Gas phase study of the chemical reactions between heteronuclear oxide clusters and small molecules permits to address the behavior of oxides composed of multiple components in catalytic reactions at a strictly molecular level. In this review, we summarize the recent progress in activation and transformation of small molecules by heteronuclear oxide clusters. The local charge, local spin, and structural effects on the reactivity of important reactive oxygen species are discussed. The novel reaction pathways and reaction mechanisms appearing after doping with noble metals are also presented.

Contents
1 Introduction
2 Reactivity of heteronuclear oxide clusters doping with non-noble metals
2.1 Tune the local charge on atomic oxygen radicals
2.2 Tune the local spin on atomic oxygen radicals
2.3 Tune the reactivity of peroxide ions
3 Reactivity of heteronuclear oxide clusters doping with noble metals
3.1 The promotion role of noble metal atoms
3.2 The dominant role of noble metal atoms
3.3 The single atom catalysis
4 Conclusion and outlook

Separation of photogenerated electron-hole pairs is a key step to enhance the photocatalytic activity of semiconductor photocatalysts. Internal electric filed,as a potential driving force to separation of the carriers,has become one of the research hotspots in photocatalytic field recently.In this paper, the literatures about the enhancement of photocatalytic performance based on the internal electric field are reviewed. To align their potentials (E_f), charge transfer occurs between two different component semiconductor materials. This charge redistribution region is known as the space charge region. After the charge transfer, the accumulation of electrons on the semiconductor surface leads to upward band bending. The internal electric field can be formed due to the redistribution of charges, which may in turn facilitate the separation of electrons and holes for reactions. The upward or downward bending can drive the holes/electrons to run up for an oxidation reaction/a reduction reaction, respectively. Internal electric fields within photocatalysts can arise from ferroelectric phenomena, p-n/polymorph junctions,polar surface terminations,and nonlinear optical material. The internal electric fields within photocatalysts mitigate the effects of recombination and back-reaction, then to increase photochemical reactivity. The strategies for manipulation of internal fields are also discussed for the design of efficient photocatalysts. Finally,we highlight some crucial issues in engineering internal electric fields and provide tentative suggestions for future research on increasing their photocatalytic performance. Especially, the importance of using advanced physical technology and theoretical calculation method to characterize the distribution of internal electric field is emphasized.

Contents
1 Introduction
2 Internal electric fields in ferroelectrics
2.1 Internal electric fields in ferroelectrics and photocatalysis reactions
2.2 Factors impacted on the internal electric fields in ferroelectrics
2.3 The application of organic-inorganic perovskite structures in photocatalysts
3 Internal electric fields from p-n junction
3.1 Polaring process within p-n junction
3.2 Photocatalysts with p-n junction
3.3 Factors impacted on p-n junction
4 Internal electric fields from polymorph junctions
5 Polar surface terminations
5.1 Polar surface, internal electric fields and photocatalysis
5.2 Internal electric fields between crystal faces
6 Internal electric fields within noncentronsymmetric compounds
6.1 Nonlinear optical photocatalysts
6.2 Polaring in the photocatalysts with sillenite structure
7 Conclusion and outlook

Semiconductor photocatalytic technology can be used for decomposition, conservation and mineralization of environmental pollutants, so it is a long-term effective approach to purify environmental pollution. Polymer semiconductor graphitic carbon nitride (g-C₃N₄), a new-type metal-free functional material, possesses distinct electronic structure and chemical property, and has attracted a wide spread attention in clean energy conversation and chemical synthesis using solar power. In recent years, the development of g-C₃N₄ makes further progress of environmental purification research using semiconductor photocatalytic technology. In this review, some important advances using g-C₃N₄ as novel photocatalysts for environmental pollutants treatment have been reviewed, including degradation of aqueous organic pollutant, inactivation of bacteria, removal of atmospheric contaminant, detoxication of heavy metal ion, and reduction or conversation of CO₂. High efficiency and stability can be maintained during photocatalytic reaction process. For further improve the catalytic efficiency of g-C₃N₄, many works for structure optimization have been researched. Taking the utilization in degradation of organic pollutant as examples, the modifications of g-C₃N₄ for photocatalytic performance optimization are summarized, including structure optimization, surface and doping modification, composite semiconductor. The photocatalytic reaction mechanisms of g-C₃N₄ for pollutants degradation and CO₂ reduction are elucidated. In addition, the prospects for the development of g-C₃N₄ based semiconductor materials and application in environment pollutants treatment are also discussed.

Contents
1 Introduction
2 Modification of g-C₃N₄ photocatalysts
2.1 Structure optimization
2.2 Surface modification
2.3 Doping modification
2.4 Composite semiconductor
3 Application of g-C₃N₄ in envrionmental purification
3.1 Degradation of aqueous organic pollutants
3.2 Reduction of heavy metal ions
3.3 Inactivation of bacterial
3.4 Removal of atmospheric pollutants
3.5 Reduction and conservation of CO₂
4 Mechanism study of g-C₃N₄ in degradation of environmental pollutants
5 Conclusion and outlook

Visible light responsive semiconductor photocatalysts have attracted considerable attention due to their capacity of efficient use of sunlight to solve energy and environmental problems. Most of bismuth based photocatalysts have narrow bandgap and can absorb abundant visible light in natural solar spectrum. Moreover,the unique layered structure and deeper valance band of the bismuth based photocatalysts make them to have excellent photocatalytic activity and become the focus of research in photocatalysis field. Carbonaceous materials have been widely studied because of their unique physicochemical properties such as large surface area, high thermal and chemical stability and outstanding electron conductivity. Combining bismuth-based photocatalysts with carbonaceous materials, the synergistic effects between them endow the composites with increased surface adsorption capacity, extended light absorption thresholds, and enhanced separation of photogenerated electron/hole pairs. All of these are beneficial to the improvement of photocatalytic activities. In addition, it is easier to separate and recover the composite photocatalysts for recycling utilization, thereby reducing the cost in practical application. Therefore, bismuth based photocatalysts modified with diverse carbonaceous materials are expected to have promising application in future. In this article, the researches on the type, preparation methods, structure, performance, mechanism of action, and application of these carbonaceous materials modified bismuth photocatalysts have been reviewed in detail. The main problems in design, mechanism research and application are presented, and the future development directions have been suggested.

Contents
1 Introduction
1.1 Bismuth based photocatalysts
1.2 Construction of bismuth based composite photocatalysts
2 Carbon loading bismuth based photocatalysts
2.1 Activated carbon supporter
2.2 Graphene supporter
2.3 Carbon nanotubes supporter
2.4 Fullerence and other nanocarbon supporter
3 Carbon coating bismuth-based photocatalysts
4 Carbon doping bismuth-based photocatalysts
5 Conclusion and outlook

The surface electronic distribution and geometric construction of catalysts can be regulated by confined pore canals, which will affect the activity, selectivity and stability of catalysts. Combined with theoretical calculations and experimental methods, from the perspectives of thermodynamics, kinetics, geometric effect and electron transfer, this review illustrates the differences of the active components of catalysts and the characteristics of reaction molecules in different confined systems, and reveals the influence of confined pore canals on the diffusion, adsorption and reaction of reaction species. It aims to provide a reference for the microstructure design and performance control of catalysts.

Contents
1 Introduction
2 Pore confinement effects on diffusion
3 Pore confinement effects on adsorption
4 Pore confinement effects on catalytic reaction
5 Conclusion

Transition metal dichalcogenides (TMDCs) materials has a great potential for applications in electronics and optoelectronics devices owing to its tuning band gap strongly depending on the thickness. Among the TMDCs materials, monolayer MoS₂, as a direct band gap semiconductor, has fascinating optical, electrical, magnetic, thermal and mechanical properties. 2D MoS₂ is expected to be widely used in photodetectors, photovoltic devices, field effect transistors, memory devices, valley electronics, spintronics, thermoelectrics, micro-nanoelectromechanical devices and systems. At present, chemical vapor deposition (CVD) is the most promising method to synthesize large-area two-dimensional transition metal chalcogenide (such as MoS₂, MoSe₂, WS₂ and WSe₂) atomic layers. Electronic and optoelectronic devices of CVD-made 2D MoS₂ have been extensively investigated. In this review, we summarize extensive chemical vapor deposition methods such as thermal decomposition of (NH₄)₂MoS₄, sulfurization of metal Mo or MoO_3-x thin film, gas-phase synthesis of sulfur-based precursors and direct sulfurization of molybdenum foils. Then, the preparation of different 2D heterostructures has also been introduced. On the basis of preparing the 2D materials, we introduce in detail the research progress of MoS₂-based transistors, photoelectric devices, flexible devices and related heterostructures. Finally, we analyze the research of two-dimensional materials with further applications in semiconductor devices.

Contents
1 Introduction
2 Basic character of 2D molybdenum disulfide
2.1 Crystal structure and band structure
2.2 Optical properties
3 Synthesis of 2D molybdenum disulfide via chemical vapor deposition
3.1 Thermal decomposition of (NH₄)₂MoS₄
3.2 Sulfurization of metal Mo or MoO_3-x thin films
3.3 Gas-phase synthesis of sulfur-based precursors
3.4 Direct sulfurization of molybdenum foils
3.5 Synthesis of 2D layered heterostructures
4 Application of 2D molybdenum disulfide in electric devices
4.1 Field effect transistors based on 2D MoS₂
4.2 Photodetectors based on 2D MoS₂
4.3 Flexible electronic devices
4.4 2D layered heterostructures devices
5 Conclusion

Polymer light-emitting diodes (PLEDs) have drawn tremendous research interest in both academia and industry due to their potential applications in large-area flat panel display and solid-state lighting. With excellent properties of low-cost, lightweight, flexible and large-scale manufacture by using solution processing approaches, such as spin-coating, ink-jet printing and roll-to-roll, PLEDs have gotten more and more attention. Compared with fluorescent PLEDs, which use only singlet excitons for light emission, phosphorescent PLEDs can utilize both singlet and triplet excitons for light emission, which increases the quantum efficiency of PLEDs. Theoretically, the quantum efficiency of phosphorescent PLEDs can be higher than that of fluorescent PLEDs by four times and an external quantum efficiency over 20% can be obtained. Iridium complex-containing phosphorescent materials have been successfully developed and applied in high performance solution-processed PLEDs. Among them, the iridium complexes are covalently bonded into the polymer main chain or onto side chain, which can effectively avoid the phase separation and dopant aggregation. Thus, efficient electrophosphorescent devices based on these materials with reduced efficiency loss could be expected. More recently, solution-processed supramolecular polymers with iridium complexes were also successfully demonstrated and show promising application potential for high performance solution processed PLEDs. Therefore, we review the recent progress of iridium complex-based electrophosphorescent polymers materials in this paper. The synthesis, structural characterization and optoelectronic properties of iridium-based electrophosphorescent materials, including the liner polymers and supramolecular polymers are mainly summarized, and the influence of polymer structure on the material properties is also discussed.

Contents
1 Introduction
2 Electrophosphorescent polymers
2.1 Red electrophosphorescent polymers
2.2 Green electrophosphorescent polymers
2.3 Blue electrophosphorescent polymers
2.4 White electrophosphorescent polymers
3 Electrophosphorescent supramolecular polymers
4 Conclusion

Imidazoledicarboxylate and its 2-position substituted derivatives as a kind of organic ligands with multiple coordination sites, strong coordination abilities and outstanding features of various coordination fashions have been extensively studied and applied in coordination chemistry. Up to now, hundreds of coordination complexes based on imidazoledicarboxylate and its 2-position substituted derivatives with novel topology structures as well as potential applications in numerous areas, have been reported by domestic and foreign researchers. The coordination modes are summarized in the review. The coordinate features, the types of imidazoledicarboxylate derivatives as well as the related coordination polymers, which are classified into two groups according to the different imidazoledicarboxylate 2-position substituted derivatives with alkyl and bulky aromatic groups. Moreover, the synthesis, crystal structures, potential applications such as fluorescence, gas adsorption, magnetic, catalytic and dielectric properties of corresponding polymers are also simply described. Finally, the research prospects of coordination polymers based on imidazoledicarboxylate derivatives are proposed.

Contents
1 Introduction
2 The features of imidazoledicarboxylate coordination
3 The research progress of complexes based on imidazoledicarboxylate
4 The research progress of complexes based on imidazoledicarboxylate derivatives
4.1 Imidazoledicarboxylate derivatives with alkyl groups
4.2 Imidazoledicarboxylate derivatives with aromatic groups
5 Properties
5.1 Fluorescence
5.2 Gas adsorption
5.3 Magnetism
5.4 Catalysis
5.5 Dielectric
6 Outlook

Amides have been one of the most popular compounds in organic chemistry. There are plenty of important applications in many fields such as medicinal chemistry, biochemistry and polymer synthesis. Highly efficient synthesis of amides has become a hot topic in recent years. In this review, the application of transition metal catalysis and small molecule organocatalysis in the synthesis of amides in the last few years is briefly summarized, and the prospects of the synthesis of amides are also discussed.

Contents
1 Introduction
2 Amides synthesis of transition metal
2.1 Synthesis of amides by gold catalysts
2.2 Synthesis of amides by ruthenium-based catalysts
2.3 Synthesis of amides by copper catalysts
2.4 Synthesis of amides by iron and nickel catalysts
2.5 Synthesis of amides by palladium catalysts
3 Synthesis of amides by small molecule organic catalysts
4 Synthesis of amides by other methods
5 Conclusion

Much attention has been paid to the synthesis of 1,3-diynes with the development of its wide applications in the fields of organic synthesis and functional materials. This review describes the synthesis history of the 1,3-diynes and emphatically the synthesis development of 1,3-diynes in recent 10 years. It introduces the new achievements in synthesis of 1,3-diynes from its starting materials including terminal alkynes, alkynyl halides, metal acetylides, alkenyl halides, and other precursors. Medical applications of some reactions and relevant mechanisms are also described in this paper. Finally, the synthesis of 1,3-diynes is concluded and the development trends in the field of 1,3-diynes synthesis are proposed.

Contents
1 Introduction
2 Synthesis from terminal alkynes
2.1 Catalyzed by Pd-Cu
2.2 Catalyzed by Pd
2.3 Catalyzed by Cu
2.4 Other methods from terminal alkynes
3 Synthesis from alkynyl halides
4 Synthesis from metal acetylides
5 Synthesis from alkenyl halides
6 Other methods
7 Conclusion

Water-soluble conjugated polymers (WSCPs) have been widely used in chemical and biological sensing owning to their intriguing optoelectronic and biocompatible properties. However, these linear WSCPs suffer from the general drawbacks of low water-solubility and fluorescence quantum efficiency. Polymer brushes is a kind of unique macromolecules with a linear polymeric backbone and densely grafted side chains. Developing water-soluble conjugated polymer brushes (WSCPBs) is highly anticipated to solve the above mentioned problems. This article reviews the synthetic protocol and structure-properties relationship of WSCPBs to guide the design and preparation of new WSCPBs. In addition, we highlight the applications of WSCPBs in terms of sensor, bioimaging, drug delivery and surfactant. Finally, the future opportunities and challenges of WSCPBs are discussed.

Contents
1 Introduction
2 The synthesis of water-soluble conjugated polymer brushes
2.1 Grafting from approach
2.2 Grafting onto approach
2.3 Grafting through approach
3 Structure-properties relationship of water-soluble conjugated polymer brushes
3.1 Effects of conjugated backbone
3.2 Effects of graft side chains
4 Application of water-soluble conjugated polymer brushes
4.1 Sensor
4.2 Bioimaging
4.3 Drug delivery
4.4 Surfactant
5 Conclusion and outlook

The nanofiltration is a type of pressure-driven membrane separation technology with properties between ultrafiltration and reverse osmosis. It offers several advantages such as low operation pressure, no phase transition, high separation efficiency, relatively low operation and maintenance costs. The application range of nanofiltration membrane in drinking water production, wastewater treatment, chemical processing, pharmaceutical and food industry and other potential beneficiaries has extended tremendously. Therefore, nanofiltration membranes with good separation performances are required for more complicated applications. To address these requirements, positively charged nanofiltration membranes have received more and more attentions. Polyethyleneimine (PEI) which is an important amine groups function cationic polyelectrolyte, has become one of the most important positively nanofiltration membrane materials because of its superior hydrophilicity, high charge density and reactivity. Preparation of positively PEI NF membranes (P-PEI-NFM) with high separation efficiency, good stability, pH stability, solvent resistance, antibacterial and antifouling properties has become a hot spot in recent years. Recent preparation methods of P-PEI-NFM are reviewed in this paper, and the applications such as in water softening, heavy metal removal, separation and concentration of basic dyes, separation of antibiotics and solvent resistant nanofiltration are summarized. The major problems existed at present are pointed out. In addition, this paper also provides useful information about the development of P-PEI-NFM.

Contents
1 Introduction
2 Preparation methods of positively charged polyethyleneimine nanofiltration membranes
2.1 Interfacial polymerization
2.2 Chemical cross-linking
2.3 Layer-by-layer self-assembly
2.4 Surface modification
2.5 Other preparation methods
3 Applications of positively charged polyethyleneimine nanofiltration membranes
[JP] 3.1 Water softening
3.2 Heavy metal removal
3.3 Separation and concentration of basic dyes
3.4 Separation of antibiotics
3.5 Solvent resistant nanofiltration
4 Conclusion and outlook

Molecularly imprinted polymers (MIPs) are a new kind of smart polymers with molecular recognition sites complementary to the template molecules in shape, size and functional groups. MIPs can selectively recognize and effectively concentrate target analytes (template molecules) as well as reduce matrices interferences, and they have been widely applied in many fields such as sample pretreatment, chemical/biological sensors, and drug delivery. However, there are still some problems during the traditional synthesis processes of MIPs, such as incomplete template removal, low binding capacity, slow mass transfer and binding kinetic. Surface imprinting is a very effective way to solve the problems, and the resultant core-shell MIPs have cavities at the polymer surface or close to the surface, which can facilitate the elution and diffusion of the template molecules, and increase effective recognition sites and improve imprinting capacities. This review summarizes several types of core-shell MIPs including magnetic core and non-magnetic core, focusing on their preparation and applications. Also, the preparation and development of hollow core-shell MIPs are discussed. Finally, the future outlook of core-shell MIPs is proposed.

Contents
1 Introduction
2 Core-shell molecularly imprinted polymers
2.1 Magnetic core-shell MIPs
2.2 Non-magnetic core-shell MIPs
3 Hollow core-shell MIPs
4 Conclusion and outlook

Halogenated organic compounds (HOCs) are attributed as one of the major environmental contaminants. Hydrodehalogenation (HDH) has become an effective approach to degrade HOCs. Therefore, exploring various methods of catalytic HDH has persistently attracted many research concerns in this field. Among these methods, due to its special electronic effect and steric effect, metal complexes (MCs) have also presented the efficient catalytic dehalogenation performance. So the catalytic dehalogenation by MCs is reported as the novel HDH method in many recent studies. In this review, the reaction types and mechanisms are summarized for the catalytic dehalogenation processes of fluorinated, chlorinated, and brominated organic compounds using various MCs. It is indicated that the electron transfer conditions, spatial structure, and the affinity of ligand to halogen in HOCs play the major roles to dehalogenation reaction. Additionally, the influential factors including central metal ions, ligands, types of HOCs, reductants, etc. are discussed and analyzed for their effects on catalytic dehalogenation reaction. Finally, it is proposed about existing problems of the catalytic dehalogenation using MCs. Moreover, the future trends for the development of this method to HOCs degradation are prospected.

Contents
1 Introduction
2 Types and mechanisms of catalytic dehalogenation by MCs
2.1 Dechlorination and debromination
2.2 Defluorination
3 Influential factors
3.1 Effect of central ion and ligand in MCs
3.2 Effect of HOCs categories, substituted position of halogen atoms and functional groups
3.3 Effect of reductant
3.4 Effect of solvent
3.5 Effect of pH
3.6 Effect of catalyst support
4 Conclusion and outlook

Flexible batteries have attracted more and more attentions as the key component for the flexible electronic devices. Recently, flexible lithium-ion batteries have been developed quickly and applied to roll-up displays, touch screens, wearable sensors and implantable medical devices. In this review, we mainly focus on recent research of flexible lithium-ion batteries, and summarize how to realize flexibility of each component of the lithium-ion batteries, including current collectors,electrode materials and solid electrolytes. In addition, the structural design strategies for the realization of stretchable character are introduced,which can be divided into Wave-Structural Configuration, Interconnect-Island Mesh Configuration, Textile Structural Configuration, Origami Design Configuration and Cable-Type Configuration according to the different structural features. In order to promote the flexibility of the batteries to a large extent, we propose that the flexible materials should combine with novel stretchable structures. At the same time,we make a brief overview on the latest development for other flexible battery systems, such as lithium-sulfur battery, fuel cell and solar cell. Finally, the existing issues of flexible lithium-ion batteries during their development processes, the forecast the prospects and challenges toward the practical applications of flexible lithium-ion batteries in electronic devices are summarized.

Contents
1 Introduction
2 Flexible lithium batteries
2.1 Collector
2.2 Electrode material
2.3 Flexible solid electrolyte
2.4 Design of stretchable structure
3 Other flexible battery systems
3.1 Li-S flexible batteries
3.2 Flexible system of solar cells and fuel cells
4 Prospect of flexible batteries

The electrochemical anodization method is a simple and versatile process for fabricating well aligned valve-metal oxide nanotube arrays, and the morphology of the nanotube arrays can also be controlled via adjusting the parameters during electrochemical anodization process. Due to their chemical/physical functionality, nanotubes fabricated via electrochemical anodization method have been applied in various fields. The basic formation process of oxide nanotube arrays and three classical models for porous anodic oxide formation are reviewed here. Through the Al, Ti, Zr, which are typical valve-metals, the aim is to illustrate their key processes responsible for the formation of porous anodic oxide film and their general anodic oxidation preparation process. The fabrication methods of other valve-metals even their alloys are reviewed in this paper as well. Furthermore, in combination with the results of the research on Al, Ti, Zr, anodic voltage, electrolyte type, electrolyte concentration, reaction time and so on, which could affect the morphology of the final products, are presented and discussed in detail. The present views may be helpful to adjust the anodization conditions to fabricate well aligned valve-metal oxide nanotube arrays for their extensive applications.

Contents
1 Introduction
2 The basic principle and the common methods of the electrochemical anodization
2.1 The basic principle of the electrochemical anodization
2.2 Preparation of anodic aluminum oxide (AAO)
2.3 Preparation of anodic titanium oxide (ATO)
2.4 Preparation of anodic zirconium oxide (AZO)
3 The essential parameter of electrochemical anodization
3.1 Anodic voltage
3.2 Electrolyte type
3.3 Concentration of the electrolyte
3.4 Reaction time
3.5 Times of anodization
3.6 The metal shape
4 Conclusions