Layered double hydroxides, a class of anionic clays possessing sandwich like structure in which negative anions are sandwiched into positively charged metal layers in a repeating manner, have been studied extensively. Layered double hydroxides could be fabricated with combination of different divalent (Cd2+, Mn2+, Fe2+, Pb2+) and trivalent (Al3+, Cr3+, Fe3+) metals and layered arrangement imparts unique properties such as adsorption properties and catalytic properties in these compounds. Exciting feature of these compounds is the memory effect. There are a number of methods to synthesize these layered compounds, such as co-precipitation, hydrothermal, sol-gel, urea hydrolysis, etc. The synthesized LDHs can be characterized morphologically and compositionally i.e. scanning electron microscopy, transmission electron microscopy, powder X-Ray diffraction, Mossbauer spectroscopy, thermogravimetric analysis, XPS, etc. The wonderful feature of layered double hydroxides is the pliancy of interlayer space enabling them to accommodate various anionic species, and high surface area making them efficient in numerous applications such as adsorbents, anion exchange, catalysts, and biological compatible.
Polybrominated diphenyl ethers (PBDEs) are a group of persistent organic pollutants which have attracted a lot of concern because of their unreasonable use and disposal. Efforts have been paid to developing techniques to rapidly degrade PBDEs, among which the application of zero-valent iron (ZVI) has been found effective because of the reducibility and the ability of activating advanced oxidation processes (AOPs). In this paper, the research on degradation of PBDEs by ZVI are summarized, and the mechanism, kinetics, influencing factors and degradation pathways are reviewed. Although ZVI can be effectively used as direct electron donors for debromination of highly-brominated DEs, the resultant lower brominated DEs are more toxic and generally need further treatment. On the other hand, recent studies indicate ZVI could be used as indirect electron donors by inducing heterogeneous Fenton systems or persulfate (PS) systems to produce reactive oxygen species (ROS), which could degrade lower brominated DEs through ring opening. Therefore, the integration of ZVI and Fenton systems or persulfate systems by constituting two-stage reduction/subsequent oxidation treatment may be a solution for complete ring-opening degradation of highly-brominated DEs. Besides, further research on PBDEs degradation based on ZVI technology is discussed.
Ternary nickel cobalt manganese cathode materials are one of the most important cathode materials of lithium ion batteries. Ni-Co-Mn ternary materials have much higher power density than LiFePO4 and lower cost than LiCoO2, so it is becoming the dominant cathode material for power battery. However, there are still some shortcomings of Ni-Co-Mn ternary materials, such as poor stability and rate performance. In recent years, great efforts have been made to improve the materials through exploring new synthesis method and modifying the materials via doping and coating techniques, and some progress has been achieved. In this paper, the latest progress on the synthesis, doping and coating of Ni-Co-Mn ternary materials are introduced. Furthermore, a perspective for the development tendency of Ni-Co-Mn ternary materials is also made.
The increasing greenhouse gas CO2 emission poses a potential threat to global climate. Electrochemical reduction of CO2 (CO2RR) to useful chemical products, an artificial way of carbon recycling, opens up new possibilities of utilization of CO2 and represents one promising solution that significantly improve the environment and promotes sustainable development. However, it remains a challenge to convert CO2 to valued products with high efficiency and selectivity while suppressing the H-2 evolution (HER) side reaction. Copper attracts considerable attention currently because it displays interesting electrocatalytic performances for the reduction of CO2. Progress related to the electrocatalytic reduction of CO2 in the past few years, and their advantages and disadvantages are reviewed, and thermodynamics and kinetics research of CO2RR is described, with a focus on the progress in CO2RR on copper-based electrodes, which includes Cu electrode, Cu metal organic frameworks electrode and Cu-based electrodes modified by oxidation, alloying, nanocrystalization and surface modification, even if the CO2 electrocatalytic reduction reaction mechanism remains uncertain. Finally, challenges and future research opportunities for tuning the selective conversion of CO2 on copper -based catalysts with high efficiency are also discussed.
Thermoelectric materials are one kind of functional materials, which can realize the direct conversion between electrical energy and thermal energy, and have wide applications in the fields of thermoelectric power generation and refrigeration. Graphene is a two-dimensional carbon material of a single atomic layer with special crystal structure and excellent physical and chemical properties. Many research demonstrate that the excellent electrical performance, large surface and various boundary structures of graphene can optimize the electrical and thermal performance of materials, making graphene of great application potentials in the field of thermoelectrics. In this paper, based on the characteristics of thermoelectric materials and graphene, the relationship of structure and performance of graphene when graphene itself is researched as thermoelectric material is reviewed. The effect of graphene on the microstructure and performances of conventional inorganic thermoelectric materials and conducting polymer thermoelectric materials when graphene is used to form nanocomposites with these thermoelectric materials are also summarized In addition, the exiting problems and further outlook of the applications of graphene in the field of thermoelectric are discussed.
One of the major advantages of organic electronics is the solution processability that enables the fabrications of devices by various printing methods. Screen printing which is known as one of the most well developed printing methods, has been widely applied in the fabrication of electronic devices. This review mainly introduce the composition of screen printing, the tuning factors that could alter the screen printing' s precision and the applications of screen printing in flexible electronic devices, including field-effect transistors, solar cells, and organic light emitting diodes. Finally, the difficulties and challenges of screen printing in printed flexible electronic devices are summurized.
Schiff-base covalent organic frameworks (Schiff-base COFs) are a class of crystalline porous polymers with strong covalent bonds via Schiff-base condensation reaction. The COFs materials possess the advantages of low density, large surface area, tunable pore size and structure, facilely tailored functionality, versatile covalent-combination of building units, diverse synthetic methods, easy of introducing specific molecular recognition sites, excellent physical and chemical stability, and so on. These advantages provide the COFs materials with superior potentials in diverse applications, such as gas storage/adsorption, sensing, catalysis, optoelectronic material, and as enrichment media of sample pretreatment. Currently, Schiff-base COFs have become a research hotspot in the field of materials science. This review mainly describes the state-of-the-art development in the synthesis, preparation and application of Schiff-base COFs materials. In the end, the current statuses of COFs are summarized, and the future trends and application potentials of the COFs materials are also prospected.
Serine octamer as a unique "magic-number" cluster in the gas phase, has been extensively studied by experimentalists and theorists since its discovery in mass spectrometry in 2001. It is characterized by a pronounced preference of homochirality. Interestingly, the chirality of serine octamer can transfer to other molecules through enantioselective substitution reactions. Thus it is suggested that it might be related to the origin of our homochiral world. In this review, all the results and progresses in the formation, structure and chiral signature of serine octamer and substituted serine octamer over the past years are summarized Different methods, including mass spectrometry with different ionization sources, gas phase H/D exchange, ion mobility, infrared photodissociation spectroscopy, and theoretical calculations are applied for the cluster ions. Different characteristics of the magic cluster are discovered gradually, helping us to have a deep insight into its structure and role in chiral recognition and transmission. However, due to the complexity of the system, it is still a big challenge to understand its true structure, the reason of its performance in homochirality and its role in the origin of biomolecular homochirality.
Lignin is a natural phenolic polymer and the second most abundant component next to cellulose in almost all plant biomass. However, only 2% of lignin is applied to industrial production due to the complexity of lignin structure. Therefore, the importance of comprehensive utilization of lignin should be addressed. It is a very important and promising approach for oxidative and reductive depolymerization of lignin polymer into aromatic compounds in lignin valorization. Oxidative depolymerization of lignin can significantly reduce the bond energy of main chemical bonds in lignin, which promotes the conversion of lignin into highly functionalized lignin monomer, such as vanillin, syringaldehyde, homovanillin. The reductive depolymerization can remove the oxygen-containing functional groups of the lignin and facilitate the transformation of lignin into low-oxygen and oxygen-free bio-oil, which can be applied to high caloric value bio-fuel. Besides, condensation reaction is conspicuously suppressed during reductive depolymerization. A brief introduction of the lignin structure unit, connecting and the recent progress in oxidative and reductive depolymerization of lignin are reviewed intensively. In. addition, the catalytic mechanism for the depolymerization of lignin is also discussed. Furthermore, forthcoming research emphasis and directions of lignin depolymerization are proposed at the end of the review based on existing problems in this area.
In this review we give a comprehensive account of a hierarchical equations of motion (HEOM) approach to the characterization of stationary and dynamic properties of open quantum systems. This approach is rooted at the Feynman-Vernon influence functional path integral formalism, but much more implementable numerically and operationally for the study of various complex molecular dynamics and quantum transport in strongly correlated electronic systems. By construction, HEOM resolves nonperturbatively the combined effects of many-particle interaction, system-bath coupling,and non-Markovian memory. Finally the practicality of HEOM to address physical and chemical problems is exemplified with a model simulation of coherent two-dimensional spectroscopy signals of a biological light-harvesting system and a time-dependent quantum transport system involving dynamic Kondo transition.
The up and down conversion technology can convert the infrared and ultraviolet light into the visible light in the range of 300 similar to 800 nm, which can solve the energy loss caused by spectral mismatch, and the absorption spectrum of the cell can be expanded to improve the light utilization and conversion efficiency. The rare earth ion is often used as the center ion of the up and down conversion materials because of the special structure of the energy level and the high luminous efficiency. In recent years, the center ion of up conversion is mainly Er3+, Tm3+ and the sensitization center is Yb3+ with longer excited state lifetime. Tb3+, Eu3+ and Sm3+ have charge transfer absorption band in the ultraviolet region, which can be easily excited by ultraviolet light and the emission spectrum mainly located in the visible region, so they are often used as the center ion of down conversion. The host is usually fluoride and the materials with high crystallinity, small particle size and uniform distribution were prepared by hydrothermal method. At present, the research on up and down conversion applied to DSC is getting more and more important. In this paper, we mainly discuss the application of up and down conversion in DSC, and prospect the future development direction.
Graphite has been used as the negative electrode in lithium ion batteries for more than a decade. But it can't meet the needs of power battery application due to the low specific capacity. To attain higher energy density batteries, tin, which can alloy reversibly with lithium, has been considered as a replacement for graphite. However, tin anodes always suffer from high volume changes during charge/discharge cycling, leading to premature degradation of the anode. Since carbonaceous materials exhibit high electrical conductivity, good mechanical compliance, and stable lithium storage capacities with a small volume expansion, people have paid more attention to them. In order to make full use of the advantages of both tin and carbon, different matrix phases are evaluated for tin-carbon (Sn-C) nanocomposites in this paper. Several carbonaceous materials including amorphous carbon, graphite (G), graphene (GP), carbon nanotubes (CNT), and carbon nanofibers (CNF) have been exploited as an inert and conductive matrix in Sn-based anode materials, thus providing various tin-carbon composite anode materials. After reviewing that, the focus turns to alloys of tin with metal (M) and carbon, forming ternary and multiple composite anode materials. Based on the progress that has already been made on the relationship between the properties and microstructures of Sn-carbon-based anodes, it is believed that manipulating the multi-phase and multi-scale structures could offer important means for further charge/discharge improving the capacity and cyclability of Sn anodes. Overall, the Sn-Co-C-based composite anode materials may open the door to application.
DNA possesses characteristics such as excellent biocompatibility, biodegradation, molecular recognition ability, nanoscale controllability and programmability. In recent decades, DNA has taken on an assortment of diverse roles, not only as the central genetic molecule in biological systems but also as generic materials for nanoscale engineering. DNA hydrogel combines the characteristics both from DNA and hydrogel, such as controllable shape, high mechanical strength, materials delivery. The hydrogel formation includes chemical method based formation via covalent bond and physical method based formation via non covalent bond. DNA hydrogel can combine with perssad, molecule or DNA sequence which can be sensitive to incitant stimulating factor in order to expand the application of DNA hydrogel. DNA hydrogel can be sensitive to stimuli response, such as pH, light, temperature and small molecules. These novel DNA hydrogels provide a natural bridge between nanotechnology and biotechnology, and this also leads DNA hydrogel to far-ranging real-world applications. Because of this, DNA hydrogel as a smart material has been widely used in biosensor, drug delivery, and three-dimensional cell culture. In this review, we summarize the classification of DNA hydrogel and then give the stimuli-response DNA hydrogel and its biological application. Also, the development prospect of DNA hydrogel is demonstrated.
It is known that the active layer morphology of bulk heterojunction organic solar cells has significant impact on the performance of solar cell devices. However, the widely used morphology characterization methods such as transmission electron microscopy (TEM), atomic force microscopy (AFM) have certain limitations in the characterization of organic thin film materials. By using the huge difference of the refractive index of the different materials under the soft X-ray, resonant soft X-ray scattering (R-SoXS) provides highly enhanced contrast, overcomes the drawbacks such as low contrast between/among different organic components and the lack of 3D information, which is important to obtain the phase separation information in the active layer of organic solar cells, to understand the microstructure, and to establish the relationship between the morphology and the photoelectric conversion process. This article provides an overview of the effect of active layer morphology on the performance of bulk heterojunctio
Natural products hold great promises for being developed into chemopreventive drugs due to their low toxicity and high accessibility. However, poor oral bioavailability limits the biological effects of many natural products in vivo. This paper reviews the factors that affect the bioavailability of several classes of important chemopreventive natural products including resveratrol, curcumin, berberine, genistein, quercetin, allium compound, and ginsenoside compound K. The up-to-date research data suggested that membrane permeability, solubility, and metabolism are the primary factors that limit the oral bioavailability of these natural products although chemical and microbial stability may also contribute to the problem. An important direction for future investigation is to further optimize the oral bioavailabilities of these natural products and realize their chemopreventive and chemotherapeutic effects in vivo.
The biosensing technology plays an important role in environmental monitoring, safety control and medical diagnosis. Precise control of the interaction between bio-recognition probe and the interface is critical to improve the sensitivity, specificity and selectivity of biosensors. In a typical bioprobe immobilization, the heterogeneity of self-assembled monolayers on the surface increases the binding energy barrier and decreases the recognition efficiency and rate. We found that DNA nanostructures, such as tetrahedral DNA nanostructures (TDNs), could increase the homogeneity of self-assembled monolayers via enthalpy-entropy compensation, which enables precise regulation of interfacial property at the nanoscale. By regulating the intermolecular distance of bioprobes, the hybridization efficiency and hybridization rate of DNA probes can be improved significantly. The detection limit of DNA and microRNA can be pushed down to 10 aM limit. The detection limit of antigen detection can be improved to 100 pM and the
The combination of supramolecular chemistry with interfaces enhances the development of supramolecular chemistry as well as colloid and interface science. Supramolecular chemistry at interfaces allows for the construction of various smart and soft surfaces that can adapt to environmental changes, such as biomimetic surfaces and self-cleaning surfaces. In this article, we discuss strategies for the transfer of supramolecular complexes of azobenzene and cyclodextrin from solution to surfaces for the fabrication of stimuli-responsive surfaces with novel interfacial functions including tunable surface wettability, reversible protein adsorption and resistance, and photo-switchable bioelectrocatalysis. It is anticipated that these concepts can be extended to other supramolecular systems in order to engineer functional surfaces with designed structures and functions.
Along with the rapid development of micro and nanotechnology, the colloidal particles are taking more and more important roles in biological field as detective probes for disease diagnosis and drug carriers for sustained release and targeted delivery. On one hand, to fulfill the demands of these biological applications, various novel particulate materials with finely tuned surface chemistry and morphology, well defined stimuli responsiveness as well as adjustable substance loading and release properties have been developed in our lab. On the other hand, efforts are made to understand the cellular uptake of particles, and thereby the influence on cell functions, which is mandatory for their biomedical applications. In this mini-account, we systematically summarize our efforts to prepare and functionalize the particulate materials, especially the hollow mierocapsules fabricated by the layer-by-layer (LbL) assembly of oppositely charged polyelectrolytes on colloidal templates, followed by core removal. The influences of physiochemical properties of these colloidal particles on the cellular uptake, intracellular distribution and transportation are then introduced. Their impacts on cytotoxicity and subsequent cell functions, especially on cell mobility and phenotype,. are also discussed.
Compared to the traditional neutral phosphine-ligated transition metal complexes (PTMCs), the ionic phosphine-ligated ones as the ionic salts are composed with the ion-pairs with unusual electronic effect and varied structural configurations. In these ionic PTMCs, not only the coordinating interaction but also the strong electron-withdrawing effect of the positive-charge and the electrostatic interaction between cations and anion are involved which correspond to the unique catalytic performance. In recent decade, the study on the ionic PTMCs has been concerned as a hot topic in coordination chemistry and homogeneous catalysis. In addition, when the ionic PTMCs are used as the catalysts in combination with the room temperature ionic liquids (RTILs, as the Solvents) for catalytic reactions, the advantages such as the available recovery and recyclability of the catalysts, and the avoided catalyst leaching are evidently observed, which endows theses ionic transition metal complexes great potential applications in