Issn: CN 22-1128/O6
Director:Chinese Academy of Sciences
Host:Changchun Institute of Applied Chemistry, Chinese Academy of Sciences
As the third generation of new concept solar cells， perovskite solar cells have the advantages of high photoelectric conversion efficiency， low-cost and flexible processing. They have been developed rapidly in recent years. Their photoelectric conversion efficiency has increased from 3.8% at the beginning to 25.5% in the near future. They are gradually comparable to silicon cells and have been close to the level of commercial application. At present， the key link to realize the industrial application of perovskite solar cells is battery packaging. It can not only solve the stability problem of perovskite photovoltaic devices， but also meet the requirements of battery safety， environmental protection and prolonging service life. Combined with the development status of perovskite photovoltaic cell packaging materials and packaging technology in recent ten years， this paper introduces the achievements and shortcomings in the field of perovskite cell packaging， and discusses the advantages and disadvantages of the existing packaging technologies， as well as their applicable different device types. Under different temperature and humidity conditions， the effects of different packaging material properties and packaging process conditions on the efficiency and stability of perovskite battery are compared， and three key factors affecting the packaging effect of perovskite battery thin film are summarized： elastic modulus of polymer， water vapor transmittance and processing temperature. The suitable processing temperature， advantages and disadvantages and processing cost of different polymer film packaging materials are compared. It can be seen that with the strong growth of industrial demand for perovskite photovoltaic cells and the deepening of people's research on their packaging materials， it will be an inevitable trend to study new functional polymer packaging materials suitable for large-scale production and photovoltaic building integration.
The methods for synthesizing methanol from methane include indirect method and direct catalytic oxidation method， but the indirect method requires high equipment， and the methane conversion rate and methanol selectivity are not ideal. Direct catalytic oxidation method （DMTM） can produce methanol with high selectivity through a one-step reaction， and has huge application potential. For DMTM， the homogeneous catalytic system usually requires a special reaction medium combined with a precious metal catalyst. Although the reaction efficiency is high， it is corrosive to the reaction equipment， the product is not easy to separate， and the application prospect is poor. Liquid phase-heterogeneous catalysis generally uses H2O2 as the oxidant， Au， Pd， Fe， Cu and other metal elements as the main active component of the catalyst， and·OH is the main oxidation active substance， which can be used at low temperature to realize the activation and oxidation of methane. Therefore， heterogeneous catalytic systems are currently the mainstream of research. Gas phase-heterogeneous catalysis mainly uses O2 and N2O as oxidants. The former is more active， and the latter is more selective for products. In addition， H2O in anaerobic systems can also be directly used as oxygen donors， commonly Cu， Fe， Rh， etc. elements are used as catalysts. Zeolite molecular sieves are the most widely used support， and metal oxides， metal organic frameworks （MOFs） and graphene are also involved. Multi-metal synergistic catalysis has achieved good results. This article mainly summarizes the research on the direct catalytic oxidation of thermally catalyzed methane to methanol in recent years， and prospects for future research directions.
In the application process of commercial lithium-ion battery electrolyte， the electrolyte， lithium salt lithium hexafluorophosphate （LiPF6）， is prone to hydrolysis in presence of trace water， which can lead to the comprehensive electrochemical performance damage of the battery system. Therefore， it is urgent to control the introduction of trace water in the electrolyte body and measures to reduce the influence of lithium salt and trace water reaction products on the battery system. This article mainly summarizes the characteristics of additives containing different function groups in removing trace amounts of water and acid from electrolytes， and analyzes the function of acid-removing and water-removing. Finally， future research directions as well as application prospects of acid-removing and water-removing additives are prospected.
Graphene quantum dots （GODs） are a kind of novel carbon-based zero-dimensional materials， which can be regarded as extremely small graphene fragments. GQDs possess unique 2D structure， quantum confinement effect and edge effect， which is similar to graphene materials. GQDs have many advantages， such as unique photoluminescence property， low toxicity， high fluorescent stability and high biocompatibility， which result in extensive applications of GQDs， including detection， sensing， catalysis， cellular-imaging， drug delivery and pollution control. The synthesis methods of GQDs could be divided into top-down and bottom-up. The mechanism of the top-down method is cutting large-size materials like graphene， graphite and carbon materials into smaller sizes to obtain GQDs， while the mechanism of the bottom-up method is synthesizing GQDs using different precursors through the hydrothermal method or pyrolysis. Citric acid （CA） is a kind of the most popular precursors used in synthesis of GQDs through the bottom-up method. In the recent years， lots of research related to synthesis of GQDs by using CA as precursors are published. In this study， many CA-based synthesis methods of heterogeneous GQDs and their applications are introduced.
DNA denaturation by thermal melting is critical for DNA amplification and detection. However， the uneven heat distribution and temperature change hinders its application in DNA amplification and detection. It's highly desired to explore a fast and efficient approach to regulating DNA degeneration. In this paper， we propose to apply acid， instead of thermal melting， to accelerate the DNA denaturation by regulating DNA conformation quickly and precisely via protonation of cytosine. We find that the thermodynamic properties of DNA highly depend on its molecular conformation. Furthermore， compared with traditional thermal method， pH method significantly increases the rate of DNA denaturation by more than 6 times. We further found that the mechanism of the pH control method to improve DNA denaturation by rapidly decreasing the enthalpy of double-stranded DNA （160 kJ/mol）， and hope that this method can be used in applications of DNA amplification and detection.
With the technological development and progresses of the semiconductor industry， chip manufacturing is stepping forward to the advanced technology nodes under the impetus of Moore's Law. Meanwhile， the corresponding advanced materials for lithography are highly desired to satisfy the rapid development of advanced lithographic patterning. This review focuses on the composition and performances of materials for lithography. The photoresist from ultraviolet， deep ultraviolet， and extreme ultraviolet light as well as semiconducting photoresist and materials for directed self-assembly （DSA） are systematically summarized. Subsequently， the current market development and requirement of materials for lithography are critically examined. Finally， after a brief summary， an outlook for the prospective studies on advanced materials for lithography and the corresponding solutions to improve the domestic market occupancy is provided.
Metal-organic frameworks （MOFs） as a kind of inorganic-organic hybrid materials have potential applications in many fields due to their diverse structures and unique functionalities. In particular， liquid phase epitaxial layered MOFs films （called SURMOFs films， SURMOFs） have attracted much attention due to their controllable thickness， optimal growth orientation and uniform surface. This article summarizes the liquid phase epitaxy （LPE） layers of assembly MOFs thin film technology and methods， such as layer-by-layer （LBL） dipping method， LBL pump method， layer spray method and LBL spin coating method. The article also introduces the classical SURMOF layers of HKUST-1 assembly strategy and its related applications in photoluminescence， photochromic， photocatalytic and electrocatalysis. As one of the classical MOF materials， HKUST-1 has a wide range of applications in photoelectric field， and it has the unique properties： it can be used as a luminous carrier to achieve good optical properties； it has the advantage of unique Cu catalytic active site and can effectively degrade pollutants； it has potential applications in electronic devices because of its dielectric properties. Since SURMOF HKUST-1 has unique properties in many fields， it also faces some challenges： it needs to simplify the process of film synthesis； the structure of thin films and the mechanism of electrocatalysis also need further study； methods for reducing HKUST-1 internal resistance which can increase the conductivity also need to be improved. SURMOFs still has a long way to go for large-scale industrial applications and expansion to other unexplored areas.
This paper firstly briefly explains the development opportunities of hydrogen energy from three aspects of energy resources， CO2 emission reduction and large-scale energy storage. Subsequently， some challenges faced by the development of hydrogen energy are introduced， and they are also the bottleneck of hydrogen energy development. If these problems are not solved， it is difficult for hydrogen energy to be industrialized. Therefore， focusing on hydrogen production， storage and transportation， infrastructure， key equipment， safety and other fields， this paper introduces the research status and the latest trends in the world， further explains some specific problems and technologies， and gives some directions and technical indicators. In addition， some diversified suggestions for the application of hydrogen energy are also put forward and can be used as a reference for industrial development.
Lithium-sulfur （Li-S） batteries are one of the promising next-generation energy storage technologies due to their high theoretical specific capacity and energy density. However， in practical applications， low conductivity of sulfur and lithium sulfide， dissolution of polysulfides （LIPSs）， and poor conversion of LIPSs to Li2S2/Li2S result in the short lifespan and low rate performance of Li-S batteries. Recent studies show that single-atoms （SAs） with superior catalytic activities are ideal anchoring centers and catalytic sites for LIPSs. Modification of cathodes and separators with SAs helps to adsorb polysulfide， improve reaction kinetics and inhibit the shuttle effect. In addition， introduction of SAs into the anode can significantly improve the reversibility of Li deposition/stripping and inhibit the growth of dendrites. In this paper， we review the research progress of SAs in lithium-sulfur batteries， including material synthesis， characterization methods， application direction and catalytic mechanism. Finally， the key challenges and future developmental trends of SAs are summarized and discussed.
Selective hydrogenation has very important applications in the chemical industry such as synthesis of functional materials and purification of chemical products. In recent years， in order to reduce the impact of the greenhouse effect， the selective hydrogenation of CO2 into other valuable chemicals has become a research hotspot. Among them， the thermal catalysis is widely used， easy to obtain a variety of target products and high yield of products. At present， the heterogeneous thermal catalytic hydrogenation of CO2 to produce methane， methanol， light olefins and other high-value fuels and chemicals has made some progresses， but their development is still challenging. The preparation of high-efficiency catalysts is one of the keys. For a long time， researchers have been committed to solving the problem of catalyst activity and selectivity， and modifying the catalysts by doping with additives and adding functional carriers. In response to these problems， this article briefly introduces the background of the catalytic hydrogenation of CO2 and reviews the catalysts used in the heterogeneous thermal catalytic hydrogenation of CO2 into methane， methanol and light olefin products in recent five years. It is expected to provide a reference for the development of new catalysts in the heterogeneous catalytic hydrogenation of CO2.
Electrolyzing water to hydrogen supported by renewable energy is pivotal for achieving the goal of carbon neutrality and the development of a sustainable society in the future. However， catalytic materials often undergo complex structural evolution during the service process of electrolyzing water， which poses a great challenge to in-depth understand the reaction mechanism of the process of electrolyzing water and precise design of high-efficiency catalytic materials. The real-time monitoring of the dynamic evolution process of the catalytic material structure through in situ electrochemical Raman characterization technology is the key to reveal the dynamic structure-activity correlation of the electrolyzed water material as well as the mechanism of the catalytic reaction. This review introduces the basic principles of in situ electrochemical Raman characterization technology， focusing on the latest developments in the phase structure evolution of catalytic materials， surface active sites and the behavior of interfacial water molecules， and considers the change law between the structure and performance evolution for electrolytic water catalytic materials in service， which provides a technical basis for the accurate construction of dynamic structure-activity correlation in the full life cycle of catalytic materials. Lastly， the problems and challenges of in situ electrochemical Raman characterization technology in the application toward electrolytic water are analyzed and summarized， prospecting the future development of advanced in situ electrochemical Raman technology.
The mechanism for the fluctuation of the retention time of acetic acid dissolved in dimethyl sulfoxide （DMSO） was explored through gas chromatography， infrared spectroscopy， and quantum chemical calculations. Our results indicate that the change in retention time of acetic acid is linearly related to the increase of the volume of DMSO （R2=0.99301）. Infrared spectroscopy analysis shows that a hydrogen bond is formed between DMSO and acetic acid， which passes through the column in the form of DMSO-acetic acid molecules. According to the calculation results of the Gaussian09 program， the high electron density portion of DMSO gives electrons and forms a hydrogen bond with acetic acid， while the portion with the low electron density can easily obtain electrons and form bonds with polyethylene glycol， a column stationary phase with a strong dipole moment， and then adsorb on the fixed liquid. Therefore， under the combined influence of this series of complex intermolecular forces， the retention time of acetic acid fluctuates， and the retention time of acetic acid increases together with the volume ratio of the DMSO solvent.
The rapid development of sustainable energy has made green and clean hydrogen energy a hot spot. Proton exchange membrane （PEM） water electrolysis is a promising technology that can efficiently produce high-purity hydrogen. IrO2， the-state-of-the-art electrocatalyst for the oxygen evolution reaction （OER）， can not only overcome the high corrosion conditions in acidic media， but also exhibit superior catalytic performance. However， due to the scarcity and high price of Ir， it is crucial to develop low-Ir catalysts and improve the OER activity. The study of its reaction mechanism is one of the current research hotspots， and it is also the key to the design of excellent OER catalysts. The conventional adsorbate evolution mechanism （AEM） and lattice oxygen evolution reaction mechanism （LOER） are introduced. Subsequently， based on the two proposed mechanisms， the basic design principles of OER catalysts are introduced， namely， regulating the electronic structure of Ir-based catalysts， improving the adsorption energy of reaction intermediate species on the catalytic active sites， thereby increasing the catalytic activity of OER. It also briefly summarizes the recent research progress of OER catalysts from the three aspects of catalyst structure design， morphology control， and support materials， and the recent research progress of OER catalysts is briefly summarized. Moreover， several unresolved problems are put forward on the basis of the existing OER catalysts， which points out the direction for further research.
All-solid-state lithium-ion batteries possess excellent safety performance and high energy density， and are expected to be the next generation energy storage devices to replace traditional liquid batteries. Solid-state electrolytes are definitely the key materials to achieve the real all-solid-state batteries. In recent years， considerable progress has been made in halide electrolytes， especially rare earth-containing bromide based solid electrolytes （RE-BSEs）， which show good ionic conductivities （up to mS/cm order of magnitude）， electrochemical stability （1.5~3.4 V vs.Li+/Li） and so on. In this article， we review the research advances focusing on the possible applications and technical bottlenecks of RE-BSEs. Hopefully， it may be enlightening and spark some inspirations in terms of synthetic strategies， lithium ion transportation mechanism， and investigating methodologies in the study of RE-BSEs. Rare earth is one of the most important strategic resources of China and even for the world. The research and important achievements made on RE-BSEs show the high value potentials of rare earth elements， especially in fields of solid ionics and energy saving and conversions. It is of great significance for structural adjustment of energy economics， and will contribute to the emission peak and carbon neutrality.
Compared with single lithium or sodium， lithium-sodium alloy has better performance. In-situ electrochemical preparation of lithium sodium alloy is successfully achieved in button battery which is charged and discharged under gradient current density by using sodium metal as the positive electrode， lithium metal as the negative electrode， and LiPF6， NaClO4 or lithium sodium mixed ion electrolyte as the electrolyte. Benefiting from the synergistic effect of lithium and sodium double electrochemically active ions， the lithium-sodium mixed ion capacitors with different lithium contents as negative electrodes show good electrochemical performance. In particular， with lithium sodium alloy with high lithium content as the negative electrode and NaClO4 electrolyte added， Carbon derived from sodium citrate （Sodium citrate derived carbon， SCDC-activated） maintains the high specific capacity of 238 mA·h/g and the capacity retention rate of 99% at the current density of 1 A/g for 300 cycles. With the addition of lithium-sodium mixed ion electrolyte， SCDC-activated exhibits the specific capacity of 319 mA·h/g， and it can retain 93 mA·h/g and 98% capacity retention rate after 1040 cycles.
As a substitute for inorganic glass， organic optical resin has the advantages of light mass， good impact resistance， easy processing， and strong adjustability. The refractive index is one of the main parameters of optical resins. The level of refractive index can directly affect the thickness， aesthetics and comfort of the finished lens. Improving the refractive index of optical resins without reducing the overall performance of optical resins has always been a hot and difficult point in this field. The introduction of sulfur with high molar refractive index into optical resins is considered to be one of the most effective and commonly used methods. In this paper， sulfur-containing optical resins are divided into olefins， epoxys， episulfides， sulfur heterocyclic rings， and polyurethanes. The research progress in recent years at home and abroad is briefly reviewed， involving monomer synthesis， monomer polymerization， and the influences of monomer structures on the comprehensive performances of optical resins. The properties and development of the above materials are also analyzed.
Heavy metals are difficult to biodegrade and pose a serious threat to the environment and human life and health. Hence， the detection and treatment of heavy metal pollution is vital. In recent years， electrochemical methods for the detection of heavy metal ions have become a research hotspot in the field of heavy metal detection because of their high sensitivity， fast analysis speed and the ability to detect multiple metal ions simultaneously. This paper reviews the detection principles and development status of common electrochemical detection methods， and describes the detection effects of potentiometric analysis， potentiometric stripping analysis and voltammetry by introducing the parameters of linear range， detection limit and recovery. Finally， the review outlines the advantages and disadvantages of various methods， and points out the future research directions in order to provide a basis for the application of electrochemical sensors.
As one of the most abundant natural resources on earth， seawater has unique advantages in realizing large-scale hydrogen production from electrochemical water splitting. However， the catalysts at the cathode could be corroded， poisoned or degraded by Cl－， Ca2+ and Mg2+ in seawater， resulting in a significant reduction in their activity and stability. Therefore， the development of cheap， efficient and stable electrocatalysts for hydrogen evolution reaction （HER） on the cathode has attracted intense attention. This review firstly elaborates the major advantages and challenges for hydrogen production from seawater electrolysis. Afterwards， the research progress on transition metal-based HER catalysts for seawater electrolysis， such as selenides， sulfides， phosphates， nitrides and so on， is summarized and discussed. Finally， the future perspectives in the design of efficient and stable HER catalysts for seawater electrolysis are summarized and put forward.
Electrocatalytic reduction of CO2 can directly convert CO2 and water into carbonous products by renewable electric energy under ambient conditions， which has a promising application prospect. However， its application is still limited by the sluggish cathode reaction. It is well-known that the size of the catalyst has a great influence on its activity. Reducing the metal catalyst to nanoscale particles can significantly increase the number of exposed active sites and its intrinsic activity， thus improve its catalytic performance. Furthermore， when the size of the catalyst is reduced to the level of single atom dispersion， the activity of the catalyst can be significantly improved. In recent years， single atom catalysts have become research hotspot in the field of electrocatalytic CO2 reduction owing to their unique geometrical structures and electrical states. In this review， we summarize and review the research on the single atom catalysts towards electrocatalytic reduction of CO2， and also analyze and discuss the difficulties and further research directions in the future.
Covalent organic frameworks （COFs） are a class of emerging materials connected by covalent bonds， which have high thermal/chemical stability （except boric acid COFs）， permanent porosity， large specific surface area and good crystallinity. In addition， the structure of the monomer unit in COFs is adjustable and can coordinate with many transition metal ions to provide catalytic active sites. These advantages make COFs helpful to catalyze various reactions. Among them， COFs have an excellent catalytic effect on the CO2 reduction reaction （CO2RR）. This is mainly because the adjustable pore structure of COFs allows them to adsorb a large amount of CO2 and the π-π stacking structure in COFs can promote charge transfer， which can greatly improve the efficiency of CO2 reduction. COFs can be used as photo/electrocatalysts to efficiently reduce CO2 to CO， CH4， HCOOH and other products. This review discusses the important achievements of CO2RR catalyzed by COFs， including photo/electrocatalytic CO2RR and photoelectric coupling CO2RR. In addition， the future development of COFs as CO2RR catalysts is also prospected.
The greenhouse effect caused by the continuous increase of carbon dioxide concentration has caused a series of ecological and environmental problems such as extreme weather and melting of glaciers around the world. In order to reduce carbon dioxide content and improve the adverse impact of climate warming， it is urgent to develop efficient， green and safe processing technologies and promote the sustainable development of carbon resource cycle. Molten salt ionic liquid， as a good electrochemical conversion medium， provides a promising technical route for carbon dioxide reduction. The research on the capture and electrochemical reduction of carbon dioxide in high-temperature molten salt at home and abroad in recent years is reviewed， and the electrochemical and thermodynamic mechanisms of molten salt electrodeposited carbon are briefly described. The preparation of high value-added carbon materials with different morphologies： amorphous carbon， carbon spheres and carbon nanotubes are summarized， and finally the future development direction is prospected.
Zeolite molecular sieves are indispensable catalysts in many industrial processes. Among them， Beta zeolite has become one of the most widely produced zeolite materials with industrial significance because of its three-dimensional macroporous structure. Compared with the traditional Beta zeolite， the hierarchical Beta zeolite has many advantages such as smaller steric hindrance， higher mass transfer efficiency and so on， which can reduce the formation of carbon deposition， prolong the service time of catalyst and improve the utilization efficiency of catalyst. This review introduces the synthesis of hierarchical Beta zeolite in detail from the two strategies of “bottom-up” （direct synthesis） and “top-down” （post modification）. The synthesis of hierarchical Beta zeolite by hard template method， soft template method， mesoporous template method， dealuminization method and desilication method are introduced， and the characteristics of hierarchical Beta zeolite are briefly introduced. The advantages and problems of various synthesis methods are summarized and the future development prospects are also prospected.
In proton exchange membrane fuel cells， cost， performance and durability are important issues that are need to be resolved before commercialization. The main reason for fuel cell performance degradation during operation is the loss of electrochemical surface area during long-term aging or transient. These losses mainly come from the degradation of the catalyst metal and the corrosion of the carbon support. This is a continuous and irreversible process that will greatly shorten the service life of the fuel cell. In order to explore this problem， 20% （mass fraction） Pt/C catalyst is prepared based on carbon carrier etched by sulfuric acid. The morphology characterization test shows that it is uniformly dispersed and uniform in particle size， which is considered as an excellent material for long-term oxygen reduction （ORR） stability test. Next， the ORR stability test method with different cyclic voltammetry （CV） cycles is used to observe its performance degradation， and a series of physical characterizations， e.g. transmission electron microscopy （TEM）， high-resolution electron microscopy （HRTEM）， X-ray photoelectron spectroscopy （XPS） and Raman spectroscopy （Raman）， are used to further intuitively analyzed the attenuation mechanism. It is reported that the reasons for the degradation of the stability of Pt/C catalysts are mainly from the dissolution， agglomeration， oxidation and migration of Pt particles and the corrosion of carbon supports. This study elucidates the source of the impact on the stability of fuel cells during operation， and provides a reference for designing high-stability commercial ORR catalysts.
Zeolitic imidazolate frameworks?8 （ZIF?8） is a kind of porous material with large specific surface area and strong stability， which is widely used in gas storage， separation， catalysis and other fields. In this work， the effect of different reaction conditions， such as the molar ratio of Zn2+ to 2?methylimidazole， the amount of surfactant and the reaction solvents， on the size and morphology of ZIF?8 were reported. Among these conditions， the molar ratio of Zn2+ to 2?methylimidazole is the key factor affecting the size and morphology of ZIF?8. The synthesized ZIF?8 nanoparticles were characterized by SEM， BET and XRD. The size of ZIF?8 decreases gradually from 1500 nm to 850 nm then to 250 nm， and the morphology changes from truncated hexahedron to truncated dodecahedron and finally to dodecahedron. The specific surface area of ZIF?8 nanoparticles with a particle size of 250 nm is 1730 m2/g， and the pore size and pore volume are 1.5 nm and 0.6 cm3/g， respectively. Therefore， it can be seen that ZIF?8 nanoparticles with a particle size of 250 nm have excellent carrier characteristics. The impregnation method was further adopted to synthesize the supported catalyst， and boron ammonia was used as the reducing agent. The ZIF?8 （250 nm）nanoparticles were loaded with metals/precious metal nanoparticles in situ， the component optimization and catalytic performance were further studied. The obtained catalyst ZIF?8/Pt0.002@Ni0.2 shows excellent performance in hydrogen generation from aminoborane.
Carbon quantum dots （CQDs） are a category of semiconductor-like nano-materials with small particle sizes， significant photo properties and outstanding charge transportation properties， and have been extensively utilized in the modulation and amelioration for the photovoltaic performance of perovskite solar cells （PSCs）. Herein， on the basis of syntheses， properties and applications of CQDs， this paper mainly reviews the recent progress on the utilization of CQDs in the electron transportation layer （ETL）， perovskite light absorbent layer， hole transportation layer （HTL） of PSCs. Finally， the future development trend of perovskite solar device performance modulation with these CQDs materials is also prospected.
Photocatalytic nano-TiO2 is favored for its excellent photocatalysis， chemical stability and broad-spectrum antibacterial properties. However， some problems， such as wide gap， high overpotential and fast recombination of photocarriers， limit its photocatalytic performance. This paper reviews the recent progress of TiO2 photocatalysis in antibacterial research. The mechanism of photocatalytic antibacterial activity of nano-TiO2 is discussed， and several strategies to improve the photocatalytic antibacterial activity of nano-TiO2 are discussed， including the structural design of nano-TiO2， the regulation of light， the doping of metal ions， the doping of non-metal ions， the modification of precious metals and the coupling of other materials. The modified TiO2 photocatalyst inhibits the growth of bacterial cells significantly， which has a unique application prospect in biomedical engineering.
Recently， the use of computational methods such as Molecular Dynamics （MD） simulations and Hansen Solubility Parameters （HSPs） to study the behavior of small molecule gelators has attracted much attention. MD simulation is a computational method based on classical mechanics and is one of the preferred techniques for understanding the process of small molecule gelators. The MD simulation can more accurately analyze the gelation trend or assembly behavior of small molecule gelators， dynamically and graphically display the self-assembly process， effectively reveal the relationship between the structure of small molecule gelators and related gelation behavior， and quantitatively analyze non-covalent bond interactions such as hydrogen bonds， π-π stacking， van der Waals interactions， ionic bonding and solvophobic interactions. By performing molecular dynamics simulations on known gelators/non-gelators， parameters related to gelation behavior in the simulated data are extracted， and the linear correlation is measured by fitting the Pearson correlation coefficient to finally predict the gelation behavior of a certain class of small molecules. On the other hand， the empirical model developed according to the HSPs is the most representative， which consists of the energy of dispersion interaction （δd）， the energy of polar interaction （δp） and H-bonding energy （δh） between molecules. These three parts determine the coordinate point of the three-dimensional space （Hansen space）. According to the range of the point， it can be determined whether the organic small molecule can form a gel in a specific solvent. In this paper， representative works published recently in the field of organic small molecule gels by using MD simulations and empirical models are reviewed. Some comments on the assembly behavior of gelators， the regulation and prediction of non-covalent bond interactions on gelation ability are made.
Posaconazole， as the second generation of triazole antifungal drugs， has a wide antifungal spectrum and strong antibacterial activity. It is widely used in clinical practice. However， it has been eight years since its publication before it is approved in China. In order to better understand posaconazole， a first-line drug with great clinical demand， this paper summarizes the pharmacokinetics， pharmacological properties， clinical application and synthetic route of posaconazole in the literature at home and abroad. It is hoped that it can fill the gap in the domestic API market， break the current situation that the API is completely dependent on import， and provide a useful reference for the industrial R & D.
Alloying is able to adjust physical and chemical properties of noble metal-based nanocatalysts， thus significantly improving their electrocatalytic performance. Although alloying has made many achievements in the past two decades， it still needs in-depth research and understanding to make full use of the advantages of nano-alloys. In this study， we reported a one-step solution-phase synthesis method to co-alloy metalloid boron （B） in palladium-based mesoporous nanocatalysts and further demonstrated their high electrochemical methanol oxidation reaction （MOR） performance in alkaline media. The best PdCuB mesoporous nanocatalyst shows excellent electrochemical MOR activity （2.48 A mgPd-1） and stability. The catalytic mechanism studies shows that B atom not only changes the electronic structure of Pd sites which directly weakens the adsorption strength of CO-based intermediates but also promotes the adsorption of OH－ which optimizes the oxidation of CO-based intermediates （the rete-determining step）. Such a synergy remarkably improves the MOR kinetics and enhances its catalytic performance accordingly. Meanwhile， interstitially inserting metallic B atoms and structural mesoporosity also inhibites the physical Ostwald ripening process and thus stabilizes the catalyst.
Photocatalysis has shown a great potential as a low-cost， environmentally friendly and sustainable treatment technology. However， limitations in incident light utilization and charge separation are major drawbacks that restrict the activity of current semiconductors. Coinage metal nanoclusters have been increasingly explored recently as photocatalytic material due to ultra-small size （<2 nm）， separated energy level and tunable electronic structures. Meanwhile， it is an ideal model for exploring the photocatalytic mechanism at the atomic level because of its atomically precise structure. This review provides an overview of photocatalytic reactions based on coinage metal nanoclusters， including water splitting for hydrogen production， organic pollutant degradation， and aerobic oxidation of amines to imines. By discussing strategies to tailor the photocatalytic properties of coinage metal nanoclusters， the development potential of coinage metal nanocluster photocatalysts are prospected.
The natural plant fiber has a large molecular weight and complex structure and composition， and its thermal cracking products and the composition distribution are also more complex. The fast pyrolysis-comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry （Py-GC×GC-TOF/MS）， thermogravimetry-Fourier transform infrared spectroscopy （TG-FT-IR）， and in situ Fourier transform infrared spectroscopy （in situ FT-IR） methods were used to study the thermal pyrolysis process of six different natural fibers. The distribution of thermal pyrolysis products of different fibers under different pyrolysis temperatures was investigated and the product form was fully discussed. The research results show that the products of fiber pyrolysis mainly include alcohols， aldehydes， ketones， acids， esters， hydrocarbons， dehydrated sugars and CO2， etc. The types of pyrolysis products of different natural plant fibers are obviously different， and the main product types obtained are all different. At the same time， the results of in situ infrared spectroscopy and mass spectrometry show that pyrolysis products are closely related to the pyrolysis temperature. The results of in situ infrared experiments show that when the pyrolysis temperature is lower than 100 ℃， the adsorbed water on the surface of the fiber structure is desorbed， but the fiber structure does not change significantly. When the pyrolysis temperature range is 100~200 ℃， the temperature has little effect toward the pyrolysis process. When the temperature exceeds 300 ℃， the fiber pyrolysis reaction intensifies and the surface structure changes significantly， and the main products are aldehydes and ketones.
Lead， as a heavy metal， is widely used in industrial production， which has a significant impact on the environment and human health. The development of lead ion detection strategies is necessary in recent research areas. Compared with traditional detection methods， the fluorescence method has the advantages of high sensitivity and good selectivity. Therefore， the fluorescence method is often used for qualitative or quantitative analysis of heavy metal ions in actual samples such as water bodies. This review summarizes the research progress on fluorescence detection of lead ions， including fluorescent dyes， fluorescent nanomaterials and fluorescent biomaterials even fluorescent proteins. In addition， an outlook of future development trends and challenges of fluorescence detection is also prospected.
In this paper， the effects of three different anodic materials （copper wire， galvanized steel and nickel wire） on the structure and morphology of carbon materials prepared by electrochemical reduction of CO2 in molten salt were studied. Three carbon structures， e.g.， hollow quadrilateral carbon （HQC，the product with Cu as an anode）， carbon nanosheet （CNS， the product with galvanized steel as an anode） and sponge porous carbon （SPC， the product with Ni as an anode）， were prepared， and their electrocatalytic properties towards the two-electron oxygen reduction reaction （2e- ORR） were explored. The results show that the CNS prepared by using galvanized steel as the anode material is composed of a large number of carbon nanosheets， in which there are abundant pore structure defects. Compared with HQC and SPC， CNS shows the highest 2e- ORR electrocatalytic activity and H2O2 selectivity （close to 90%）. The high activity and selectivity of CNS are attributed to its high ID/IG （ID/IG is the ratio of the intensity of D peak and G peak in Raman spectrum， and its ratio reflects the defective degree of the material） value and high C—O/CO ratio， indicating that structural defects and C—O/CO functional groups are crucial to the catalytic performance of CNS. In addition， CNS exhibits excellent electrocatalytic stability， and the ring current almost does not decay after 14 hours potentiostatic test. The use of CO2 as the carbon source to synthesize electrocatalytic carbon materials not only can be used as a potential option to mitigate the greenhouse effect， but also provide a new idea for the practical application of CO2 derived carbons.
The oxygen reduction reaction is the core electrochemical process for energy storage. Because of its slow kinetic rate， it is urgent to prepare electrocatalysts with high activity to promote the rate of this reaction. The π-π stacking structure of two-dimensional covalent organic frameworks （2D COFs） can endow the framework with high conductivity， and the one-dimensional ordered pores are beneficial to promote the transport of intermediate reactants. Therefore， it has good application prospects in the field of renewable energy and serves as a powerful catalytic platform for energy storage and conversion. Herein， we successfully prepare two 2D COFs （JUC-600 and JUC-601） by introducing metalloporphyrin and thioethers units into 2D COFs. The results suggest that two COFs have AA stacked sql topology. Electrochemical tests show that the Co2+ coordinated JUC-601 has a higher starting potential （0.825 V） and half-wave potential （0.7 V）， a larger active surface area （7.8 mF/cm2）， and a lower Tafel slope （58 mV/dec）. We believe that this is due to the high specific surface area and high porosity of JUC-601， which makes the intermediate products easier to contact and transport on the surface and pores of COFs. In addition， the presence of Co2+-porphyrin units and thioether units changes the electronic structure of the entire skeleton， which is more conducive to electron transfer. This work not only develops new 2D porphyrin-thioether-based COF materials， but also expands the application of COFs in the field of electrocatalysis.
Electrochemical biosensors have made rapid development in the field of wearable healthcare monitoring and have great potential applications in clinical detection due to high sensitivity， good portability， fast response and easy integration. However， non-specific adsorption of non-target biological substances on the electrode surface （i.e.， biofouling） when exposed to the actual clinical biological sample affects the performance of electrochemical biosensors. Therefore， the construction of a sensing interface with antifouling capability （antifouling interface） to prevent non-target substances from adsorbing to the electrode surface is of great importance for expanding the practical application range of electrochemical sensors and realizing detection in complex biological samples. In this review， antifouling electrode interfaces based on physical， chemical， or biological strategies and their application in clinical biomarker detection are summarized， which provides technical references for the improvement of electrochemical biosensors in practical application. Finally， we discuss the principle， current problems and positive prospects of antifouling strategies in complex sample matrix.
Some short peptides can spontaneously self-assemble into various nanostructures via the synergistic driving forces of non-covalent interactions. These non-covalent interactions， including electrostatic interaction， hydrogen bonding， aromatic interactions and other non-covalent interactions， are usually highly coupled together. Through rational sequence design and proper modification of short peptide molecules， the driving forces could be regulated purposively， and the nanostructures and morphologies of the self-assemblies could be controlled accordingly， and thus so as to achieve the fabrication of peptide-based supramolecular biomaterials and develop their functions. In this paper， the effects of hydrogen bonding， π-π stacking， electrostatic interaction， hydrophobic interaction， metal ion coordination and chiral center on the self-assembly behavior of peptide self-assembly have been reviewed. The driving force regulation strategies， including sequence design， pH and concentration adjustment and metal ion coordination， and the resulted nanostructures have also been discussed. We also make the outlooks on the development of peptide-based supramolecular biomaterials with specific functions in biomedicines and biocatalysis.
As the outermost organ of human body， skin is easily injured. Therefore， it is more important to construct protected barrier material for skin. Herein， based on the performance requirement of skin barrier material， we construct a multifunctional skin barrier material PSI-PVA by combining hydrophilically modified polysiloxane （PSI） and polyvinyl alcohol （PVA） through ionic crosslinking. The test results indicate that PSI-PVA exhibits good stretchability in dry and wet and has compatible mechanical properties like skin. PSI-PVA is hydrophilic and the swelling ratio is up to 149% with the PVA content of 20%， and water can volatilize rapidly at room temperature， which makes PSI-PVA good breathability. PSI-PVA has good cleaning performance and can be easily cleaned from skin with water. In addition， PSI-PVA covalently linked with UV-absorbing group of hydroxybenzophenone can effectively decrease UV transmittance. The in vitro experiment indicates that NIH 3T3 cells have high survival rate （71%） irradiated by UVB （311 nm） with the protection of the PSI-PVA film. Furthermore， PSI-PVA also exhibits good biocompatibility through cell viability assay. The skin barrier material PSI-PVA constructed with composite of polysiloxane and polyvinyl alcohol can meet properties requirements and has good application prospects in fields of skin protection and injury repair.
As an emerging material， multifunctional metal-organic framework MIL-88A（Fe） poses a potential application in water treatment. Considering the unique physical and chemical properties of MIL-88A（Fe） （i.e. porous structure， unsaturated metal sites and excellent visible light absorption ability）， MIL-88A（Fe） can heterogeneously combine with other functional materials （i.e. carbon materials， inorganic semiconductor materials） to improve its adsorption and catalytic performance. This paper reviews the application of MIL-88A（Fe） and its composites as adsorbents and catalysts in water treatment. The mechanism of adsorption removal of pollutants in water by MIL-88A（Fe） and its composites （especially heavy metal ions） is summarized， and the reaction mechanism for degradation of organic pollutants in water by MIL-88A（Fe） and its composites in photocatalytic technology， Fenton-like technology， peroxydisulfate advanced oxidation technology and ozone-catalytic technology is introduced. It is pointed out that the MIL-88A（Fe）-based functional materials have problems such as narrow applicable pH range and difficulty in recycling in the process of wastewater treatment. Future research needs to optimize the preparation condition of MIL-88A（Fe） to improve the yield and ensure the regular morphology， small size and high crystallinity of MIL-88A（Fe）， improve the stability of MIL-88A（Fe） by surface coating technology， and enhance the recycling performance of MIL-88A（Fe） by endowing its magnetic property. In addition， according to the structure of the target organic pollutants and water quality condition， it is necessary to reasonably adjust the degradation contribution of the free radical pathway and the non-radical pathway to the target pollutant in the MIL-88A（Fe）-based advanced oxidation process， thus achieving the best decontamination effect.
Layered transition metal oxide cathode materials for sodium-ion batteries have the characteristics of low price and high specific capacity， which is an important support for energy transition in the future and has great development potential. In the process of charging and discharging， the typical layered oxide cathode materials with the most promising development and application will produce a series of changes affecting their electrochemical properties with the insertion and extration of sodium-ion. Therefore， the modification of cathode materials is particularly important. The current mainstream failure mechanism， modification methods， challenges and key problems to be solved in the future development are summarized and put forward.