Article
Nanoscience & Nanotechnology
Yifeng Xiang, Junxue Chen, Xi Tang, Ruxue Wang, Qiwen Zhan, Joseph R. Lakowicz, Douguo Zhang
Summary: Placing an ultrathin silver nanowire with a diameter less than 100 nm on a photonic band gap structure can excite surface plasmons that propagate along two side-walls, leading to the observation of two bright lines. Simulations suggest that the unique phase distribution of plasmons on the two side-walls of the silver nanowire is responsible for the bright lines observed in the far-field. The configuration reported in this work, combined with the sensing ability of surface plasmons to its environment, can function as a sensing platform to monitor environmental changes in the near-field region of the ultrathin nanowire.
Article
Chemistry, Multidisciplinary
Andreas Dreuw, Marvin Hoffmann
Summary: Molecules with inverted singlet-triplet gaps have gained attention for violating Hund's rule. The singlet-triplet gap approaches zero regardless of improvements in theoretical descriptions. It seems that the phenomenon tends to vanish as we observe closer.
FRONTIERS IN CHEMISTRY
(2023)
Article
Mathematics
Marco Bravin, Sarka Necasova
Summary: This study investigates the interaction between a small solid body and a viscous compressible fluid. The research focuses on a bounded three-dimensional domain, where the solid body is allowed to move freely according to Newton's laws. The paper presents a result of homogenization in the case of fluid-structure interaction under compressible conditions, showing that the fluid plus rigid body system converges to the compressible Navier-Stokes system as the size of the body approaches zero, subject to certain lower bound conditions on mass and inertia momentum. The study also provides a slight improvement on the understanding of the influence of a vanishing obstacle in a compressible fluid for gamma >= 6.
JOURNAL OF DIFFERENTIAL EQUATIONS
(2023)
Article
Mathematics, Applied
Tariq Mahmood, Zhaoyang Shang, Mei Sun
Summary: The research investigates the initial-boundary value problem for one-dimensional hydrodynamics equations of compressible nematic liquid crystal material. A global strong solution independent of eta is established under large initial data and vacuum conditions. Furthermore, the vanishing elastic limit is justified by convergence rates in L2 as the elastic limit parameter eta approaches zero. These results are achieved through the utilization of effective viscous flux, the equations' structure, and the material derivative.
MATHEMATICAL METHODS IN THE APPLIED SCIENCES
(2023)
Article
Mathematics, Applied
Qin Duan, Yuelong Xiao, Zhouping Xin
Summary: This paper investigates the solvability, regularity, and the vanishing dissipation limit of solutions to the three-dimensional viscous magnetohydrodynamic (MHD) equations in bounded domains. It is shown that there is a global weak solution for a general smooth domain, and for a flat domain, a strong solution with higher-order uniform regularity is established, converging asymptotically to the solution of the ideal MHD equation as the dissipations tend to zero.
SCIENCE CHINA-MATHEMATICS
(2022)
Article
Mathematics
Zhaonan Luo, Wei Luo, Zhaoyang Yin
Summary: The paper investigates the inviscid limit for the strong solutions of the finite extensible nonlinear elastic (FENE) dumbbell model. It provides a uniform estimate for the solution in Besov spaces using the Littlewood-Paley theory, and shows the continuity of the data-to-solution map. The convergence of the strong solution to an Euler system and a Fokker-Planck equation is proven, with convergence rates in Lebesgue spaces also obtained.
JOURNAL OF DIFFERENTIAL EQUATIONS
(2021)
Article
Physics, Multidisciplinary
Huan Pei, Changjian Yu, Jialu Qi, Jiaxin Zhao, Weifeng Peng, Jiale Zhang, Yong Wei
Summary: In this study, we investigated the influence of quantum tunneling on the plasmon-enhanced electric field and photoluminescence spectroscopy in the subnanometer nanogap between two adjacent Ag nanoparticles using the quantum-corrected method. Our results demonstrate the high sensitivity of the quantum-induced effect and nonlocal dielectric response to the separation distance. In cases of shorter separation distances, the localized fields start to decrease due to tunneling current short circuit, resulting in a substantial reduction in Raman enhancement and fluorescence intensity in narrowing gaps.
Article
Mathematics, Applied
Helena J. Nussenzveig Lopes, Christian Seis, Emil Wiedemann
Summary: This study demonstrates the strong convergence of vorticities in the vanishing viscosity limit for the incompressible Navier-Stokes equations on the two-dimensional torus, assuming certain initial conditions. It extends a previous result by Constantin, Drivas and Elgindi, which showed strong convergence in the case of infinity. The proof relies on the classical renormalisation theory of DiPerna-Lions and is surprisingly simple.
Article
Chemistry, Physical
Kun Liang, Jiaqi Guo, Fan Wu, Yuming Huang, Li Yu
Summary: This study presents a dynamic control method for transitioning from weak to strong coupling between condensed plasmon fields in ultracompact nanoantennas and tunable excitons in J-aggregates. Through the use of microfluidic techniques, the research successfully achieved flexible tuning of the coupled J-aggregate exciton number in isolated single Au@Ag nanocavities by adjusting dye concentrations, leading to the emergence and evolution of hybrid plexcitons with a Rabi splitting of up to 167 meV. Numerical calculations were also conducted to quantify the relationship between coupling strength and injected dye concentration, paving the way for highly controllable and ultracompact plasmon-exciton strong coupling systems.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Mathematics, Applied
Pritpal Matharu, Bartosz Protas, Tsuyoshi Yoneda
Summary: In this paper, we study the enstrophy dissipation in two-dimensional Navier-Stokes flows and investigate its behavior as the viscosity approaches zero. We solve an optimization problem numerically to find the initial conditions that locally maximize the enstrophy dissipation over a given time window. Multiple branches of local maximizers associated with different mechanisms for the amplification of enstrophy are observed. The maximum enstrophy dissipation is shown to be in quantitative agreement with the estimate by Ciampa et al. (2021), demonstrating the sharpness of this bound.
PHYSICA D-NONLINEAR PHENOMENA
(2022)
Article
Mathematics
Lei Peng, Jingyu Li, Ming Mei, Kaijun Zhang
Summary: In this paper, we investigate the behavior of solutions to the initial boundary value problem of the Hunter-Saxton equation in the half space as the viscosity approaches zero. By applying asymptotic analysis with multiple scales, we formally derive the equations for the boundary layer profiles. Subsequently, we analyze the well-posedness of these equations using the compactness argument. Additionally, we construct an accurate approximate solution and employ the energy method to obtain convergence results of the vanishing viscosity limit.
JOURNAL OF DIFFERENTIAL EQUATIONS
(2022)
Article
Nanoscience & Nanotechnology
Mahfujur Rahaman, Gwangwoo Kim, Kyung Yeol Ma, Seunguk Song, Hyeon Suk Shin, Deep Jariwala
Summary: The exciton control in transition metal dichalcogenides (TMDCs) and their heterostructures has fundamental importance for applications in optoelectronic and photonic devices. In this study, the behavior of intra- and interlayer excitons in TMDC heterobilayers under the quantum tunneling regime was explored using a metallic probe in an atomic force microscope. The results revealed significantly different exciton-plasmon coupling for intra- and interlayer excitons due to the orientation of the dipoles of the electron-hole pairs. The findings have important implications for near-field probing of excitonic materials in the strong-coupling regime.
NPJ 2D MATERIALS AND APPLICATIONS
(2023)
Article
Thermodynamics
Wei Gao, Yunfei Yan, Kaiming Shen, Lujing Huang, Ting Zhao, Bo Gao
Summary: The research shows that the cavity combustor with guide vanes has better combustion characteristics and higher temperature in the high-temperature zone compared to the traditional cavity combustor. It also has better preheating and ignition effects under different guide vane geometries.
Article
Mathematics, Applied
Ruizhao Zi
Summary: The study focuses on the vanishing viscosity limit of the 3D incompressible Oldroyd-B model, demonstrating the existence of a unique global solution with small analytic data as the coupling parameter approaches 1, corresponding to the inviscid case. It is also shown that the limit from the Oldroyd-B model to the inviscid case holds for all time, even when the nonlinear term is ignored.
ANNALES DE L INSTITUT HENRI POINCARE-ANALYSE NON LINEAIRE
(2021)
Article
Social Sciences, Interdisciplinary
Marko Ledic, Ivica Rubil
Summary: Wage is not the sole concern when evaluating job quality, with non-wage dimensions such as autonomy and work-life balance also playing a crucial role. This study introduces a framework for analyzing inter-group gaps in job quality using the concept of equivalent wage, which combines wage and non-wage job dimensions according to preferences. By decomposing the inter-group equivalent wage gap, the study shows that gender differences in equivalent wages are larger than wage differences due to advantages in non-wage dimensions for men and preference heterogeneity.
SOCIAL INDICATORS RESEARCH
(2021)
Article
Nanoscience & Nanotechnology
Alejandro Rodriguez, Karl-Philipp Schlichting, Dimos Poulikakos, Ming Hu
Summary: This study explores the energy landscape of gas molecules attempting permeation through graphene nanopores using density functional theory, determining the minimum energy permeation pathways and finding that pore diameter and chemical functionalization affect gas molecule permeation. Achieving positive permeation barriers required for high selectivity gas separation is found to be combined with postpermeation desorption barriers due to attractive van der Waals interactions.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Chemistry, Multidisciplinary
Abinash Tripathy, Cheuk Wing Edmond Lam, Diana Davila, Matteo Donati, Athanasios Milionis, Chander Shekhar Sharma, Dimos Poulikakos
Summary: Researchers have developed an ultrathin and conductive lubricant-infused surface architecture that greatly enhances heat transfer performance while resisting lubricant depletion, making it perform better in condensation processes.
Letter
Urology & Nephrology
Victoria Fox, Dimitrios Poulikakos
HEMODIALYSIS INTERNATIONAL
(2021)
Article
Urology & Nephrology
Dimitrios Poulikakos, Joanne Martin, Joanne Collier, David Lewis
Summary: U-Drain is a fixed drainage system for automated peritoneal dialysis that connects dialysis effluent outflow directly to the household drainage system, avoiding the use of drain bags. The pilot project showed increased patient satisfaction and an acceptable safety profile for the U-Drain technology.
PERITONEAL DIALYSIS INTERNATIONAL
(2022)
Article
Nanoscience & Nanotechnology
Hyunchul Park, Iwan Haechler, Gabriel Schnoering, Marco D. Ponte, Thomas M. Schutzius, Dimos Poulikakos
Summary: This study proposes a sustainable atmospheric water harvesting strategy using durable hydrogel sorbents, which operate based on a "ratcheting" mechanism activated by direct sunlight. The strategy improves the daily water productivity and demonstrates great potential to advance the water harvesting capabilities of related systems.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Chemistry, Multidisciplinary
Kartik Regulagadda, Julia Gerber, Thomas M. Schutzius, Dimos Poulikakos
Summary: This study investigates dynamic ice-elastomer interfacial events and reveals that the ice adhesion strength can vary by orders of magnitude due to the shear velocity. The underlying mechanism is elucidated by studying the detailed deformation fields of the elastomer.
MATERIALS HORIZONS
(2022)
Article
Physics, Applied
M. S. Gerlt, A. Paeckel, A. Pavlic, P. Rohner, D. Poulikakos, J. Dual
Summary: This study presents a method for two-dimensional metal microparticle focusing in a round glass capillary using bulk acoustic waves. By analyzing the change of acoustic streaming patterns, the mechanism for manipulating particles in the low-micrometer range is revealed. The results of this study are of great significance for various applications.
PHYSICAL REVIEW APPLIED
(2022)
Article
Chemistry, Multidisciplinary
Abinash Tripathy, Kartik Regulagadda, Cheuk Wing Edmond Lam, Matteo A. Donati, Athanasios Milionis, Chander Shekhar Sharma, Efstratios Mitridis, Thomas M. Schutzius, Dimos Poulikakos
Summary: The perfluorodecanethiol (PFDT) coating has demonstrated superior performance in terms of heat transfer and durability compared to other organic coatings such as perfluorodecyltriethoxysilane (PFDTS) and perfluorodecyl acrylate (PFDA). Despite being a monolayer, the PFDT coating exhibited dropwise condensation for at least 63 hours without deterioration, showcasing its hydrolytic stability. Additionally, the cost of thiol functionalization per area was the lowest among the surface hydrophobic treatments used in the study.
Article
Chemistry, Multidisciplinary
Luca Stendardo, Athanasios Milionis, George Kokkoris, Christos Stamatopoulos, Chander Shekhar Sharma, Raushan Kumar, Matteo Donati, Dimos Poulikakos
Summary: A new surface texture design strategy has been discovered through three-dimensional multiphase computational approach, which can achieve efficient droplet departure and enhance condensation heat-transfer efficiency and water harvesting capabilities.
Article
Nanoscience & Nanotechnology
Iwan Haechler, Nicole Ferru, Gabriel Schnoering, Efstratios Mitridis, Thomas M. Schutzius, Dimos Poulikakos
Summary: Counteracting surface fogging is crucial for eyewear, windows, and displays. An innovative transparent, sunlight-activated, photothermal coating is designed to inhibit fogging. This nanoscopically thin percolating gold layer coating achieves impressive performance in fog prevention and removal, even in cloudy conditions, with improved durability and integration capabilities.
NATURE NANOTECHNOLOGY
(2023)
Article
Chemistry, Multidisciplinary
Nafsika Chala, Xinyu Zhang, Tomaso Zambelli, Ziyi Zhang, Teseo Schneider, Daniele Panozzo, Dimos Poulikakos, Aldo Ferrari
Summary: Mechanical signals establish communication between mammalian cells and their environment. Cells exert forces and transmit them at focal adhesion points. External stimuli affect the adhesion-free cell surface. The integration of Fluidic Force Microscopy and confocal Traction Force Microscopy enables precise force probing of individual cells, allowing the investigation of cellular mechanisms in response to mechanical stimuli.
Article
Physics, Multidisciplinary
Henry Lambley, Gustav Graeber, Raphael Vogt, Leon C. C. Gaugler, Enea Baumann, Thomas M. M. Schutzius, Dimos Poulikakos
Summary: Supercooled droplet freezing on surfaces is a common phenomenon in nature and industry, but little is known about its effect on droplet-substrate interactions and the design of icephobic surfaces. This study investigates freezing of supercooled droplets on textured surfaces and identifies surface properties that promote ice expulsion. The study also explores mechanisms through which repellency falters and provides insights into the phenomenology of ice adhesion throughout freezing. The findings contribute to the design of icephobic surfaces for increased safety and sustainability in engineering applications.
Article
Multidisciplinary Sciences
Francesca Michela Pramotton, Lucien Cousin, Tamal Roy, Costanza Giampietro, Marco Cecchini, Cecilia Masciullo, Aldo Ferrari, Dimos Poulikakos
Summary: Mammalian cells respond to topographic cues from a substrate, with anisotropic features giving guidance. However, in the extracellular matrix, the presence of noise affects this guidance effect. This study introduces morphotaxis, a mechanism where fibroblasts and epithelial cells move according to gradients of topographic order distortion.
Article
Chemistry, Multidisciplinary
Panagiotis Sarkiris, Vassilios Constantoudis, Kosmas Ellinas, Cheuk Wing Edmond Lam, Athanasios Milionis, John Anagnostopoulos, Dimos Poulikakos, Evangelos Gogolides
Summary: Micro-nanoengineered superhydrophobic surfaces can enhance heat transfer by inducing the formation of highly mobile condensate droplets. The critical role of the correlation length of topography in designing these surfaces for heat transfer applications is demonstrated. A high correlation length value leads to increased space between surface structures, resulting in improved heat transfer coefficient and delayed flooding of the surface. Therefore, correlation length is a critical criterion for optimizing surfaces for condensation heat transfer.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
Sophie C. Lohmann, Abinash Tripathy, Athanasios Milionis, Anja Keller, Dimos Poulikakos
Summary: Driven by the threat of antimicrobial resistance, the design of intrinsically bactericidal surfaces has gained attention. The sizing and flexibility of pillar nanostructures play a crucial role in effective antibacterial functionality.
ACS APPLIED BIO MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Laetitia Bardet, Herve Roussel, Stefano Saroglia, Masoud Akbari, David Munoz-Rojas, Carmen Jimenez, Aurore Denneulin, Daniel Bellet
Summary: The thermal instability of silver nanowires leads to increased electrical resistance in AgNW networks. Understanding the relationship between structural and electrical properties of AgNW networks is crucial for their integration as transparent electrodes in flexible optoelectronics. In situ X-ray diffraction measurements were used to study the crystallographic evolution of Ag-specific Bragg peaks during thermal ramping, revealing differences in thermal and structural transitions between bare and SnO2-coated AgNW networks.
Article
Chemistry, Multidisciplinary
Nathalia Cancino-Fuentes, Arnau Manasanch, Joana Covelo, Alex Suarez-Perez, Enrique Fernandez, Stratis Matsoukis, Christoph Guger, Xavi Illa, Anton Guimera-Brunet, Maria V. Sanchez-Vives
Summary: This study provides a comprehensive characterization of graphene-based solution-gated field-effect transistors (gSGFETs) for brain recordings, highlighting their potential clinical applications.
Article
Chemistry, Multidisciplinary
Sikandar Aftab, Hailiang Liu, Dhanasekaran Vikraman, Sajjad Hussain, Jungwon Kang, Abdullah A. Al-Kahtani
Summary: This study examines the effects of hybrid nanoparticles made of NiO@rGO and NiO@CNT on the active layers of polymer solar cells and X-ray photodetectors. The findings show that these hybrid nanoparticles can enhance the charge carrier capacities and exciton dissociation properties of the active layers. Among the tested configurations, the NiO@CNT device demonstrates superior performance in converting sunlight into electricity, and achieves the best sensitivity for X-ray detection.
Article
Chemistry, Multidisciplinary
Hyo Jung Shin, Seung Gyu Choi, Fengrui Qu, Min-Hee Yi, Choong-Hyun Lee, Sang Ryong Kim, Hyeong-Geug Kim, Jaewon Beom, Yoonyoung Yi, Do Kyung Kim, Eun-Hye Joe, Hee-Jung Song, Yonghyun Kim, Dong Woon Kim
Summary: This study investigates the role of SOX9 in reactive astrocytes following ischemic brain damage using a PLGA nanoparticle plasmid delivery system. The results demonstrate that PLGA nanoparticles can reduce ischemia-induced neurological deficits and infarct volume, providing a potential opportunity for stroke treatment.
Article
Chemistry, Multidisciplinary
Anurag Chaudhury, Koushik Debnath, Nikhil R. Jana, Jaydeep K. Basu
Summary: The study investigates the interaction between nanoparticles and cell membranes, and identifies key parameters, including charge, crowding, and membrane fluidity, that determine the adsorbed concentration and unbinding transition of nanoparticles.
Article
Chemistry, Multidisciplinary
Sina Sadeghi, Fazel Bateni, Taekhoon Kim, Dae Yong Son, Jeffrey A. Bennett, Negin Orouji, Venkat S. Punati, Christine Stark, Teagan D. Cerra, Rami Awad, Fernando Delgado-Licona, Jinge Xu, Nikolai Mukhin, Hannah Dickerson, Kristofer G. Reyes, Milad Abolhasani
Summary: In this study, an autonomous approach for the development of lead-free metal halide perovskite nanocrystals is presented, which integrates a modular microfluidic platform with machine learning-assisted synthesis modeling. This approach enables rapid and optimized synthesis of copper-based lead-free nanocrystals.
Article
Chemistry, Multidisciplinary
Zahir Abbas, Nissar Hussain, Surender Kumar, Shaikh M. Mobin
Summary: The rational construction of free-standing and flexible electrodes for electrochemical energy storage devices is an emerging research focus. In this study, a redox-active metal-organic framework (MOF) was prepared on carbon nanofibers using an in situ approach, resulting in a flexible electrode with high redox-active behavior and unique properties such as high flexibility and lightweight. The prepared electrode showed excellent cyclic retention and rate capability in supercapacitor applications. Additionally, it could be used as a freestanding electrode in flexible devices at different bending angles.
Article
Chemistry, Multidisciplinary
Lishan Zhang, Xiaoting Zhang, Hui Ran, Ze Chen, Yicheng Ye, Jiamiao Jiang, Ziwei Hu, Miral Azechi, Fei Peng, Hao Tian, Zhili Xu, Yingfeng Tu
Summary: Photodynamic therapy (PDT) is a promising local treatment modality in cancer therapy, but its therapeutic efficacy is restricted by ineffective delivery of photosensitizers and tumor hypoxia. In this study, a phototactic Chlorella-based near-infrared (NIR) driven green affording-oxygen microrobot system was developed for enhanced PDT. The system exhibited desirable phototaxis and continuous oxygen generation, leading to the inhibition of tumor growth in mice. This study demonstrates the potential of using a light-driven green affording-oxygen microrobot to enhance photodynamic therapy.
Article
Chemistry, Multidisciplinary
Yujin Li, Jing Xu, Xinqi Luo, Futing Wang, Zhong Dong, Ke-Jing Huang, Chengjie Hu, Mengyi Hou, Ren Cai
Summary: In this study, hollow heterostructured materials were constructed using an innovative template-engaged method as cathodes for zinc-ion batteries. The materials exhibited fast Zn2+ transport channels, improved electrical conductivity, and controlled volume expansion during cycling. The designed structure allowed for an admirable reversible capacity and high coulombic efficiency.
Article
Chemistry, Multidisciplinary
Paritosh Mahato, Shashi Shekhar, Rahul Yadav, Saptarshi Mukherjee
Summary: This study comprehensively elucidates the role of the core and electrostatic surface of metal nanoclusters in catalytic reduction reactions. The electrostatic surface dramatically modulates the reactivity of metal nanoclusters.
Article
Chemistry, Multidisciplinary
Pei Liu, Mengdi Liang, Zhengwei Liu, Haiyu Long, Han Cheng, Jiahe Su, Zhongbiao Tan, Xuewen He, Min Sun, Xiangqian Li, Shuai He
Summary: This study demonstrates a simple and environmentally-friendly method for the synthesis of zinc oxide nanozymes (ZnO NZs) using wasted hop extract (WHE). The WHE-ZnO NZs exhibit exceptional peroxidase-like activity and serve as effective catalysts for the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2). In addition, a straightforward colorimetric technique for detecting both H2O2 and glucose was developed using the WHE-ZnO NZs as peroxidase-like catalysts.
Article
Chemistry, Multidisciplinary
Hyunkyu Oh, Young Jun Lee, Eun Ji Kim, Jinseok Park, Hee-Eun Kim, Hyunsoo Lee, Hyunjoo Lee, Bumjoon J. Kim
Summary: Mesoporous carbon particles have unique structural properties that make them suitable as support materials for catalytic applications. This study investigates the impact of channel nanostructures on the catalytic activity of porous carbon particles (PCPs) by fabricating PCPs with controlled channel exposure on the carbon surface. The results show that PCPs with highly open channel nanostructures exhibit significantly higher catalytic activity compared to those with closed channel nanostructures.
Article
Chemistry, Multidisciplinary
Yunjie Lu, Zhaohui Li, Zewei Li, Shihao Zhou, Ning Zhang, Jianming Zhang, Lu Zong
Summary: A tough, long-lasting adhesive and highly conductive nanocomposite hydrogel (PACPH) was fabricated via the synergy of interfacial entanglement and adhesion group densification. PACPH possesses excellent mechanical properties, interfacial adhesion strength, and conductivity, making it a promising material for long-term monitoring of human activities and electrocardiogram signals.
Article
Chemistry, Multidisciplinary
Zichao Wei, Audrey Vandergriff, Chung-Hao Liu, Maham Liaqat, Mu-Ping Nieh, Yu Lei, Jie He
Summary: We have developed a simple method to prepare polymer-grafted plasmonic metal nanoparticles with pH-responsive surface-enhanced Raman scattering. By using pH-responsive polymers as ligands, the aggregation of nanoparticles can be controlled, leading to enhanced SERS. The pH-responsive polymer-grafted nanoparticles show high reproducibility and sensitivity in solution, providing a novel approach for SERS without the need for sample pre-concentration.
Article
Chemistry, Multidisciplinary
Melis Ozge Alas Colak, Ahmet Gungor, Merve Buldu Akturk, Emre Erdem, Rukan Genc
Summary: This research investigates the effect of functionalizing carbon dots with hydroxyl polymers on their performance as electrode materials in a supercapacitor. The results show that the functionalized carbon dots exhibit excellent electrochemical performance and improved stability.