Band engineering and charge separation in the Mo1−xWxS2/TiO2heterostructure by alloying: first principle prediction

Faraji, Monireh; Sabzali, Mehdi; Yousefzadeh, Samira; Sarikhani, N.; Ziashahabi, Azin; Zirak, Mohammad; Moshfegh, A.Z.

doi:10.1039/c5ra00330j

Cited by 29 publications

(14 citation statements)

References 44 publications

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“…A large difference in

D

will reduce the recombination rate of charge carriers to enhance their mobility . As shown in Table , the D value is observed to be higher in the ternary Fe/C/S‐doped TiO 2 systems than in the un‐doped TiO 2 , signifying an increased lifetime of charge carriers in the ternary Fe/C/S‐doped TiO 2 systems, which indicates an enhanced mobility and separation of photogenerated charge carriers.…”

Section: Resultsmentioning

confidence: 91%

Understanding the synergistic effects, optical and electronic properties of ternary Fe/C/S‐doped TiO₂ anatase within the DFT + U approach

Opoku

Govender

Sittert

et al. 2017

Int J of Quantum Chemistry

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Although TiO2 is an efficient photocatalyst, its large band gap limits its photocatalytic activity only to the ultraviolet region. An experimentally synthesized ternary Fe/C/S‐doped TiO2 anatase showed improved visible light photocatalytic activity. However, a theoretical study of the underlying mechanism of the enhanced photocatalytic activity and the interaction of ternary Fe/C/S‐doped TiO2 has not yet been investigated. In this study, the defect formation energy, electronic structure and optical property of TiO2 doped with Fe, C, and S are investigated in detail using the density functional theory + U method. The calculated band gap (3.21 eV) of TiO2 anatase agree well with the experimental band gap (3.20 eV). The defect formation energy shows that the co‐ and ternary‐doped systems are thermodynamically favorable under oxygen‐rich condition. Compared to the undoped TiO2, the absorption edge of the mono‐, co‐, and ternary‐doped TiO2 is significantly enhanced in the visible light region. We have shown that ternary doping with C, S, and Fe induces a clean band structure without any impurity states. Moreover, the ternary Fe/C/S‐doped TiO2 exhibit an enhanced photocatalytic activity, a smaller band gap and negative formation energy compared to the mono‐ and co‐doped systems. Moreover, the band edges of Fe/C/S‐doped TiO2 align well with the redox potentials of water, which shows that the ternary Fe/C/S‐doped TiO2 is promising photocatalysts to split water into hydrogen and oxygen. These findings rationalize the available experimental results and can assist the design of TiO2‐based photocatalyst materials.

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“…A large difference in

D

Section: Resultsmentioning

confidence: 91%

Understanding the synergistic effects, optical and electronic properties of ternary Fe/C/S‐doped TiO₂ anatase within the DFT + U approach

Opoku

Govender

Sittert

et al. 2017

Int J of Quantum Chemistry

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“…Since the hole mass for A 2 AgRhCl 6 is comparable to that of other systems (Wang Z. et al, 2019), the contribution of the holes to charge transfer is unlikely to be very large (Park, 2019) and the lifetime of the charge carriers for these semiconductors is likely to be determined by electron-electron collisions (Kao, 2004;Morkoc, 2009;Fu and Zhao, 2018). The ratio m * e /m h * provides the nature of electron-hole (e-h) pair stability in a recombination process (Zhang et al, 2012a,b;Dong et al, 2015;Faraji et al, 2015;De Lazaro et al, 2017;Opoku et al, 2017). In general, the larger the m * e /m h * ratio, the smaller the rate of recombination of the photoinduced charges.…”

Section: Nature Of Effective Masses and Their Mobilitymentioning

confidence: 96%

The Cs2AgRhCl6 Halide Double Perovskite: A Dynamically Stable Lead-Free Transition-Metal Driven Semiconducting Material for Optoelectronics

Varadwaj

Marques

2020

Front. Chem.

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A-Site doping with alkali ions, and/or metal substitution at the B and B ′-sites, are among the key strategies in the innovative development of A 2 BB ′ X 6 halide double perovskite semiconducting materials for application in energy and device technologies. To this end, we have investigated an intriguing series of five halide-based non-toxic systems, A 2 AgRhCl 6 (A = Li, Na, K, Rb, and Cs), using density functional theory at the SCAN-rVV10 level. The lattice stability and bonding properties emanating from this study of A 2 AgRhCl 6 matched well with those that have already been synthesized, characterized and discussed [viz. Cs 2 AgBiX 6 (X = Cl, Br)]. Exploration of traditional and recently proposed tolerance factors has enabled us to identify A 2 AgRhCl 6 (A = K, Rb and Cs) as stable double perovskites. The band structure and density of states calculations suggested that the electronic transition from the top of the valence band [Cl(3p)+Rh(4d)] to the bottom of the conduction band [(Cl(3p)+Rh(4d)] is inherently direct at the X-point of the first Brillouin zone. The (non-spin polarized) bandgap of these materials was found in the range 0.57-0.65 eV with SCAN-rVV10, which were substantially smaller than those computed with hybrid HSE06 and PBE0, and quasi-particle GW methods. This, together with the appreciable refractive index and high absorption coefficient in the region covering the range 1.0-4.5 eV, enabled us to demonstrate that A 2 AgRhCl 6 (A = K, Rb, and Cs) are likely candidate materials for photoelectric applications. The results of our phonon calculations at the harmonic level suggested that the Cs 2 AgRhCl 6 is the only system that is dynamically stable (no imaginary frequencies found around the high symmetry lines of the reciprocal lattice), although the elastic moduli properties suggested all five systems examined are mechanically stable. Keywords: A 2 AgRhCl 6 halide double perovskites, first-principles studies, optoelectronic properties, geometrical, dynamical and mechanical stabilities, DOS and band structures Varadwaj and Marques Stable Halide Double Perovskites

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“…In DFT calculation, the standard GGA exchange-correlation is known to give an underestimated value of the pristine MoS 2 band gap [15]. The Heyd, Scuseria, and Ernzerhof exchange-correlation functional (HSE06) [16] has been proven to accurately predict the MoS 2 band gap values close to experimental values [17]. In this study, we compare the band gap value obtained using GGA exchange-correlation with the band gap obtained using HSE06 for the Te line-ordered alloys.…”

Section: Introductionmentioning

confidence: 99%

First-principles studies of Te line-ordered alloys in a MoS 2 monolayer

Andriambelaza

Mapasha

Chetty

2018

Physica B: Condensed Matter

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The thermodynamic stability, structural and electronic properties of Te lineordered alloys are investigated using density functional theory (DFT) methods. Thirty four possible Te line-ordered alloy configurations are found in a 5 × 5 supercell of a MoS 2 monolayer. The calculated formation energies show that the Te line-ordered alloy configurations are thermodynamically stable at 0K and agree very well with the random alloys. The lowest energy configurations at each concentration correspond to the configuration where the Te atom rows are far apart from each other (avoiding clustering) within the supercell. The variation of the lattice constant at different concentrations obey Vegard's law. The Te line-ordered alloys fine tune the band gap of a MoS 2 monolayer although deviating from linearity behavior. Our results suggest that the Te line-ordered alloys can be an effective way to modulate the band gap of a MoS 2 monolayer for nanoelectronic, optoelectronic and nanophotonic applications.

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Band engineering and charge separation in the Mo_1−xW_xS₂/TiO₂heterostructure by alloying: first principle prediction

Cited by 29 publications

References 44 publications

Understanding the synergistic effects, optical and electronic properties of ternary Fe/C/S‐doped TiO₂ anatase within the DFT + U approach

Understanding the synergistic effects, optical and electronic properties of ternary Fe/C/S‐doped TiO₂ anatase within the DFT + U approach

The Cs2AgRhCl6 Halide Double Perovskite: A Dynamically Stable Lead-Free Transition-Metal Driven Semiconducting Material for Optoelectronics

First-principles studies of Te line-ordered alloys in a MoS 2 monolayer

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Band engineering and charge separation in the Mo1−xWxS2/TiO2heterostructure by alloying: first principle prediction

Cited by 29 publications

References 44 publications

Understanding the synergistic effects, optical and electronic properties of ternary Fe/C/S‐doped TiO2 anatase within the DFT + U approach

Understanding the synergistic effects, optical and electronic properties of ternary Fe/C/S‐doped TiO2 anatase within the DFT + U approach

The Cs2AgRhCl6 Halide Double Perovskite: A Dynamically Stable Lead-Free Transition-Metal Driven Semiconducting Material for Optoelectronics

First-principles studies of Te line-ordered alloys in a MoS 2 monolayer

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Band engineering and charge separation in the Mo_1−xW_xS₂/TiO₂heterostructure by alloying: first principle prediction

Understanding the synergistic effects, optical and electronic properties of ternary Fe/C/S‐doped TiO₂ anatase within the DFT + U approach

Understanding the synergistic effects, optical and electronic properties of ternary Fe/C/S‐doped TiO₂ anatase within the DFT + U approach