Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
17,060
result(s) for
"Bai, Yang"
Sort by:
Evolution and Synthesis of Carbon Dots: From Carbon Dots to Carbonized Polymer Dots
Despite the various synthesis methods to obtain carbon dots (CDs), the bottom‐up methods are still the most widely administrated route to afford large‐scale and low‐cost synthesis. However, as CDs are developed with increasing reports involved in producing many CDs, the structure and property features have changed enormously compared with the first generation of CDs, raising classification concerns. To this end, a new classification of CDs, named carbonized polymer dots (CPDs), is summarized according to the analysis of structure and property features. Here, CPDs are revealed as an emerging class of CDs with distinctive polymer/carbon hybrid structures and properties. Furthermore, deep insights into the effects of synthesis on the structure/property features of CDs are provided. Herein, the synthesis methods of CDs are also summarized in detail, and the effects of synthesis conditions of the bottom‐up methods in terms of the structures and properties of CPDs are discussed and analyzed comprehensively. Insights into formation process and nucleation mechanism of CPDs are also offered. Finally, a perspective of the future development of CDs is proposed with critical insights into facilitating their potential in various application fields. The classification of carbon dots (CDs) is improved and carbonized polymer dots (CPDs) are revealed with distinctive polymer/carbon hybrid structures and properties, as a new classification of CDs. The synthesis methods of CDs and effects of synthesis on the structures and properties of CPDs are discussed. Furthermore, insights are offered into the nucleation mechanism and the future development of CPDs.
Journal Article
Superconductivity in an infinite-layer nickelate
The discovery of unconventional superconductivity in (La,Ba)
2
CuO
4
(ref.
1
) has motivated the study of compounds with similar crystal and electronic structure, with the aim of finding additional superconductors and understanding the origins of copper oxide superconductivity. Isostructural examples include bulk superconducting Sr
2
RuO
4
(ref.
2
) and surface-electron-doped Sr
2
IrO
4
, which exhibits spectroscopic signatures consistent with a superconducting gap
3
,
4
, although a zero-resistance state has not yet been observed. This approach has also led to the theoretical investigation of nickelates
5
,
6
, as well as thin-film heterostructures designed to host superconductivity. One such structure is the LaAlO
3
/LaNiO
3
superlattice
7
–
9
, which has been recently proposed for the creation of an artificially layered nickelate heterostructure with a singly occupied
d
x
2
-
y
2
band. The absence of superconductivity observed in previous related experiments has been attributed, at least in part, to incomplete polarization of the
e
g
orbitals
10
. Here we report the observation of superconductivity in an infinite-layer nickelate that is isostructural to infinite-layer copper oxides
11
–
13
. Using soft-chemistry topotactic reduction
14
–
20
, NdNiO
2
and Nd
0.8
Sr
0.2
NiO
2
single-crystal thin films are synthesized by reducing the perovskite precursor phase. Whereas NdNiO
2
exhibits a resistive upturn at low temperature, measurements of the resistivity, critical current density and magnetic-field response of Nd
0.8
Sr
0.2
NiO
2
indicate a superconducting transition temperature of about 9 to 15 kelvin. Because this compound is a member of a series of reduced layered nickelate crystal structures
21
–
23
, these results suggest the possibility of a family of nickelate superconductors analogous to copper oxides
24
and pnictides
25
.
Superconductivity is demonstrated in an infinite-layer nickelate similar to infinite-layer copper oxides, which is synthesized using soft- chemistry topotactic reduction of the perovskite precursor phase.
Journal Article
Ethanol-derived white emissive carbon dots: the formation process investigation and multi-color/white LEDs preparation
Carbon dots (CDs) have attracted much attention due to their excellent photoelectric properties and potential applications. Although previous studies have shown that almost all organic molecules can be converted into CDs via chemical carbonization, the mechanism of the conversion process remains unclear. The hydrothermal/solvothermal method commonly used to prepare CDs is complicated and leads to the generation of many by-product CDs with similar structures. Considering that the purification of the synthesized by-products is difficult, the process of CDs formation cannot be readily analyzed and understood. Herein, we use ethanol as a carbon source to synthesize white-emitting CDs (W-CDs). Column chromatography separation shows that the synthesized W-CDs are composed of blue-, cyan-, and yellow-emitting CDs that fluoresce at wavelengths corresponding to the three emission centers of W-CDs. Although the samples have similar graphitic structure, they exhibit different surface states due to variations in the degree of oxidation and carbonization. Therefore, the red-shift in their emission peaks is attributed to an increased degree of carbonization in their polymer structure. Theoretical calculations verify the experimental results, and the prepared CDs are successfully used to develop multi-color and white light-emitting diodes (LEDs).
Journal Article
Carbon Dots in Bioimaging, Biosensing and Therapeutics: A Comprehensive Review
Carbon dots (CDs), comprising crystalline graphitized carbon cores and polymer surface groups, are currently attracting a lot of interest in biological fields owing to their fluorescent properties, high photostability, biocompatibility and low toxicity. In addition, the easy preparation and functionalization of CDs stimulate the development of CDs‐based composite materials with specific functions. Presently, the biological applications of CDs are growing at a remarkable speed, justifying the need for up‐to‐date review articles that capture recent progress in this blossoming field. In this review, breakthroughs in the synthesis, modification, optical properties, toxicology and biocatalytic platforms of CDs are described. Further, recent research related to bioimaging, biosensing, drug delivery, antibacterial, anticancer (photothermal therapy, photodynamic therapy and synergistic therapy) and antiviral therapies involving CDs are discussed in detail. Finally, a perspective on the prospects and challenges of CDs in the fields of biomedicine and biotechnology is provided. The development and application of new functional nanomaterials have always been the focus of various research fields. Among them, carbon dots (CDs) are the newest member of the carbon‐based nanomaterials, which has aroused great interest in bioapplications due to its extraordinary optical and biological properties. Therefore, it is important to make a comprehensive summary of its wide bioapplication values.
Journal Article
Rational Design of Multi‐Color‐Emissive Carbon Dots in a Single Reaction System by Hydrothermal
As an emerging building unit, carbon dots (CDs) have been igniting the revolutionaries in the fields of optoelectronics, biomedicine, and bioimaging. However, the difficulty of synthesizing CDs in aqueous solution with full‐spectrum emission severely hinders further investigation of their emission mechanism and their extensive applications in white light emitting diodes (LEDs). Here, the full‐color‐emission CDs with a unique structure consisting of sp3‐hybridized carbon cores with small domains of partially sp2‐hybridized carbon atoms are reported. First‐principle calculations are initially used to predict that the transformation from sp3 to sp2 hybridization redshifts the emission of CDs. Guided by the theoretical predictions, a simple, convenient, and controllable route to hydrothermally prepare CDs in a single reaction system is developed. The prepared CDs have full‐spectrum emission with an unprecedented two‐photon emission across the whole visible color range. These full‐color‐emission CDs can be further nurtured by slight modifications of the reaction conditions (e.g., temperature, pH) to generate the emission color from blue to red. Finally a flexible LEDs with full‐color emission by using epoxy CDs films is developed, indicating that the strategy affords an industry translational potential over traditional fluorophores. A novel multi‐color‐emissive carbon dots (CDs) with two‐photon fluorescence are developed in aqueous solution for the first time by slight modifications of the reaction conditions. Theoretical calculations combined with experiments show that the photoluminescence mechanism of the multi‐color‐emissive CDs is the size change and the conversion of sp3 to sp2 hybridization.
Journal Article
Precursor-dependent structural diversity in luminescent carbonized polymer dots (CPDs): the nomenclature
Carbon dots (CDs) have received immense attention in the last decade because they are easy-to-prepare, nontoxic, and tailorable carbon-based fluorescent nanomaterials. CDs can be categorized into three subgroups based on their morphology and chemical structure: graphene quantum dots (GQDs), carbon quantum dots (CQDs), and carbonized polymer dots (CPDs). The detailed structures of the materials can vary significantly, even within the same category. This property is particularly predominant in chemically synthesized CPDs, as their formation proceeds via the polymerization–carbonization of molecules or polymer precursors. Abundant precursors endow CPDs with versatile structures and properties. A wide variety of carbon nanomaterials can be grouped under the category of CPDs because of their observed diversity. It is important to understand the precursor-dependent structural diversity observed in CPDs. Appropriate nomenclature for all classes and types of CPDs is proposed for the better utilization of these emerging materials.A wide variety of carbon nanomaterials can be grouped under the category of carbonized polymer dots (CPDs) because of their observed structural diversity. Nomenclature is thus proposed for the better identification of various CPDs materials.
Journal Article
Opportunities and Challenges in the Diagnosis and Treatment of Disorders of Consciousness
Disorders of consciousness (DOCs) are a dynamic and challenging field, presenting significant difficulties for clinicians and neurorehabilitation specialists due to the lack of reliable assessment methods and effective intervention strategies [...]
Journal Article
Aggregation and luminescence in carbonized polymer dots
The aggregate luminescence behavior of organic luminescent materials has been studied extensively. As a new kind of luminescent nanomaterials, carbonized polymer dots (CPDs) not only inherit the stability and biocompatibility of carbon materials, but also possess the luminescence tunability, water solubility, and high photoluminescence quantum yield of organic luminescent materials, rendering them a strong candidate for the next generation of light‐emitting materials. Previously, people mainly understood its luminescence from the perspective of carbon materials, but some luminescence mechanisms are still unclear. In this review, we discuss the luminescence mechanism by referring to organic luminescent materials with emphasis on their aggregation behavior. Firstly, three representative aggregate luminescence phenomena of organic luminescent materials are briefly introduced. Chromophores present in CPDs are elaborated to further discuss the potential interactions between them, with emphasis on the role of crosslinked polymer networks. On this basis, some special luminescence phenomena of CPDs in the aggregate state are summarized, and relevant mechanisms are discussed in detail to consolidate relevant statements. An overview of the chromophores and the unique CEE luminescence mechanism in CPDs, with an introduction to the aggregate luminescence (ACQ, AIE, CTE) of organic luminescent materials and a discussion on the luminescence mechanism of some special luminescent phenomena originated from the aggregation of CPDs.
Journal Article