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.
Biological minerals represented by calcium carbonate and calcium phosphate are elsewhere in nature. Through different biomineralization processes， they present a wide variety of structures， morphologies， and functions， constituting various tissues and organs. In the field of artificial material synthesis， biomineralized inorganic or inorganic/organic hybrid materials with special structures and biological functions could be obtained by regulating the nucleation and growth of mineral crystal， such as calcium carbonate and calcium phosphate. This article focuses on recent research progresses on the mechanisms and applications of biomimetic mineralization， including crystallization theories （e.g.， classical and non-classical nucleation theories）， crystallization controlling processes （e.g.， using inorganic ions， organic small molecules， biological macromolecules， organic polymers）， biological applications （e.g.， bone tissue engineering， dental enamel restoration， biomimetic enhancement materials， etc.）. At last， we provide a brief outlook on the future research direction of biomimetic mineralization. This article serves as a reference for the preparation and application of advanced bionic materials.
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.
Liquid crystalline elastomers （LCEs） are excellent polymer materials that can respond to external stimuli. By adding various functional materials into LCEs， the composites can respond to various stimuli such as light， electricity and magnetic field， which greatly expand the application range of LCEs. The magnetic response gradually attracts interests due to its characteristics such as remote non-contact control， fast response， good biocompatibility and strong penetrating power. In this paper， the research status and application prospects of magneto-responsive LCEs are discussed.
It is a constant pursuit of chemists to get high-performance polyolefin materials. The structure of the olefin polymerization catalyst plays a crucial role on its catalytic performance. Meanwhile， the defects in polyolefin applications highly depend on their structure modifications， e.g. the toughness of polymer can be increased， the friction coefficient of polymer surface can be reduced or the surface energy can be increased by modification. This review summarizes the research progress of metal olefin polymerization catalysts， including Ziegler-Natta catalysts， metallocene catalysts， non-metallocene catalysts and control strategies. The effects of steric hindrance， bimetallic synergism and fluorine effect of these catalysts are discussed.
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.
Liquid crystals as the basic materials in modern era of information age have been wildly commercially used in displays. Liquid crystal/polymer composites not only have the advantages of anisotropy and stimulus responsive characteristics similar with liquid crystals， but also have the processibility and cost-effectiveness similar with polymers， which have promising applications in building glass and smart car windows. Besides， the interactions between liquid crystals and polymers will affect the molecular alignment of liquid crystals， meanwhile liquid crystals could also affect the formation direction of polymer networks. Thus a lot of interest has been motivated in the study of liquid crystal/polymer composites. Different types of liquid crystal/polymer composites， their characteristics， applications in light-transmittance controllable films and recent advances in reverse-mode films are reviewed. In the framework， we will make emphasis on the summary of the progress in preparation of reverse-mode light-transmittance controllable films based on liquid crystal/polymer composites. Simultaneously， the challenges and applications of reverse-mode film are also discussed and prospected.
Protein is the material basis of all livings， which is the main bearer of life activity and participates in the regulation of physiological functions. Designing proteins with specific functions is of great significance in the fields of protein engineering， biomedicine， and material science. Protein sequence design refers to the design and identification of amino acid sequences that can fold into the desired structure with the desired function. Protein sequence design is the core of rational protein engineering and has great potentials for research and application. With the exponential growth of protein sequence data and the rapid development of deep learning technology， generative models are increasingly used in protein sequence design. This review briefly introduces the significance of protein sequence design and the methods developed for protein sequence design. The principles of the four main generative models used for protein sequence design are discussed in detail. Reports on the latest research and application of generative models in protein sequence representation， generation， and optimization over the past several years are presented. Finally， the future developments of protein sequence design are outlooked.
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.
Liquid phosphorus-31 (31P) nuclear magnetic resonance (NMR) spectroscopy is one of the major analytical technique for the characterization of soil organic phosphorus (Po) species at the molecular level, and usually requires to extract soil Pousing NaOH-EDTA (ethylene diamine tetraacetic acid) solution before the spectrum is collected under high pH (pH=13) conditions. However, soil Pomay be hydrolyzed under high pH conditions, which affects the accuracy of the P-NMR measurements. Furthermore, the pH of soils usually ranges from 6 to 8, and thus it is necessary to explore the differences in the spectra of Pocompounds under different pH conditions. Typical P compounds including D-glucose-6-phosphate disodium (D-G-6-P), 5′-adenosine monophosphate (5′AMP) and sodium dihydrogen phosphate standards were selected for this study under different pH conditions. The results show that the pH change significantly affects spectral features of the investigated Pocompounds. For D-G-6-P, the shape and peak positions of the NMR spectra both change under varied pH conditions, but pH mainly affects the position of 5′AMP and NaH2PO4absorption peaks. D-G-6-P has α-and β-forms in solutions, and transforms into glucose phosphate, mannose phosphate, fructose phosphate and saccharinic acid phosphate, but it mainly exists as 3-hydroxy-2-oxopropyl phosphate and saccharinic acid after degradation, accounting for more than 50% of the total content, at high pH. For 5′-adenosine monophosphate, there are three conformations of 5′AMP in the solution. The resolved peak at high pH probably results from the hydrolysis of 5′AMP to produce orthophosphate, while for NaH2PO4, the existence of and at low and high pH values leads to changes in the peak shift in the spectra. Overall, the extraction of Pousing NaOH-EDTA solution with high pH may significantly change the speciation of Po, and thus induce the changes in their spectra. This study provides theoretical bases for the comprehensive understanding of soil PoNMR spectra and the development of new method to characterize soil Po speciation at pH values approaching natural soil pH ranges.
Holographic polymer/liquid crystal （LC） composites are one type of structure ordered composites with the holographic function， which represent the unique capability of reconstructing the whole infomation of coherent lasers by using the periodically arranged polymer-rich and LC-rich phases. According to LC contents and preparation methods， holographic polymer/LC composites comprised holographic polymer dispersed liquid crystal （HPDLC）， holographic polymer stabilized liquid crystal （HPSLC）， and polymer-liquid-crystal-polymer slices （POLICRYPS）. This review mainly summarizes the methods to tune the structure and performance of HPDLC in recent 5 years， along with the research progress of HPSLC and POLICRYPS. Applications of holographic polymer/LC composites in high-tech fields such as advanced anti-counterfeiting and augmented reality are also highlighted. Last， research challenges and opportunities are proposed.
Liquid crystal elastomer is a kind of cross-linked polymer network in which anisotropic rigid mesogenic units are connected in the polymer network. Its special structure organically combines the elasticity of rubber with the anisotropy of liquid crystal， resulting in special optical and physical properties. Through the modification of 3D printer based on melting deposition technique the accurate ink direct writing technology of liquid crystal elastomer is realized. In this process， the rigid mesogenic units are directly written into the three-dimensional structure with controllable molecular sequence. The arrangement order of mesogens is set by printing path， and different arrangement order can achieve different stimulus response performance. Based on Michael addition reaction， liquid crystal macromolecular precursor ink was prepared and its rheological properties were adjusted so that it could be extruded with a fine needle with a diameter of 0.25 mm， and the printing samples with regular morphology and highly oriented mesogens were obtained by matching with printing parameters. When heated， the aligned single LCE fiber can achieve more than 40% reversible shrinkage along the printing direction. The structure with controlled geometry and stimulus response can achieve thermal deformation and unlimited thermal motion. In addition to the simple thermal deformation behaviors such as bending， bulge， helix， etc.， the printing parameters can be adjusted to achieve flea like jumping， thermal springing and unlimited thermal rolling. This discovery makes 4D printed liquid crystal elastomer samples no longer limited to a simple driver， but a soft robot with intelligent bionic behavior. Through 4D printing mass production software robot can realize intelligent bionics， transportation， exploring unknown environment and other applications.
Hydrogels have tissue-like mechanical properties and excellent biocompatibility， and are widely recognized as ideal candidate materials for bioelectronics. Inspired by bio-tissues such as skin， nerves， and muscles， etc.， a lot of hydrogels with biomimetic structures and functions have been developed to mimic the capability of creatures to sense external stimuli including temperature， pressure， strain， and electric field， etc. Such biomimetic hydrogels have important applications in electronic skin， artificial muscles， and artificial nerves， etc. This article reviews recent progress of biomimetic flexible hydrogel electronics， including representative hydrogel flexible electronic devices， typical applications， and major challenges in this field. Some open key scientific issue and important directions are outlooked in a brief perspective section at the end.
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.