With rapidly growing application of lithium-ion batteries in electric vehicles and renewable energy storage, there is an increasing demand on high performance batteries in terms of energy density and power density. For anode materials, the traditional graphitized carbon materials cannot meet these requirements, novel high-capacity anode materials are being widely investigated, including Si-based materials. Among them, SiO_x is considered to be a promising anode material for the practical use because it can deliver a high capacity and at the same time produce relatively lower volume change upon cycling compared to pure silicon. This paper summarizes the published works on SiO_x-based anode materials. The basic electrochemical performance, structure model, electrochemical reaction mechanism and synthesis methods of SiO_x powders are systematically reviewed. Methods used to improve electrochemical performance are classified and introduced, emphasized on those of SiO and amorphous SiO₂. These works suggested that the oxygen content, disproportionation level and surface state of SiO_x have significant influence on the electrochemical performance of SiO_x. The interface clusters mixture (ICM) structural model can be used to better understand the nature of the electrochemical reaction processes of SiO_x. Introduction of second phase (carbon, metals, metal oxides, etc.), preparation of porous structure, surface modification and optimization of binder and electrolyte are proved to be effective methods to improve the coulombic efficiency and cycling performance of SiO_x electrode. Batteries with optimized SiO_x-based material showed good cycling stability with 90% capacity retention after 600 cycles. SiO_x-based composite is one of the best promising anode materials for lithium-ion batteries with high energy density.

Contents
1 Introduction
2 Properties of SiO_x material
2.1 Basic electrochemical performance
2.2 Structure
2.3 Mechanism of the electrochemical process
2.4 Synthesis methods
3 SiO_x-based materials
3.1 Compositing with second phase
3.2 Porous structured SiO_x
3.3 Surface modification
3.4 Other factors and issues
4 Conclusion and outlook

Silver-containing visible-light photocatalysts including silver-containing non-metal compound, silver-containing multi-metal oxide and other silver-containing composites, have attracted more attention due to their high catalytic activities for oxidation and reduction ability under visible light irradiation. This paper summarizes the research achievements on silver-containing oxides photocatalysts. Silver oxide with a narrow energy gap is a kind of high efficient photocatalysts with photosensitive and unstable properties. In order to overcome the above problems, it is the efficient way to incorporate p/d/s-block non-metal and metal elements to improve photocatalystic activities by hybridizing orbitals. The properties of Ag₂O, Ag₃PO₄, Ag₂CO₃, Ag₆Si₂O₇ and silver-containing multi-metal oxides are introduced in detail. The photocatalystic activities and stability of some composites based on the silver-containing oxides are improved further through forming heterojunction structure and adjusting energy band structure. Finally, some feasible ways to design and improve the visible-light responding photocatalysts are concluded, and the development of silver-containing oxides semiconductor photocatalysts is also proposed.

Contents
1 Introduction
2 The application of silver in the synthesis of photocatalysts
3 Silver oxide and silver oxide based composite
4 Silver-containing non-metal compound/multi-metal oxides and photocatalytic mechanism
4.1 Silver-containing non-metal compound and composite
4.2 Silver-containing multi-metal oxides and composite
5 Other silver-containing composite photocatalysts
6 Conclusion

Ti_nO_2n-1 is a series of substoichiometric oxides of titanium with many excellent properties such as high electronic conductivity, strong visible light absorption, outstanding electrochemistry stability and environmental compatibility. Ti₄O₇ exhibits a single crystal conductivity of 1500 S ·cm^-1, comparable to that of graphite. These materials have been studied for many years and their properties of structure, magnetics and electrics have been widely investigated. A lot of preparation methods have been developed for the purpose of property research and application development. The most commonly used preparation method is reduction of TiO₂ or its precursor at a high temperature, and some interesting morphologies have been obtained, like nanosphere, nanorod and nanowire. In recent years, their wonderful properties arouse peoples interest for their applications in noble electrodes, catalyst carriers, lithium batteries, thermoelectric and photoelectric materials, photocatalysis materials and so on. For example, Ti₄O₇ has been commoditized and utilized in many fields. However, a lot of work is remained to do for the full use of these titanic oxides, such as exploration of new feature and strategies to improve the specific surface area of these materials.According to the work of the predecessors, this paper introduces the structure features, physicochemical properties of Ti_nO_2n-1, and makes a summary of some typical preparation methods and applications, with the purpose of providing some reference for the research and development of Ti_nO_2n-1 series compounds.

Contents
1 Introduction
2 Structural properties of Ti_nO_2n-1
3 Physicochemical properties of Ti_nO_2n-1
4 Preparation methods of Ti_nO_2n-1
4.1 High temperature sintering
4.2 Laser ablation
4.3 Sol-gel sintering
5 Application of Ti_nO_2n-1
5.1 Application of Ti_nO_2n-1 in noble electrodes
5.2 Application of Ti_nO_2n-1 in fuel cells
5.3 Application of Ti_nO_2n-1 in batteries
5.4 Application of Ti_nO_2n-1 in thermoelectric and photoelectric materials
5.5 Application of Ti_nO_2n-1 in photocatalytic degradation
[JP] 6 Conclusion and outlook

Peptides with good biocompatibility and biodegradability, bioactivity and self-assembly ability have received widespread attention. Self-assembly properties of peptides can provide hydrogel formation ability to polymers, and then not only controlling gel network construction but endowing polymer hydrogels with stimuli-responsibility and mechanical modulation properties. By use of peptides with special functionality, chemical crosslinked polymer hydrogels are endowed with cell-adhesive, enzyme-sensitive and antibacterial biofunctionalities. In addition, introducing network construct and structural control properties as well as functionalities of peptide into physical/chemical double crosslinked hydrogels simultaneously can not only turn a hydrogel into functional materials but also enhance the chemical crosslinked network through peptide self-assembly. In this review, we summarize the current achievements in the study of peptide self-assembled polymer hydrogels, peptide-functionalized chemical crosslinked polymer hydrogels and physical/chemical double crosslinked polymer hydrogels based on peptide. Finally, development prospects of such hydrogels are briefly predicted.

Contents
1 Introduction
2 Physical cross-linked hydrogels
2.1 Hydrogels based on coiled coil assembly
2.2 Hydrogels based on β-sheet assembly
2.3 Hydrogels based on triple helix assembly
3 Chemical cross-linked hydrogels
3.1 Cell-adhesive
3.2 Enzyme-degradation
3.3 Antibacterial property
3.4 Tissue-adhesive
4 Physical/chemical double cross-linked hydrogels
5 Conclusion

Since Shirakawa et al discovered that polyacetylene can reach extremely high conductivities, the polymer material has no longer been regarded as electrical insulators. Subsequently, the discovery of polyaniline, polypyrrole, poly(thiophene) expanded the type of conductive polymer. In addition, the conductive polymer has promising application in the fields such as electrode material, solar cell, and other applications, and some of them have achieved the commercialization. Among them, poly(thiophene)s has been widely concerned because of their good stability, easy preparation and good characteristics of photoelectrochemical performance after doping. Thus, in this review, several synthetic methods for poly(thiophene)s and their derivatives are reviewed, including chemical oxidation polymerization, electrochemical synthesis, and so on, especially the newly developed solid state polymerization and acid-assisted polymerization. Their synthesis mechanism, the advantages and disadvantages are also discussed.

Contents
1 Introduction
2 Synthetic methods
2.1 Chemical oxidation polymerization and electrochemical polymerization
2.2 Metal-catalysed polymerization
2.3 Photo-induced polymerization
2.4 Photo-electrochemically polymerization
2.5 Solid state polymerization
2.6 Acid-assisted polymerization
3 Conclusion and outlook

Proton exchange membrane fuel cell has been identified as the most promising power source for portable electronic apparatus and automobile power devices due to its unique advantages, such as high conversion efficiencies, high power density and fast start-ups at room temperature. The proton conducting channels in proton exchange membranes are attracting more and more attention, because they have significant influence on the proton conductivity of proton exchange membranes. The construction of well-aligned proton conducting channels in the membrane can not only achieve higher proton conductivity, but also improve the methanol barrier property, thermal stability and chemical stability of proton exchange membranes. The research progress of the proton conducting channels is reviewed in this paper, and the well-aligned proton conducting channels obtained by controlling the morphology of the membranes and their improvements on the performance of the proton exchange membrane fuel cells are also discussed. The present review attempts to summarize the effects of different types of morphologies and the resulting aligned proton conducting channels on the properties of proton exchange membranes as well as the performance of proton exchange membrane fuel cells. In the end, the outlook for future development of proton conducting channels in proton exchange membranes is also prospected.

Contents
1 Introduction
2 Proton conducting channels in PEM
3 Fabrication of well-aligned proton conducting channels and their effects on the performance of PEMFCs
3.1 Spherical microstructures
3.2 Cylindrical microstructures
3.3 Co-continuous microstructures
3.4 Lamellar microstructures
4 Conclusion

Supercapacitor has been recognized as a very promising new energy storage device due to its high power density and long cycle life. Carbon materials, metal oxides and conductive polymers are three more commonly utilized electrode materials for supercapacitors. The combination of the cycling stability of graphene and high capacity of metal oxide provides the graphene/metal oxide composite superiors performance. Consequently, significant research interest has been directed into the research of the graphene/metal oxide composite. In this paper, we present a review on the research progress of the graphene/metal oxide composite for supercapacitor application in term of the types of metal oxides, grapheme structure and preparation methods. Furthermore, the optimum synthesizing conditions and an outlook of the developing trend for the graphene/metal oxide composite are summarized.

Contents
1 Introduction
2 MnO₂/graphene composites
2.1 Solvothermal (hydrothermal) method
2.2 Electrochemical deposition
2.3 Chemical reaction
2.4 Self-assembly method
3 RuO₂/graphene composites
3.1 Sol-gel method
3.2 Solvothermal (hydrothermal) method
4 NiO/graphene composites
4.1 Chemical precipitation
4.2 Solvothermal (hydrothermal) method
4.3 Other methods
5 Co₃O₄/graphene composites
5.1 Chemical precipitation
5.2 Solvothermal (hydrothermal) method
5.3 Other methods
6 ZnO/graphene composites
7 Other metal oxides
8 Binary metal oxides
9 Conclusion

Lithium-ion batteries are currently the most widely used rechargeable batteries due to the excellent properties. Transition metal nitrides are expected to be used as efficient anode materials for lithium-ion batteries benefiting from their low and flat charging-discharging plateau, good reversibility and high capacity. This paper aims to review the research progress on transition metal nitrides and their composites synthesized by physical and chemical methods for applications of lithium-ion batteries. The key issues existed in transition metal nitrides and the viable route to improve the performance of transition metal nitrides based lithium-ion batteries are also discussed.

Contents
1 Introduction
2 Transition metal nitrides for lithium-ion batteries
2.1 Physical method synthesis of transition metal nitrides
2.2 Chemical method synthesis of transition metal nitrides
2.3 Transition metal nitrides composite materials for lithium-ion batteries
3 Conclusion and outlook

Through over a decade continuous research and development all over the world, the performances of proton exchange membrane fuel cell (PEMFC) for automobile application, such as energy efficiency, power density and specific power of the stack, and the system with low-temperature startup, have achieved breakthrough progress. A new round of fuel cell automobile commercialization now has been approaching. However, the durability of the automobile PEMFC systems, which include massive scale of problems, hasnt met the commercialization target. The durability is the primary problem of vehicle fuel cell commercialization and become the ultimate obstacle of the fuel cell industrialization in the field of automobile application. The problem of durability for automobile PEMFC application has attracted lots of attention worldwide. In this paper, the degradation mechanics of key materials and components in the PEMFC, including catalyst, support material, proton exchange membrane, ionomer in catalyst layer, gas diffusion layer and metal bipolar plate, have been summarized and analyzed in detail. Meanwhile the mitigation strategies for the degradations are also summarized and some novel strategies for durability mitigation are proposed. This paper is instructive for the understanding and promotion of the durability for the PEMFC.

Contents
1 Introduction
2 The degradation of proton exchange membrane fuel cell
2.1 The degradation mechanism of Pt catalyst
2.2 The degradation mechanism of carbon support for catalyst
2.3 The degradation of proton exchange membrane and electrode ionomer
2.4 The degradation of gas diffusion layer
2.5 The degradation of metal bipolar plate
3 The mitigation strategy for degradation
3.1 The mitigation of Pt degradation
3.2 The mitigation of carbon degradation
3.3 The mitigation of proton exchange membrane degradation
3.4 The mitigation of gas diffusion layer degradation
3.5 The mitigation of bipolar plate degradation
4 Conclusion

This review presents current research activities concerning preparation and applications of perovskite-type oxides as electrode materials in the fields of solid-oxide fuel cells (SOFCs) and metal-air batteries. These oxides are synthesized by various methods, including thermal deposition, solid state method, co-precipitation, sol-gel method, hydrothermal method, reverse microemulsion method and template method. These methods result in various morphologies, such as nanaoplates, nanocubes,nanotubes, nanorods, nanofibers and mesoporous structures. The advantage and shortcoming of these methods are summarized, and their characters and proper ranges are listed. As a kind of important functional materials, perovskite-type oxides are extensively used as electrode materials. In the application of SOFCs, the advancement of the perovskite-based electrode materials is reviewed. In order to find a way to satisfy the strict requirements of SOFCs, this article is focused on their phase stability, electronic and/or ionic conductivity, and catalytic activity in different electrodes for SOCFs. The main problems of current perovskite-type oxides as electrode materials for practical application are pointed out and the possible future research directions are proposed. In the application of air electrodes, the parameters influencing catalytic performance and stability for oxygen reduction/evolution are mainly discussed. The possible development trend in investigations and applications of pervoskite-type oxides for electrocatalyst for oxygen reduction/evolution in the future is envisioned.

Contents
1 Introduction
2 Preparation of perovskite-type oxides
2.1 Metal salt deposition
2.2 Solid state method
2.3 Co-precipitation
2.4 Sol-gel method
2.5 Hydrothermal method
2.6 Reverse microemulsion method
2.7 Template methods
3 Applications of perovskite-electrode materials
3.1 Solid oxide fuel cells
3.2 Metal-air batteries
4 Conclusion and outlook

Nitrilase is a crucial enzyme in the field of biocatalysis, which can be used for biosynthesis of various carboxylic acids from corresponding nitriles. This approach is usually employed for preparing pharmaceutical intermediates because of its superior catalytic characteristics including mild reaction conditions, high conversion efficiency, prominent selectivity, and eco-friendly nature. Therefore, the nitrilase-mediated biocatalysis conforms to the development directions of atom economy and green chemistry. It has drawn substantial attention from scholars and entrepreneurs due to its application potential. Several studies have been performed to explore its application in synthesis of several pharmaceutical intermediates and numerous nitrilases have been developed as the industrial catalysts. Whereas, mining and modification of nitrilases are gradually becoming research focuses. Moreover, with the rapid advances of modern molecular biology as well as the advent of the third wave of biocatalysis, gene engineering has become a common approach for constructing recombinant strains. The significant advantages of nitrilase-mediated biocatalysis can be represented in maximum degree through improving the catalytic activity of nitrilase and modifying its catalytic properties, which would lay the foundation for more applications of nitrilases in the future. In this review, the application and development for the synthesis of pharmaceutical intermediates with nitrilase are summarized, as well as unprecedented opportunities and challenges in this field are discussed.

Contents
1 Introduction
2 Research overview of nitrilase
3 Existence range of nitrilase
4 Type of nitrilase catalysts and obtaining manners
4.1 Wild enzyme
4.2 Genetically engineered enzyme
5 The applications in the synthesis of pharmaceutical intermediates
5.1 Picolinic acid
5.2 (R)-Mandelic acid and its derivatives
5.3 Cyanocarboxylic acid
5.4 Pharmaceutical amino acid
5.5 Glycolic acid
6 Conclusion and outlook