Application of Titanium Dioxide (TiO2) Based Photocatalytic Nanomaterials in Solar and Hydrogen Energy: A Short Review

2012 ◽  
Vol 712 ◽  
pp. 25-47 ◽  
Author(s):  
Amir Al-Ahmed ◽  
Bello Mukhtar ◽  
Safdar Hossain ◽  
S.M. Javaid Zaidi ◽  
S.U. Rahman
Keyword(s):  
Titanium Dioxide ◽  
Hydrogen Storage ◽  
Water Splitting ◽  
Electronic Band Structure ◽  
Structural Phase ◽  
Research Work ◽  
Size Variation ◽  
Minimum Size ◽  
Hydrogen Energy ◽  
Electronic Band

Tremendous amount of research work is going on Titanium dioxide (TiO2) based materials. These materials have many useful applications in our scientific and daily life and it ranges from photovoltaics to photocatalysis to photo-electrochromics, sensors etc.. All these applications can be divided into two broad categories such as environmental (photocatalysis and sensing) and energy (photovoltaics, water splitting, photo-/electrochromics, and hydrogen storage). Synthesis of TiO2nanoparticles with specific size and structural phase is crucial, for solar sell application. Monodispersed spherical colloids with minimum size variation (5% or less) is essential for the fabrication of photonic crystals. When sensitized with organic dyes or inorganic narrow band gap semiconductors, TiO2can absorb light into the visible light region and convert solar energy into electrical energy for solar cell applications. TiO2nanomaterials also have been widely studied for water splitting and hydrogen production due to their suitable electronic band structure given the redox potential of water. Again nanostructured TiO2has extensively been studied for hydrogen storage with good storage capacity and easy releasing procedure. All these issues and related finding will be discussed in this review.

scholarly journals Electronic structure, Mechanical and Thermodynamic properties of CoYSb (Y= Cr, Mo, W) half-Heusler compounds as potential spintronic materials

2021 ◽  
Author(s):  
O. T. Uto ◽  
J. O. Akinlami ◽  
S. Kenmoe ◽  
G. A. Adebayo
Keyword(s):  
Density Functional ◽  
Electronic Band Structure ◽  
Structural Phase ◽  
Covalent Bond ◽  
Stable Phase ◽  
Type I ◽  
Generalized Gradient ◽  
Electronic Density ◽  
Electronic Band ◽  
Half Metallic

Abstract The CoYSb (Y = Cr, Mo and W) compounds which are XYZ type half-Heusler alloys and also exist in the face centred cubic MgAgAs-type struc-ture conform to F ̄43m space group. In the present work, these compoundsare investigated in different atomic arrangements called, Type-I, Type-II andType-III phases, using Generalized Gradient Approximation (GGA) in the Density Functional Theory (DFT) implemented in QE (Quantum EspressoAb-Initio Simulation Package). The ferromagnetic state of these alloys is studied after investigating their stable structural phase. The calculated electronic band structure and the total electronic density of states indicated nearly half-metallic behaviour in CoMoSb with a possibility of being used in spintronic application, metallic in CoWSb and half-metallic in CoCrSb, with the minority spin band gap of 0.81 eV. Furthermore, the calculated mechanical properties predicted an anisotropic behaviour of these alloys in the stable phase. Finally, due to its high Debye temperature value, CoCrSb possesses a stronger covalent bond than CoMoSb and CoWSb, respectively.

scholarly journals Surface-Modified Titanium Dioxide Nanofibers with Gold Nanoparticles for Enhanced Photoelectrochemical Water Splitting

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 261 ◽  
Author(s):  
Van Nghia Nguyen ◽  
Minh Vuong Nguyen ◽  
Thi Hong Trang Nguyen ◽  
Minh Thuy Doan ◽  
Loan Le Thi Ngoc ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Gold Nanoparticles ◽  
Titanium Dioxide ◽  
Water Splitting ◽  
Xenon Lamp ◽  
Hydrogen Energy ◽  
Au Nps ◽  
X Ray ◽  
Tio2 Nanofiber ◽  
Surface Modified

High-stability, high-efficiency, and low-cost solar photoelectrochemical (PEC) water splitting has great potential for hydrogen-energy applications. Here, we report on gold/titanium dioxide (Au/TiO2) nanofiber structures grown directly on a conductive indium tin oxide substrate, and used as photoelectrodes in PEC cells for hydrogen generation. The titanium dioxide nanofibers (TiO2 NFs) are synthesized using electrospinning, and are surface-modified by the deposition of gold nanoparticles (Au NPs) using a simple photoreduction method. The structure and morphology of the materials were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The surface plasmon resonance (SPR) of the Au NPs was investigated by ultraviolet-visible (UV-Vis) diffuse reflectance spectroscopy. The PEC properties of the as-prepared photoelectrodes were measured. The obtained photoconversion efficiency of 0.52% under simulated-sunlight illumination by a 150 W xenon lamp of the Au/TiO2 NFs structure with 15 min UV irradiation for Au NP deposition was the highest value from comparable structures. Working photoelectrode stability was tested, and the mechanism of the enhanced PEC performance is discussed.

PRESSURE-INDUCED METALLIZATION AND SUPERCONDUCTIVITY IN InP AND InN

2011 ◽  
Vol 25 (04) ◽  
pp. 573-587
Author(s):  
K. IYAKUTTI ◽  
V. REJILA ◽  
M. RAJARAJESWARI ◽  
C. NIRMALA LOUIS ◽  
S. MAHALAKSHMI
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Structural Phase Transition ◽  
Electronic Band Structure ◽  
Indium Nitride ◽  
Structural Phase ◽  
Superconducting Transition ◽  
Electronic Band ◽  
Zinc Blende ◽  
Lmto Method

The electronic band structure, structural phase transition, metallization and superconducting transition of cubic zinc blende-type indium phosphide ( InP ) and indium nitride ( InN ), under pressure, are studied using TB-LMTO method. These indium compounds become metals and superconductors under high pressure but before that they undergo structural phase transition from ZnS to NaCl structure. The ground-state properties and band gap values are compared with the experimental and previous theoretical results. From our analysis, it is found that the metallization pressure increases with increase of lattice constant. The superconducting transition temperatures (Tc) of InP and InN are obtained as a function of pressure for both the ZnS and NaCl structures and these compounds are identified as pressure-induced superconductors. When pressure is increased Tc increases in both the normal ( ZnS ) and high pressure ( NaCl ) structures. The dependence of Tc on electron–phonon mass enhancement factor λ shows that InP and InN are electron–phonon mediated superconductors. The non-occurrence of metallization, phase transition and onset of superconductivity simultaneously in InP and InN are confirmed.

scholarly journals Study of Structural and Electronic Behavior of BeH2 as Hydrogen Storage Compound: An Ab Initio Approach

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Vikas Nayak ◽  
Suman Banger ◽  
U. P. Verma
Keyword(s):  
Hydrogen Storage ◽  
Electronic Properties ◽  
Density Functional ◽  
Correlation Energy ◽  
Electronic Band Structure ◽  
Unit Cell ◽  
Generalized Gradient ◽  
Hydrogen Atoms ◽  
Electronic Band ◽  
Cell Parameters

The quantum mechanical calculations based on density functional theory (DFT) have been performed to study ground state structural and electronic properties of BeH2 and along with doping of two (BeH2 + 2H) and four (BeH2 + 4H) hydrogen atoms. The generalized gradient approximation (GGA) has been employed for the exchange correlation energy. The most stable space group of BeH2 is Ibam. Its optimized equilibrium unit cell volume, bulk modulus and its first-order pressure derivative, and electronic properties have been obtained. Our predicted unit cell parameters for BeH2  a=9.2463 Å, b=4.2352 Å, and c=7.8464 Å are in very good agreement with the earlier reported experimental and theoretical results. The electronic band structure of BeH2 shows its behavior as an insulator. The stability of BeH2 along with doped hydrogen atoms increases, while the energy band gap decreases with the increase in number of doped hydrogen atoms. On these bases, we predict that BeH2 is a promising material for hydrogen storage.

Electronic band structure of titanium dioxide

1977 ◽  
Vol 15 (6) ◽  
pp. 3229-3235 ◽  
Author(s):  
N. Daude ◽  
C. Gout ◽  
C. Jouanin
Keyword(s):  
Titanium Dioxide ◽  
Band Structure ◽  
Electronic Band Structure ◽  
Electronic Band

Ab initio Electronic Band Structure Calculations for Beryllium Chalcogenides

1998 ◽  
Vol 12 (19) ◽  
pp. 1975-1984 ◽  
Author(s):  
G. Kalpana ◽  
G. Pari ◽  
A. Mookerjee ◽  
A. K. Bhattacharyya
Keyword(s):  
Bulk Modulus ◽  
Band Gap ◽  
Structural Transition ◽  
Electronic Band Structure ◽  
Local Density ◽  
Structural Phase ◽  
Experimental Results ◽  
Orbital Method ◽  
Electronic Band ◽  
Indirect Band Gap

The first principles tight-binding linear muffin-tin orbital method within the local density approximation (LDA) has been used to calculate the ground state properties structural phase transition and pressure dependence of the band gap of BeS, BeSe and BeTe. We have calculated the energy-volume relations for these compounds in the B3 and B8 phases. The calculated lattice parameters, bulk modulus and the pressure-volume relation were found to be in good agreement with the recent experimental results. We have also calculated the cohesive energy for them and they are consistent with the bulk modulus. The calculated B3 to B8 structural transition pressure for BeS, BeS and BeTe agree well with the experimental results. Our calculations show that these compounds are indirect band gap (Γ-X) semiconductors at ambient conditions. The calculated band gap values are found to be underestimated by 20–30% which is due to the usage of LDA. After the structural transition to the B8 phase BeS continues to be indirect band gap semiconductor and ultimately it becomes metallic above 100 GPa. BeSe and BeTe are metallic at B3 to B8 structural transition.

MgB2: Superconductivity and Pressure

2003 ◽  
Vol 17 (21) ◽  
pp. 3785-3806 ◽  
Author(s):  
A. K. M. A. Islam ◽  
F. N. Islam
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Structural Phase ◽  
Phonon Coupling ◽  
Electronic Band ◽  
Structural Bonding ◽  
New Material ◽  
Key Issues ◽  
Structure Density

The present work is an overview of the properties of the newly discovered MgB 2 carried out by us using first-principles density functional calculations as implemented in a program package, not used by other workers. Structural, bonding and elastic properties, phonon coupling, transition temperature, electronic band structure, density of states, charge-density and chemical bonding, electric field gradient are all considered for the new material at ambient and at higher pressures. New and interesting aspects including the pressure-induced structural phase transition in MgB 2 are also discussed. The calculations are compared with the available results and their implications are discussed which may help in understanding some key issues.

BAND STRUCTURE, METALLIZATION AND SUPERCONDUCTIVITY OF InP AND InN UNDER HIGH PRESSURE

2012 ◽  
Vol 11 (01) ◽  
pp. 19-33 ◽  
Author(s):  
A. AMAL RAJ ◽  
C. NIRMALA LOUIS ◽  
V. REJILA ◽  
K. IYAKUTTI
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Band Structure ◽  
Structural Phase Transition ◽  
Electronic Band Structure ◽  
Indium Nitride ◽  
Structural Phase ◽  
Superconducting Transition ◽  
Electronic Band ◽  
Lmto Method

The electronic band structure, structural phase transition, metallization and superconducting transition of cubic zinc blende type indium phosphide (InP) and indium nitride (InN), under pressure, are studied using FP-LMTO method. These indium compounds become metals and superconductors under high pressure but before that they undergo structural phase transition from ZnS to NaCl structure. The ground state properties and band gap values are compared with the experimental and previous theoretical results. From our analysis, it is found that the metallization pressure increases with increase of lattice constant. The superconducting transition temperatures (Tc) of InP and InN are obtained as a function of pressure for both the ZnS and NaCl structures and these compounds are identified as pressure induced superconductors. When pressure is increased Tc increases in both the normal ( ZnS ) and high pressure ( NaCl ) structures. The dependence of Tc on electron–phonon mass enhancement factor λ shows that InP and InN are electron–phonon mediated superconductors. The non-occurrence of metallization, phase transition and onset of superconductivity simultaneously in InP and InN is confirmed.

scholarly journals High Pressure Study of Structural and Electronic Properties of PbSe

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
P. Bhambhani ◽  
K. Kabra ◽  
B. K. Sharma ◽  
G. Sharma
Keyword(s):  
High Pressure ◽  
Electronic Properties ◽  
Energy Gap ◽  
Electronic Band Structure ◽  
Local Density ◽  
Structural Phase ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Structural And Electronic Properties ◽  
Direct Band

High pressure structural phase transition and electronic properties have been investigated using the linear combination of atomic orbitals (LCAO) method with two exchange-correlation approximations, the generalized gradient approximation (GGA) and local density approximation (LDA). The present study shows phase transitions from B1 to B27 and B27 to B2 at 6.24 GPa and 16.39 GPa, respectively. Lattice constant, bulk modulus, and energy gap of pressure-induced PbSe are found to be in good agreement with previous theoretical and experimental results. Variation of electronic band structure with pressure shows direct band gap along L point of the Brillouin zone.

BAND STRUCTURE, METALLIZATION, AND SUPERCONDUCTIVITY OF GaAs AND InAs UNDER HIGH PRESSURE

2007 ◽  
Vol 06 (04) ◽  
pp. 833-843 ◽  
Author(s):  
A. AMALRAJ ◽  
C. NIRMALA LOUIS ◽  
SR. GERARDIN JAYAM
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Band Structure ◽  
Structural Phase Transition ◽  
Electronic Band Structure ◽  
Structural Phase ◽  
Normal Structure ◽  
Superconducting Transition ◽  
Electronic Band ◽  
Phase Transition Pressure

The electronic band structure, metallization, structural phase transition, and superconductivity of cubic zinc blende type GaAs and InAs are investigated. The equilibrium lattice constant, bulk modulus, and the phase transition pressure at which the compounds undergo structural phase transition from ZnS to NaCl are predicted from the total energy calculations. The density of states at the Fermi level (N(E F )) get enhanced after metallization, which leads to the superconductivity in GaAs and InAs . The superconducting transition temperatures (T c ) of GaAs and InAs are obtained as a function of pressure for both the ZnS and NaCl structures. GaAs and InAs come under the class of pressure-induced superconductors. When pressure is increased T c increases in both the normal and high pressure-structures. The dependence of T c on electron–phonon mass enhancement factor λ shows that GaAs and InAs are electron–phonon-mediated superconductors. Also, it is found that GaAs and InAs retained in their normal structure under high pressure give appreciably high T c .

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