Role of magnesium in band gap engineering of sub-monolayer type-II ZnTe quantum dots embedded in ZnSe

A cluster/semiconductor model is built for exploring the role of noble metal clusters in a photocatalytic system. The incorporation of an atomically precise nanocluster, e.g. Ag44(SR)30, onto a large band gap semiconductor such as TiO2 allows to obtain a clear interface and thus simplify the system. The composite is employed for photocatalytic H2 generation. It’s found that changing the light source from visible light to simulated sunlight leads to an enhancement by three orders of magnitude. The H2 production rate reaches 7.4 mmol/h/gcatalyst which is five times higher than that of Ag nanoparticles modified TiO2 and even comparable to that of the similar conditioned Pt nanoparticle modified TiO2. Energy band alignment and transient absorption spectroscopy, together with other studies, reveal that the role of the metal clusters is different from both organometallic complexes and plasmonic-nanoparticles. A type-II heterojunction charge transfer route is achieved under UV-vis irradiation, in which the cluster serves as small band gap semiconductor. The type-II photosystem has a more efficient charge separation ability, which contributes significantly to the enhanced catalytic performance. This finding endows the clusters a broad platform as cocatalysts rather than merely photosensitizers in the applications of light energy conversion.

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Band gap engineering and spatial confinement of optical phonon in ZnO quantum dots

Applied Physics Letters ◽

10.1063/1.2218775 ◽

2006 ◽

Vol 88 (26) ◽

pp. 263117 ◽

Cited By ~ 84

Author(s):

Kuo-Feng Lin ◽

Hsin-Ming Cheng ◽

Hsu-Cheng Hsu ◽

Wen-Feng Hsieh

Keyword(s):

Quantum Dots ◽

Band Gap ◽

Optical Phonon ◽

Spatial Confinement ◽

Band Gap Engineering ◽

Zno Quantum Dots

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Rapid and One-Pot Synthesis of Self-Assembled CdSe Quantum Dots Functionalized with β-Cyclodextrin: Reduced Cytotoxicity and Band Gap Engineering

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2015.10597 ◽

2015 ◽

Vol 15 (12) ◽

pp. 9341-9357 ◽

Cited By ~ 9

Author(s):

Apurav Guleria ◽

Madhab C. Rath ◽

Ajay K. Singh ◽

Soumyakanti Adhikari

Keyword(s):

Quantum Dots ◽

Band Gap ◽

Cdse Quantum Dots ◽

One Pot ◽

Band Gap Engineering ◽

One Pot Synthesis ◽

Self Assembled

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Optical and Electron Correlation Effects in Silicon Quantum Dots

Journal of Metastable and Nanocrystalline Materials ◽

10.4028/www.scientific.net/jmnm.23.129 ◽

2005 ◽

Vol 23 ◽

pp. 129-132 ◽

Cited By ~ 2

Author(s):

S.K. Ghoshal ◽

K.P. Jain ◽

R. Elliott

Keyword(s):

Quantum Dots ◽

Band Gap ◽

Surface Passivation ◽

Surface States ◽

Hydrogen Atoms ◽

Basis Expansion ◽

Electron Correlation Effects ◽

Homo Lumo ◽

Pseudo Potential

We study (through computer simulation) the variation of the band gap as a function of sizes and shapes of small Silicon (Si) dots using pseudo-potential approach. We have used empirical pseudo-potential Hamiltonian and a plane wave basis expansion and a basic tetrahedral structure. It is found that the gap decreases for increasing dot size. Furthermore, the band gap increases as much as 0.13eV on passivation the surface of the dot with hydrogen. So both quantum confinement and surface passivation determine the optical and electronic properties of Si quantum dots. Visible luminescence is probably due to radiative recombination of electrons and holes in the quantum confined nanostructures. The effect of passivation of the surface dangling bonds by hydrogen atoms and the role of surface states on the gap energy as well as on the HOMO-LUMO states has also been examined. We have investigated the entire energy spectrum starting from the very low lying ground state to the very high lying excited states for silicon dots having 5, 18, 17 and 18 atoms. The results for the size dependence of the HOMO-LUMO gap and the wave functions for the bonding-antibonding states are presented and the importance of the confinement and the role of hydrogen passivation on the confinement are also discussed.

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Insights into Charge Transfer at the Cluster/semiconductor Interface for In-Depth Understanding the Role of Atomically Precise Silver Cluster

10.26434/chemrxiv.11012369 ◽

2019 ◽

Author(s):

Yu Wang ◽

Xiao-He Liu ◽

Qiankun Wang ◽

Martin Quick ◽

Sergey Kovalenko ◽

...

Keyword(s):

Charge Transfer ◽

Band Gap ◽

Metal Clusters ◽

Silver Cluster ◽

Organometallic Complexes ◽

Band Alignment ◽

Transient Absorption Spectroscopy ◽

Type Ii ◽

Semiconductor Interface

A cluster/semiconductor model is built for exploring the role of noble metal clusters in a photocatalytic system. The incorporation of an atomically precise nanocluster, e.g. Ag44(SR)30, onto a large band gap semiconductor such as TiO2 allows to obtain a clear interface and thus simplify the system. The composite is employed for photocatalytic H2 generation. It’s found that changing the light source from visible light to simulated sunlight leads to an enhancement by three orders of magnitude. The H2 production rate reaches 7.4 mmol/h/gcatalyst which is five times higher than that of Ag nanoparticles modified TiO2 and even comparable to that of the similar conditioned Pt nanoparticle modified TiO2. Energy band alignment and transient absorption spectroscopy, together with other studies, reveal that the role of the metal clusters is different from both organometallic complexes and plasmonic-nanoparticles. A type-II heterojunction charge transfer route is achieved under UV-vis irradiation, in which the cluster serves as small band gap semiconductor. The type-II photosystem has a more efficient charge separation ability, which contributes significantly to the enhanced catalytic performance. This finding endows the clusters a broad platform as cocatalysts rather than merely photosensitizers in the applications of light energy conversion.

Download Full-text