Electrochemical probing of carbon quantum dots: not suitable for a single electrode material

RSC Advances ◽  
2015 ◽  
Vol 5 (130) ◽  
pp. 107270-107275 ◽  
Author(s):  
Xinnan Jia ◽  
Xiaobo Ji
Keyword(s):  
Quantum Dots ◽  
Electrochemical Properties ◽  
Functional Groups ◽  
Electrode Material ◽  
Negative Impact ◽  
Carbon Quantum Dots ◽  
High Oxygen ◽  
Oxygen Functional Groups ◽  
Better Than

We demonstrate that the easy aggregation, rapid stacking and high oxygen-functional groups of GQDs have a negative impact on the electrochemical properties. GQDs are no better than graphene as an excellent single electrode material.

3D hierarchical porous N-doped carbon quantum dots/vanadium nitride hybrid microflowers as a superior electrode material toward high-performance asymmetric capacitive deionization

2021 ◽  
Author(s):  
Jingxuan Zhao ◽  
Zhibo Zhao ◽  
Yang Sun ◽  
Xiangdong Ma ◽  
Meidan Ye ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Electrode Material ◽  
High Performance ◽  
Carbon Nanomaterials ◽  
Electrode Materials ◽  
Carbon Quantum Dots ◽  
Vanadium Nitride ◽  
Capacitive Deionization ◽  
Hierarchical Porous

Taking into account of time-confusing preparation processing and unsatisfied desalination capacity of carbon nanomaterials, exploring efficient electrode materials remains a great challenge for practical capacitive deionization (CDI) application. In this...

scholarly journals Synthesis and Properties of Nitrogen-Doped Carbon Quantum Dots Using Lactic Acid as Carbon Source

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 466
Author(s):  
Kaixin Chang ◽  
Qianjin Zhu ◽  
Liyan Qi ◽  
Mingwei Guo ◽  
Woming Gao ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Lactic Acid ◽  
Fluorescence Quenching ◽  
Functional Groups ◽  
Fluorescence Intensity ◽  
Carbon Quantum Dots ◽  
Nitrogen Doped ◽  
Ph Values ◽  
Wide Range ◽  
Nitrogen Doped Carbon

Nitrogen-doped carbon quantum dots (N-CQDs) were synthesized in a one-step hydrothermal technique utilizing L-lactic acid as that of the source of carbon and ethylenediamine as that of the source of nitrogen, and were characterized using dynamic light scattering, X-ray photoelectron spectroscopy ultraviolet-visible spectrum, Fourier-transformed infrared spectrum, high-resolution transmission electron microscopy, and fluorescence spectrum. The generated N-CQDs have a spherical structure and overall diameters ranging from 1–4 nm, and their surface comprises specific functional groups such as amino, carboxyl, and hydroxyl, resulting in greater water solubility and fluorescence. The quantum yield of N-CQDs (being 46%) is significantly higher than that of the CQDs synthesized from other biomass in literatures. Its fluorescence intensity is dependent on the excitation wavelength, and N-CQDs release blue light at 365 nm under ultraviolet light. The pH values may impact the protonation of N-CQDs surface functional groups and lead to significant fluorescence quenching of N-CQDs. Therefore, the fluorescence intensity of N-CQDs is the highest at pH 7.0, but it decreases with pH as pH values being either more than or less than pH 7.0. The N-CQDs exhibit high sensitivity to Fe3+ ions, for Fe3+ ions would decrease the fluorescence intensity of N-CQDs by 99.6%, and the influence of Fe3+ ions on N-CQDs fluorescence quenching is slightly affected by other metal ions. Moreover, the fluorescence quenching efficiency of Fe3+ ions displays an obvious linear relationship to Fe3+ concentrations in a wide range of concentrations (up to 200 µM) and with a detection limit of 1.89 µM. Therefore, the generated N-CQDs may be utilized as a robust fluorescence sensor for detecting pH and Fe3+ ions.

Origin of green luminescence in carbon quantum dots: specific emission bands originate from oxidized carbon groups

2018 ◽  
Vol 42 (6) ◽  
pp. 4603-4611 ◽  
Author(s):  
Zhiguo Sun ◽  
Xiaoming Li ◽  
Ye Wu ◽  
Changting Wei ◽  
Haibo Zeng
Keyword(s):  
Quantum Dots ◽  
Functional Groups ◽  
Surface State ◽  
Carbon Quantum Dots ◽  
Green Luminescence ◽  
Oxidized Carbon

This study demonstrates that the surface state functional groups are responsible for green waveband originating from CDs.

scholarly journals Enhancement of the electrochemical properties of commercial coconut shell-based activated carbon by H 2 O dielectric barrier discharge plasma

2019 ◽  
Vol 6 (2) ◽  
pp. 180872 ◽  
Author(s):  
Xin Wang ◽  
Xiaoyan Zhou ◽  
Weimin Chen ◽  
Minzhi Chen ◽  
Chaozheng Liu
Keyword(s):  
Electrochemical Properties ◽  
Specific Capacitance ◽  
Functional Groups ◽  
Discharge Plasma ◽  
Barrier Discharge ◽  
Plasma Modification ◽  
Dielectric Barrier Discharge Plasma ◽  
Dielectric Barrier ◽  
Oxygen Functional Groups ◽  
Barrier Discharge Plasma

Commercial coconut shell-based activated carbon (CSAC) has low specific capacitance and specific capacitance retention owing to its undeveloped pore structure and low proportion of heteroatoms. In this study, dielectric barrier discharge plasma was used to enhance the specific capacitance and rate capability of CSAC. H 2 O was used as an excited medium to introduce oxygen functional groups. The physico-chemical properties of CSAC and CSAC modified by H 2 O plasma (HCSAC) were revealed by automated surface area and pore size analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. Electrochemical work was applied to investigate the electrochemical properties of CSAC and HCSAC. The results obtained showed that plasma modification improved the specific capacitance of CSAC by 64.8% (current density, 1 A g −1 ; electrolyte, 6 M KOH solution) within 100 s. This result is ascribed to the oxygen functional groups introduced to the surface of CSAC. It can also improve the hydrophilicity and wettability of the carbon surface leading to an increase from 76.7% to 84.6% in specific capacitance retention. Furthermore, H 2 O plasma modification can introduce oxygen functional groups without destroying the initial pore structures of CSAC. In summary, we provide a simple, fast, environment-friendly modification method to enhance the electrochemical properties of CSAC.

How functional groups influence the ROS generation and cytotoxicity of graphene quantum dots

2017 ◽  
Vol 53 (76) ◽  
pp. 10588-10591 ◽  
Author(s):  
Ya Zhou ◽  
Hanjun Sun ◽  
Faming Wang ◽  
Jinsong Ren ◽  
Xiaogang Qu
Keyword(s):  
Quantum Dots ◽  
Functional Groups ◽  
Graphene Quantum Dots ◽  
Ros Generation ◽  
Hydroxyl Groups ◽  
Carbonyl Groups ◽  
Oxygen Functional Groups

Herein we selectively deactivate the ketonic carbonyl, carboxylic, or hydroxyl groups on GQDs and compare their ROS generation ability. The ROS generation ability of GQDs is closely related to these oxygen functional groups, especially for the ketonic carbonyl groups.

Green Synthesized Carbon Quantum Dots/Cobalt Sulfide Nanocomposite as Efficient Electrode Material for Supercapacitors

2021 ◽  
Author(s):  
Nasser Arsalani ◽  
Laleh Saleh Ghadimi ◽  
Iraj Ahadzadeh ◽  
Amin Goljanian Tabrizi ◽  
Thomas Nann
Keyword(s):  
Quantum Dots ◽  
Electrode Material ◽  
Carbon Quantum Dots ◽  
Cobalt Sulfide

scholarly journals Localized Surface Plasmon Resonance Decorated with Carbon Quantum Dots and Triangular Ag Nanoparticles for Chlorophyll Detection

Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 35
Author(s):  
Nur Afifah Ahmad Nazri ◽  
Nur Hidayah Azeman ◽  
Mohd Hafiz Abu Bakar ◽  
Nadhratun Naiim Mobarak ◽  
Yunhan Luo ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Surface Plasmon Resonance ◽  
Detection Limit ◽  
Functional Groups ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Linear Response ◽  
Localized Surface Plasmon Resonance ◽  
Carbon Quantum Dots ◽  
Localized Surface Plasmon

This paper demonstrates carbon quantum dots (CQDs) with triangular silver nanoparticles (AgNPs) as the sensing materials of localized surface plasmon resonance (LSPR) sensors for chlorophyll detection. The CQDs and AgNPs were prepared by a one-step hydrothermal process and a direct chemical reduction process, respectively. FTIR analysis shows that a CQD consists of NH2, OH, and COOH functional groups. The appearance of C=O and NH2 at 399.5 eV and 529.6 eV in XPS analysis indicates that functional groups are available for adsorption sites for chlorophyll interaction. A AgNP–CQD composite was coated on the glass slide surface using (3-aminopropyl) triethoxysilane (APTES) as a coupling agent and acted as the active sensing layer for chlorophyll detection. In LSPR sensing, the linear response detection for AgNP–CQD demonstrates R2 = 0.9581 and a sensitivity of 0.80 nm ppm−1, with a detection limit of 4.71 ppm ranging from 0.2 to 10.0 ppm. Meanwhile, a AgNP shows a linear response of R2 = 0.1541 and a sensitivity of 0.25 nm ppm−1, with the detection limit of 52.76 ppm upon exposure to chlorophyll. Based on these results, the AgNP–CQD composite shows a better linearity response and a higher sensitivity than bare AgNPs when exposed to chlorophyll, highlighting the potential of AgNP–CQD as a sensing material in this study.

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