scholarly journals Interband Absorption in Few-Layer Graphene Quantum Dots: Effect of Heavy Metals

Materials ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1217 ◽  
Author(s):  
Ivan Shtepliuk ◽  
Rositsa Yakimova

Monolayer, bilayer, and trilayer graphene quantum dots (GQDs) with different binding abilities to elemental heavy metals (HMs: Cd, Hg, and Pb) were designed, and their electronic and optical properties were investigated theoretically to understand deeply the optical response under heavy metal exposure. To gain insight into the nature of interband absorption, we performed density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations for thickness-varying GQDs. We found that the interband absorption in GQDs can be efficiently tuned by controlling the thickness of GQDs to attain the desirable coloration of the interacting complex. We also show that the strength of the interaction between GQDs and Cd, Hg, and Pb is strongly dependent on the number of sp2-bonded layers. The results suggest that the thickness of GQDs plays an important role in governing the hybridization between locally-excited (LE) and charge-transfer (CT) states of the GQDs. Based on the partial density-of-states (DOS) analysis and in-depth knowledge of excited states, the mechanisms underlying the interband absorption are discussed. This study suggests that GQDs would show an improved sensing performance in the selective colorimetric detection of lead by the thickness control.

2017 ◽  
Vol 5 (24) ◽  
pp. 5984-5993 ◽  
Author(s):  
Jianguang Feng ◽  
Hongzhou Dong ◽  
Liyan Yu ◽  
Lifeng Dong

The effects of five types of oxygen-containing functional groups (–COOH, –COC–, –OH, –CHO, and –OCH3) on graphene quantum dots (GQDs) are investigated using time-dependent density functional theory (TD-DFT).


2015 ◽  
Vol 17 (26) ◽  
pp. 17413-17420 ◽  
Author(s):  
Guilherme Colherinhas ◽  
Eudes Eterno Fileti ◽  
Vitaly V. Chaban

In this work, we apply density functional theory to study the effect of neutral ionic clusters adsorbed on the GQD surface. We conclude that both the HOMO and the LUMO of GQDs are very sensitive to the presence of ions and to their distance from the GQD surface. However, the alteration of the band gap itself is modest, as opposed to the case of free ions (recent reports). Our work fosters progress in modulating electronic properties of nanoscale carbonaceous materials.


2019 ◽  
Vol 13 (04) ◽  
pp. 1
Author(s):  
Miguel Ojeda Martínez ◽  
Arturo Nascir Pérez Martínez ◽  
Víctor Manuel Rentería Tapia ◽  
Jose Luis Cuevas Figueroa ◽  
Duncan John Mowbray ◽  
...  

2019 ◽  
Vol 7 (40) ◽  
pp. 6156-6171 ◽  
Author(s):  
Morteza Vatanparast ◽  
Zahra Shariatinia

The role of different N-functionalities was investigated on the drug delivery performance of N-GQDs. Results suggested that the center N-GQD had a better performance than the pristine and edge N-GQDs.


Author(s):  
Shun-Chiao Chan ◽  
Yu-Lin Cheng ◽  
Bor Kae Chang ◽  
Che-Wun Hong

The near-infrared light (NIR) absorption of nitrogen-doped graphene quantum dots (NGQDs) containing different N-doping sites is systematically investigated with density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations...


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