
Keyword(s):  
Specific Capacity ◽  
Mixed Solvents ◽  
Three Dimensional ◽  
Lithium Ion ◽  
Transference Number ◽  
Polymer Membrane ◽  
Electrochemical Performances ◽  
Electrolyte Membrane ◽  
Phase Inversion Technique ◽  
Key Factor

A solvent is a key factor during polymer membrane preparation, and it is directly related to application performance as a separator for lithium ion battery (LIB). In this study, different mixed solvents were employed to prepare polymer (p(OPal-MMA)) membranes by the phase inversion technique. The polymer membrane then absorbed liquid electrolytes to obtain gel electrolytes (GPEs). The surface morphologies and porosities of these membranes were investigated, and lithium ion transferences and electrochemical performances of these GPEs were also measured. The membrane displayed an interconnected three-dimensional framework structure with uniformly distributed pores when using DMF as a porogen. When combined with acetone as the component solvent, the prepared GPE displayed the largest lithium ion transference number (0.706), the highest porosity (42.6%) and ion conductivity (3.99 × 10−3 S/cm). Even when assembled as Li/GPE/LiFePO4 cell, it exhibited the highest initial specific capacity of 167 mAh/g and retained most capacity (162 mAh/g) after 50 cycles. The results presented here probably provide reference for choosing an appropriate mixed solvent in fabricating polymer membranes.

scholarly journals A Mini Review on Bismuth-Based Z-Scheme Photocatalysts

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5057
Author(s):  
Ruizhen Li ◽  
Hanyang Chen ◽  
Jianrong Xiong ◽  
Xiaoying Xu ◽  
Jiajia Cheng ◽  
...  
Keyword(s):  
Environmental Pollutants ◽  
Co2 Reduction ◽  
Pollutant Removal ◽  
Energy Utilization ◽  
Research Progress ◽  
Future Perspective ◽  
Synthesis Methods ◽  
Pollutants Removal ◽  
Photocatalytic Reactions ◽  
Redox Ability

Recently, the bismuth-based (Bi-based) Z-scheme photocatalysts have been paid great attention due to their good solar energy utilization capacity, the high separation rate of their photogenerated hole-electron pairs, and strong redox ability. They are considerably more promising materials than single semiconductors for alleviating the energy crisis and environmental deterioration by efficiently utilizing sunlight to motivate various photocatalytic reactions for energy production and pollutant removal. In this review, the traits and recent research progress of Bi-based semiconductors and recent achievements in the synthesis methods of Bi-based direct Z-scheme heterojunction photocatalysts are explored. The recent photocatalytic applications development of Bi-based Z-scheme heterojunction photocatalysts in environmental pollutants removal and detection, water splitting, CO2 reduction, and air (NOx) purification are also described concisely. The challenges and future perspective in the studies of Bi-based Z-scheme heterojunction photocatalysts are discussed and summarized in the conclusion of this mini review.

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