Metal-organic frameworks (MOFs) are porous crystal materials formed by the self-assembling between organic ligands and metal ions (clusters). With the advantages of high specific surface areas, low densities, adjustable pore structures and easy modification, they have been used in the research fields of separation, catalysis, sensing and drug delivery. MOFs are often isolated as tiny powders, and this form is not suitable for industrial applications due to operating problems, such as dirtiness, mass loss, and difficulties in recycling. To address this issue, several composite materials containing MOFs have been developed with various shaping methods. In this review, we discuss the preparation methods to shape MOFs into beads, thin films and membranes, as well as their potential industrial applications. This paper could provide a reference for developing novel methods for shaping of MOFs and techniques to fabricate large-scale MOF composites.

Contents

1 Introduction

2 MOF beads

2.1 Beads prepared by MOF powders

2.2 MOFs growth in beads

3 MOF films

3.1 Films prepared by MOF powders

3.2 MOFs growth on films

4 MOF mixed?matrix membranes

4.1 Membranes prepared by MOF powders

4.2 MOFs growth in membranes

5 Conclusion and outlook

Metal coordination polyurethanes (MCP) are the aggregates of metal-polyurethane complexes that form between a zero-dimensional metal ion or ionic cluster center with the surrounding array of one-dimension ligand polyurethanes (PU). Those metal-polyurethane complexes exhibit interesting physical characteristics, including thermoplasticity, elasticity, electrical conductivity, fluorescence, etc. The coordination interactions between metal ions and PU lead to formation of supramolecular aggregates, which endow the PU with advanced functionalities at high structural hierarchies across disciplinary boundaries such as self-repair, memory, antibacterial, luminescent, and so on. The orthogonal metal-polymer self-assembly is an ongoing theme in coordination chemistry, and thus brings MCP widely attention from various research areas in recent years. However, there has been not yet a review on this related topic of MCP. Herein, this review summarizes the ways and methods of the interaction between PU and metals from the molecular compositions and structures, and provides a comprehensive discussion on the coordination structures, as well as the related properties and applications. Finally, the prospective on the future development and application of MCP is presented.

Contents

1 Introduction

2 Alkali earth metal coordination polyurethanes

3 Transition metal coordination polyurethanes

4 Rare earth metal coordination polyurethanes

5 Other metal coordination polyurethanes

6 Conclusion and outlook

Xylene is a toxic volatile organic compound (VOC) and one of the common industrial pollutants. Catalytic oxidation can decompose xylene into CO₂ and H₂O, effectively preventing harmful gases from being emitted into the atmosphere. The key to the removal of xylene by catalytic oxidation is the low temperature activity and reaction stability of the catalyst. This article introduces the research progress in low-temperature oxidation of xylene with effects of supported noble metal catalysts, non-noble metal oxides and perovskite-type oxide catalysts from the aspects of catalyst preparation methods, structure-activity relationship, interaction between active components and the interaction mechanism with the supports on the catalytic performance. In addition, the catalytic effects on xylene and other VOCs of different catalyst types are compared and analyzed. Finally, the research results of mixed VOCs containing xylene are introduced and suggestions are made on the related issues of future catalyst research.

Contents

1 Introduction

2 Supported noble metal catalyst

2.1 Catalysts with inert carriers

2.2 Catalysts with active carriers

2.3 Catalysts with zeolite carriers

3 Metal oxide catalyst

3.1 Manganese-based catalysts

3.2 Cerium-based catalysts

3.3 Cobalt-based catalysts

3.4 Mixed-metal catalysts

3.5 Perovskite catalysts

4 Catalytic oxidation of VOCs mixtures containing xylene

5 Conclusion and outlook

Hydrogen energy is an efficient and clean secondary energy that plays an irreplaceable role in realizing "carbon neutral". With the continuous expansion of hydrogen production scale and the reduction in hydrogen production cost, hydrogen energy will become a competitive alternative energy, which can further promote the transformation of China’s energy structure, reduce carbon emissions, and improve China’s energy security and resilience. China is the world’s largest producer of hydrogen, and there are three main industrial hydrogen production routes in China: fossil fuel reforming, industrial by-product hydrogen and the electrolysis of water. Other new hydrogen production technologies, such as hydrogen production from solar photolysis, hydrogen production from biomass, hydrogen production from thermochemical circulation, etc., have attracted extensive attention and investigations. In addition, hydrogen production system is complex, which is difficult for modeling and optimization. Accordingly, artificial intelligence (AI) shows unique advantages in the prediction, evaluation and optimization for hydrogen production system, which is promising and attractive. Based on the recent progress, this article summarizes several critical hydrogen production technologies into four main categories, and further proposes some perspectives for the future development of hydrogen supply structure in China. Finally, this article also reviewes the latest application of artificial intelligence in hydrogen production system to provide new insights for the development of hydrogen production technology in China.

Contents

1 Introduction

2 Hydrogen production from conventional fossil fuel reforming

2.1 Hydrogen production from coal

2.2 Hydrogen production from natural gas

3 Industrial by-product hydrogen

3.1 Pressure swing adsorption

3.2 Low temperature separation

3.3 Membrane separation

3.4 Metal hydride separation

4 Hydrogen production from water electrolysis of clean energy

4.1 AEC

4.2 PEMEC

4.3 SOEC

5 Hydrogen production from other new technologies

5.1 Hydrogen production from solar photolysis of water

5.2 Hydrogen production from biomass fermentation

5.3 Hydrogen production from thermochemical conversion of biomass

5.4 Hydrogen production from thermochemical cycle

6 Comparison of different hydrogen production methods

7 Application of artificial intelligence in hydrogen production system

8 Conclusion and outlook

Formaldehyde (HCHO), as a primary pollutant in indoor air, has attracted much attention due to its wide sources, long release period and carcinogenic characteristics. Due to its high catalytic activity at low temperature, low toxicity and low-cost, MnO₂ has been employed in catalytic decomposition of HCHO. Herein, the research progress of catalytic decomposition of HCHO by MnO₂ is reviewed from three aspects: MnO₂ supported noble metals, structural regulation of MnO₂, and composite of MnO₂ with other non-noble metal materials. The effects of structural regulation strategies such as supported noble metals, crystal structure and morphology, interlayer/tunnel cations, surface defects, atom doping and other composite materials on the catalytic performance of MnO₂ for HCHO were discussed. Moreover, the differences of HCHO catalytic decomposition mechanism between noble metal and non-noble metal are compared. Ultimately, the problems and challenges faced by the purification of the indoor HCHO are analyzed and the research directions for the decomposition of HCHO by MnO₂ are also proposed.

Contents:

1 Introduction

2 Structure and properties of manganese dioxides

3 Research progress on catalytic decomposition of HCHO by manganese dioxides

3.1 Catalytic decomposition of HCHO by manganese dioxide supported noble metals

3.2 Catalytic decomposition of HCHO by non?noble metal manganese dioxides

4 Mechanism of catalytic decomposition

4.1 Catalytic decomposition mechanism of HCHO by noble metals

4.2 Catalytic decomposition mechanism of HCHO by manganese dioxides

5 Conclusion and outlook

Tumor hypoxia is associated with tumor proliferation, differentiation, angiogenesis and energy metabolism. It has been found that hypoxia induces chemoresistance and poor prognosis in varieties of solid tumors. Hypoxia-inducible factor 1 (HIF-1) is an important transcription factor and regulator for inducing cells to adapt to hypoxia or anoxia environment. By regulating the expression of downstream targets such as EPO, VEGF, and GLUT, HIF-1 has been implicated in the activation of tumor glycolysis, angiogenesis and metastasis. Therefore, the discovery and development of small molecule inhibitors targeting HIF-1 may potentially lead to new chemotherapy for cancer treatment. In this review, we summarize the current state of the art and recent progress in the development of HIF-1 small molecule inhibitors, which may provide new insights into the design and discovery of HIF-1 targeted innovational drugs.

Contents

1 Introduction

2 Tumor hypoxia-inducible factor signaling pathway

2.1 Oxygen dependent regulation of HIF-1

2.2 Oxygen independent regulation of HIF-1

3 Antitumor small molecule inhibitors targeting HIF-1

3.1 Decreased HIF-1α mRNA expression

3.2 Decreased HIF-1α protein expression

3.3 Increased HIF-1α protein degradation

3.4 Decreased HIF heterodimerization

3.5 Decreased HIF DNA binding

3.6 Decreased HIF-1 transcriptional activity

4 Outlook

Lithium batteries have been widely used. However, traditional liquid electrolyte applied in the cell bring about unsatisfactory growth of lithium dendrite and safety problems due to its leak and low boiling point. Gel polymer electrolytes (GPEs) are intermediate substance between liquid electrolyte and solid electrolyte, which can act as not only electrolyte, but also battery separator, which reduce leakage risk of liquid electrolytes and high interface resistance of solid electrolytes. In the review, the preparation methods of different types of GPEs in lithium batteries, such as solution casting, phase conversion, in-situ polymerization, UV(ultraviolet) curing and electrospinning methods are concluded, and the applications of different fibers-based GPEs (poly (vinylidenefluoride, PVDF), poly (vinylidene fluoride-co-hexafluoropropene, PVDF-HFP), polymethyl methacrylate (PMMA), poly acrylonitrile (PAN) and poly-m-phenyleneisophthalamide (PMIA)) in lithium batteries are emphatically summarized. Finally, we conclude with an outlook section to provide some insights on the future prospects of GPEs in lithium batteries. The discussion and proposed strategies in the review will offer more avenues to the practical application of lithium batteries with high electrochemical performance in the future.

Contents

1 Introduction

2 Preparation methods of GPEs

2.1 Solution casting method

2.2 Phase inversion method

2.3 In?situ polymerization technology

2.4 UV curing technology

2.5 Electrospining method

3 GPEs in lithium ion batteries

3.1 GPEs based on PVDF

3.2 GPEs based on PVDF?HFP

3.3 GPEs based on PMMA

3.4 GPEs based on PAN

3.5 GPEs based on PMIA

3.6 Others

4 Conclusion and outlook

MOF-74 with high-density exposed metal sites, adjustable one-dimensional pores, and high thermal stability, has attracted extensive attention and in-depth exploration of scientific researchers. This review summarizes the development of MOF-74 from the following three parts: 1) mainly focusing on the structures and assembly strategies of MOF-74 and its isomers including solvothermal method, normal temperature method, microwave assisted method, Dry-Gel method, etc. In addition, the effects of reaction solvents, auxiliary ligands, regulators and other factors on the target compound are also discussed; 2) Considering the synergy effects among the materials, the development status of MOF-74-based composite materials is also summarized, including the construction types of materials and typical synthesis methods; 3) The special properties of MOF-74 such as porosity, Lewis acid-base sites, structural stability, and the excellent performance of the composite material are further discussed in detail, which allow the MOF-74 framework material to find wide applications in the fields of catalysis, separation, detection, adsorption, and energy storage. Finally, a reasonable idea for the construction of the new MOF-74 isomers has been discussed.

Contents

1 Introduction

2 Synthesis of MOF?74?based materials

2.1 Synthesis of MOF?74 materials

2.2 Synthesis of MOF?74 isomer materials

2.3 Synthesis of MOF?74 composite materials

3 Application of MOF?74 materials

3.1 Gas adsorption and separation

3.2 Catalysis

3.3 Battery and capacitor

3.4 Chemical sensing

4 Conclusion and outlook

In recent years, paper-based biosensors have attracted increasing attention due to their low cost, ease of operation and disposal, biodegradability and low consumption of analytes. Among them, the paper-based fluorescent biosensors with functional nucleic acids as the recognition elements are of particular attraction. Their high sensitivity, instant response and real-time detection capabilities endow them with great potentials for applications in portable sensor devices. In addition, the paper-based cell-free protein synthesis platform, using nucleic acid as the recognition elements, can achieve specific detection of viruses, heavy metals and other targets by expressing the fluorescent proteins as the output reporter, which has good application prospects. Here we introduce the design of these fluorogenic nucleic acid-based paper biosensors, focusing on the integration methods of nucleic acid-based recognition elements and paper-based substrates. We also discuss the latest progress of their applications in different fields including clinical diagnosis, food contaminant detection and environmental pollutant detection as well as their advantages and limitations. Finally, the prospects and development directions of fluorogenic nucleic acid-based paper biosensors are presented, providing reference for research in related fields.

Contents

1 Introduction

2 Design

2.1 Physical adsorption

2.2 Covalent coupling

2.3 Entrapment immobilization

3 Applications

3.1 Clinical diagnosis

3.2 Food safety detection

3.3 Environmental pollutant detection

4 Conclusions and outlook

Mass spectrometry is an analytical technique that has been extensively used in the areas of chemistry, biomedicine, pharmacology, environment, agriculture and energy. It is based on the detection of accurate mass-to-charge ratios of molecular ions and fragment ions for the structural identification of diverse biological molecules. How to efficiently ionize and dissociate neutral molecules present in various samples and generate positive or negative ions are the key to the instrumentation of mass spectrometry and the development of enabling analytical methods. There are various ionization and dissociation techniques based on different physical chemical mechanisms that have unique advantages suitable for specific analytical goals. Most soft ionization techniques generate ions with even-numbered electrons that are very stable and need the coupling to other dissociation techniques for further molecular fragmentation. Besides those techniques based on collision activation and electron gains/losses, photo irradiation based techniques can provide wavelength/energy adjustable photons to initiate specific cleavages of chemical bonds. This work is aimed to review fundamental principles and instrumentations of infrared and ultraviolet photo-induced ionization and dissociation. The application to the analysis of different biological molecules including small organic molecules, proteins, nucleic acids, lipids and carbohydrates are also addressed.

Contents

1 Introduction

2 Overview of ionization techniques in mass spectrometry

2.1 Electron impact/electron capture ionization

2.2 Electrospray ionization and matrix assisted ionization

2.3 Surface ionization

2.4 Atomic/ionic beam ionization

3 Overview of dissociation techniques in mass spectrometry

4 Fundamental principles of photo ionization/dissociation

4.1 Direct photo ionization and dissociation

4.2 Coupling of photo dissociation with other ionization techniques

5 Instrumentation

5.1 Infrared multiphoton dissociation

5.2 Ultraviolet photo dissociation

6 Structural identification of biomolecules

6.1 Small organic molecules

6.2 Monosaccharides and polysaccharides

6.3 Peptides/proteins

6.4 Nucleic acids

7 Conclusion and prospect

With rapid development of social economy, shortage of energy and destruction of ecology have gradually aroused people’s strong concern. In recent years, finding the suitable solution has become the focus of attention. As a green environmental protection technology, photocatalysis has become a research hotspot to deal with energy and environmental issues because of its high efficiency and low cost. In many photocatalytic materials, ternary sulfide Indium Zinc Sulfide (ZnIn₂S₄) has shown great potential due to visible-light-responding characteristics, simple preparation and excellent stability. However, high carrier recombination rate of the ZnIn₂S₄ limits its photocatalytic activity. In recent years, many studies on modifying ZnIn₂S₄ have been reported. Here, different modification researches are introduced in detail including synthesis of ZnIn₂S₄ monomer, construction of semiconductor compounds, noble metal deposition, carbon element modification, and ion doping. Then, their photocatalytic properties and corresponding mechanisms including hydrogen evolution, degradation of organic pollutants, reduction of hexavalent chromium and CO₂, and organic synthesis are systematically summarized. Finally, development direction and prospect of ZnIn₂S₄ are put forward for more extensive and in-depth research on photocatalytic properties and application in practical production as soon as possible.

Contents

1 Introduction

1.1 Photocatalytic technology

1.2 Preparation of indium zinc sulfide

2 Synthesis and modification of indium zinc sulfide

2.1 Synthesis of indium zinc sulfide monomer

2.2 Semiconductor compounds construction

2.3 Nobel metal deposition

2.4 Carbon element modification

2.5 Ion doping

3 Application of indium zinc sulfide in the field of photocatalysis

3.1 Photocatalytic hydrogen evolution

3.2 Photocatalytic degradation of organic pollutants

3.3 Application of indium zinc sulfide in other fields

3.4 Stability of indium zinc sulfide

4 Conclusion and outlook

A gas sensor working at room temperature shows great potential in practical applications due to its lower energy consumption, good stability, high security and ease of miniaturization. World-wide efforts have been devoted to explore materials with excellent room-temperature gas sensing performance. Metal oxide semiconductor materials are widely sourced, environmentally friendly and flexible in structure control. Research of metal oxide semiconductor based sensors operated at room temperature has made significant progress recently. In this paper, the development process and working principle of metal oxide gas sensors are introduced, various metal oxide nanostructures in regard to their room-temperature gas sensing properties are comprehensively reviewed. Particular emphasis is given to those effective strategies for constructing room-temperature sensors and their sensing mechanism. Finally, some future research perspectives in the field of room-temperature sensors are discussed as well.

Contents

1 Introduction

2 Development process of MOS gas sensors

3 Working principle of MOS gas sensors

4 Construction of nanostructured MOS gas sensors with room?temperature sensing performance

4.1 Pure metal oxide nanostructures

4.2 Metal oxide hetero? or composite?nanostructures

4.3 UV assisted gas sensing material

5 Conclusion and outlook

Superhydrophobic materials have attracted widespread attention due to their unique non-wetting properties, and have been rapidly developed in recent years. Multifunctional superhydrophobic surfaces suitable for different fields have emerged. Among them, transparent superhydrophobic materials are favored by people because of their special contributions in the optical field. The transparent hydrophobic coating technology is of great significance for practical applications. The transparent coating can not only meet the high light transmittance requirement of optical device protection, but also maintain the basic appearance of the protective body, and shows broad application prospects in the fields of self-cleaning, anti-fouling, anti-icing, anti-fog, anti-corrosion, etc. Here, we systematically elaborate the latest developments in the research progress of superhydrophobic surfaces and functional transparent superhydrophobic surfaces, surface design, manufacturing, and their applications. Although many significant progress has been made, the current durability of superhydrophobic materials still have many problems, such as easy to damage by mechanical external force, instability of superhydrophobic properties on the surface under extreme environments, and aging problems, which limits the wide range of applications of transparent hydrophobic coating technology. In future research, on one hand, relevant theoretical knowledge is to be further enriched to provide more theoretical support for the application of transparent hydrophobic coating technology. On the other hand, improving the transparency and mechanical durability of the coating is still the top priority of future research.

Contents

1 Introduction

2 Theoretical basis

2.1 Wettability related theories

2.2 The construction principle of transparent superhydrophobic surface

3 Preparation method of transparent superhydro-phobic surface

3.1 Chemical Vapour Deposition (CVD)

3.2 Dry etching technique

3.3 Colloidal lithography

3.4 Self-assembled film

3.5 Electrochemical method

3.6 Sol-gel method

3.7 Other methods

4 Application

4.1 Self-cleaning

4.2 Field of optics

4.3 Anti-fouling

4.4 Anti-icing and anti-fog

4.5 Anti-corrosion

5 Conclusion and outlook

Marine mussels can quickly and firmly anchor to foreign surfaces in seawater using their byssus and plaque. Mussels produce byssus and plaque through a physiological process similar to “injection production”. Mussels squeeze liquid protein into the ventral groove on their feet, which will then form hair-like byssus in seconds. Each byssus connects with a plaque at its end, and the plaque can firmly adhere to rocks or other solid surfaces. Byssus and plaque are composed of a variety of mussel foot proteins (Mfps), and almost every Mfps contains L-3,4-dihydroxyphenylalanine (DOPA). In the past few decades, researchers have basically revealed the structure of Mfps and their adhesion mechanism. The catechol group of DOPA achieves strong interfacial bonding through a variety of covalent and non-covalent interactions, such as oxidative crosslinking, metal-catechol coordination, hydrogen bonding, electrostatic interaction, hydrophobic interactions, π-π interactions, cation-π interactions, etc. Based on the structure of Mfps and their adhesion mechanism, a variety of new biomimetic DOPA adhesives with excellent mechanical properties and functionalization have been obtained using polymer system modified by DOPA and its analogues. In this review, we first introduce the composition and adhesion mechanism of Mfps, then discuss the corresponding structure characteristics and adhesion mechanism of coacervate adhesives, hydrogels adhesives and intelligent adhesives. Finally, the existing problems and future development prospects of underwater biomimetic adhesives are presented.

Contents

1 Introduction

2 Species and distribution of mussel foot proteins

3 Adhesion mechanism of mussel foot proteins

4 Research progress of underwater biomimetic adhesives

4.1 Coacervate type of underwater adhesives

4.2 Hydrogel type of underwater adhesive

4.3 Smart type of underwater adhesive

4.4 DOPA-free type of underwater adhesives

5 Application prospect of underwater adhesives

5.1 Anti-corrosion and maintenance of ships

5.2 Surgical wound suturing and tissue repair

5.3 Intelligent biomimetic equipment

6 Conclusion and outlook

The over-reliance on fossil fuels leads to deteriorating ecological environment and motivates us to develop sustainable and clean energy alternatives in order for our long-term survival on the earth. Hydrogen energy is one of the most promising energy carriers in the 21^st century since the only by-product is H₂O. In comparison to steam reforming of natural gas and coal, hydrogen evolution reaction (HER) via H₂O electrolysis is a more attracting pathway for H₂ production because of the low cost, high efficiency and abundant raw materials, which would contribute to a lower carbon footprint. HER requires stable and active enough catalyst materials to overcome the reaction barriers. It is well known that Pt group materials are state-of-the-art HER catalysts, but unfortunately, the low abundance and high cost complicate its large-scale applications. The transition metal disulfides (TMDs) possess a two-dimensional layered structure and a larger specific surface area, which is conducive to expose more active sites. In particular, MoS₂, a representative of TMDs, has attracted tremendous research interests in HER domain and is supposed to be a cost-affordable alternative to Pt-based catalysts. In this work, the research status of MoS₂ modified by single atoms (SA-MoS₂) of noble metal, non-noble metal, and nonmetal, to catalyze HER reactions is reviewed. Based on the overpotential and Tafel slope, the structure-function relationship between HER performance and SA-MoS₂ structures is summarized. Finally, future research directions are proposed and hopefully, this paper will guide rational design of SA-MoS₂ for a more efficient HER electrocatalyst.

Contents

1 Introduction

2 Metal single-atom doped MoS₂

2.1 Noble metal elements platinum (Pt), palladium (Pd), ruthenium (Ru), tungsten (W)

2.2 Transition metal elements nickel (Ni), cobalt (Co), copper (Cu)

3 Non-metal single-atom doped MoS₂

4 Conclusion and outlook

Photocatalytic technology has shown great potential for purification of low-concentration nitric oxide (NO) pollution due to its energy-saving property, high efficiency, and limited secondary pollution. Among various semiconductors, bismuth oxyiodide (BiOI) photocatalyst has drawn considerable attention in recent years due to the superior photocatalytic activity and stability, since its narrow band gap and specific layered structure is in favor of visible light absorption and electron-hole pairs separation. Hence, we overview the latest research progress in the photocatalytic purification of NO by BiOI and introduce the influence of crystalline morphology and facets on its photocatalytic performance. The modification and activity enhancement mechanism of BiOI is emphatically expounded, for example, surface modification, ion doping and heterostructure construction. The future prospects and challenges in this research spot are put forward for the sake of providing theoretical reference and technical support for the design of highly active BiOI and the efficient purification of low concentration NO.

Contents

1 Introduction

2 Reaction mechanism and pathway of photocatalytic purification of NO

3 Controlled synthesis of bismuth oxyiodide

3.1 Morphological control

3.2 Crystal plane control

4 Surface modification and ion doping of bismuth oxyiodide

5 Construction of bismuth oxyiodide heterojunction

5.1 Bismuth oxyiodide/semiconductor heterojunction

5.2 Bismuth oxyiodide/insulator heterojunction

5.3 Ternary heterojunction

6 Conclusion and outlook