Circularly polarized luminescence (CPL) as one of the optical properties of chiral materials, referring to the excited state properties of the chiral systems, has attracted much attention due to their potential applications in information encryption, high-resolution 3D displays and smart sensors. Besides the optical methods by applying a liner polarizer and a quarter waveplates, circularly polarized light could also be directly generated from chiral luminescent systems under excitation with photoluminescence or electroluminescence. Thus, a variety of CPL-active materials have been developed, including small molecular luminescence systems such as chiral organic molecules and coordination complexes, and chiral supramolecular assemblies. Self-assembly offers a powerful solution to obtaining the CPL-active materials with high quantum yields and dissymmetry factors. Responsive chiral assembled luminescent materials constructed by combining the chiral and responsive components play an important role in the development of intelligent CPL materials, reducing the tedious long synthesis process. Here, we summarize the responsive supramolecular chiroptical systems toward various stimuli, such as light irradiation, pH, solvent, temperature, mental ions, etc. This review is aimed to stimulate further academic and applied research and boost the practical applications of CPL materials in multidisciplinary fields.

As an important downstream product of furfural, furoic acid has important applications in food manufacturing, material preparation, optical technology and drug synthesis. It can be used to synthesize preservatives, plasticizers, thermosetting resins, spices and a variety of drugs. At present, there are many reviews on the preparation of furfural and the preparation of downstream compounds by hydrogenation. However, there is no systematic review on the oxidation of furfural to furoic acid. This paper reviews the progress in preparation of furoic acid from furfural in recent years. The effects of different catalytic systems and different oxygen sources on the selectivity of furoic acid are discussed. The application prospect of heterogeneous catalysts in the preparation of furoic acid is highlighted, and the future development direction of furoic acid preparation is prospected.

Sulfonyl chlorides are a class of important organic synthetic intermediates and have been widely applied in organic and medicinal synthesis. Sulfonyl chlorides have been utilized in organic reactions as important and powerful sources of sulfenes, sulfonyl, sulfenyl, aryl, and fluorinated alkyl groups. Reactions of sulfonyl chlorides with alkenes, alkynes, (hetero)aromatics, imines, halogenated aldehydes and ketones, and other unsaturated compounds are summarized in this review, including mainly [2+2] annulations, chlorosulfonylation, sulfonylation, sulfenylation, arylation, and fluoroalkylation. The further development on the reactions of sulfonyl chlorides and unsaturated compounds are discussed and predicted.

Reversible Addition-Fragmentation Chain Transfer Polymerization (RAFT Polymerization) is currently one of the most common “Reversible Deactivation Radical Polymerization”, and it has been widely used by scientists in different directions because of its advantages such as narrow molecular weight distribution, wide range of applicable monomers, and mild reaction conditions. However, when scientists choose RAFT chain transfer agents (also known as RAFT agents) in polymerization, they often donot clearly understand the principle of matching the activity of RAFT chain transfer agents and monomers. Therefore, in the preparation of block copolymers of “more activated” monomers (MAMs) and “less activated” monomers (LAMs), there are problems that the product has a wide molecular weight distribution, a slow polymerization rate, and even the reaction cannot successfully continue. Based on this, we first review the selection principles of RAFT chain transfer agents in polymerization, and then introduce the principle and application conditions of a universal RAFT chain transfer agent (Universal RAFT agent) (including non switchable type and proton switchable type) developed in recent years that is suitable for the polymerization of MAMs/LAMs. Finally, the latest development and application of block copolymers with MAMs and LAMs based on Universal RAFT agents are discussed in depth.

Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) are two porous crystalline materials, which have a large specific surface area, and high porosity and can be synthesized and modified via various methods. Therefore, they have found potential applications in hydrogen evolution, oxygen evolution, CO₂ reduction, organic pollution degradation, gas separation and so on. However, MOF and COF still have many defects themselves. For example, most MOFs are unstable in the aqueous solution due to the collapse of the structures; and COFs with no metals involved are poor in catalytic performance. Furthermore, COFs normally lack certain functions. As a new area, MOF-COF hybrid materials have been explored in recent years. They can combine the characteristics of the two materials to solve some of their own defects, and have a wide range of application prospects. Herein, this article summarizes the development of MOF-COF materials in recent years from three aspects: the types, synthetic methods and applications of MOF-COF hybrid materials. A prospect is also proposed.

The biological surfaces in nature can transport liquids in a given direction without any external energy or additional setup. Inspired by the natural surface, the liquid can be successfully transported by artificial surfaces. In recent years, liquid directional transportation has received extensive attention and in-depth research, and it is expected to have prospects in the fields of directional water collection, macroscopic liquid transportation, oil-water separation, microfluidic systems, etc. This review systematically introduces the principle of liquid transport, processing methods and potential application of biomimetic surfaces. Additionally, the limitations, challenges and future opportunities of liquid transportation are also scoped in this review.

Proton exchange membrane fuel cell is a green energy technology that can directly, efficiently and environmentally-friendly convert the chemical energy of fuel into electrical energy. Proton exchange membrane fuel cell has high energy conversion efficiency, fast startup, zero or low emissions. It is considered to be one of the most important energy alternative technologies in the post-oil era. Unfortunately, the current electrocatalysts suffer from high platinum loading and insufficient stability. The development of high-performance low-platinum catalysts is of great significance for reducing the cost of proton exchange membrane fuel cells and promoting the large-scale commercial application of proton exchange membrane fuel cells. Pt-based intermetallic compound is a kind of materials with determined stoichiometric ratio and regular atomic arrangement structure. It has been recognized as one of the most promising low-platinum catalysts, due to its much better catalytic activity and stability than corresponding disordered alloy materials and conventional Pt catalysts towards oxygen reduction reaction. In this paper, we have introduced the research progress of Pt-based intermetallic compounds catalysts from the aspects of catalytic mechanism, preparation technology, composition tuning, particle size tuning, morphology tuning and crystal structure in recent years, and the investigations on the application of intermetallic compounds in the oxygen reduction reaction of proton exchange membrane fuel cells. Moreover, the problems and challenges need to be overcome and addressed for the catalysts are pointed out, and a perspective for the research and development ideas and directions in the future is made.

In recent years, fluorescence imaging in the second near-infrared region (NIR-Ⅱ, 1000~1700 nm) has attracted lots of interests due to its unique advantages such as deep tissue penetration, low background and high spatial resolution. Commonly used NIR-Ⅱ probes such as small molecules, conjugated polymers and quantum dots, usually exhibit poor photostability, low quantum yield, small stokes shift and large half-peak width, which hinders the further development and application of NIR-Ⅱ imaging. Rare-earth based nanomaterials with unique optical properties have exhibited great potential for optical imaging. Rare-earth nanoparticles with metal ions as activators do not suffer from photobleaching and can provide narrow excitation/emission peaks with large stokes shift. Their emission is tuned with the choice of doped rare-earth ions and can maintain high quantum yield, which is different from other fluorophores. The fluorescence lifetime of rare-earth nanoparticles is also much longer than common fluorophores. All these features enable them as novel probes for in vivo fluorescence imaging and diagnosis in the NIR-Ⅱ region. This review briefly introduces the optical features of rare-earth nanoparticles, and discusses the design and application of NIR-Ⅱ emissive rare-earth nanoparticles according to the use of different sensitizers (Yb³⁺, Nd³⁺, Er³⁺ and Tm³⁺). Finally, the limitations and development direction of rare-earth nanoparticles in NIR-Ⅱ imaging are prospected.

Additive manufacturing, also known as three-dimensional (3D) printing, drives comprehensive innovations and upgrades in manufacturing, engineering, medicine, and other fields. 3D printing technology has made great progress in the biomedicine field in the past decade due to its ability to customize the complex 3D microstructures of organisms and construct biomimetic functional living tissues or artificial organs. In addition, silk fibroin (SF) is a natural organic polymer with abundant sources, biodegradable, excellent mechanical properties, and good cytocompatibility, which provides a promising choice for the design of 3D-printing inks. However, as a structural protein, single-component SF has limited physiological functions, and poor stability after printing, which limits the further development of SF in 3D printing and biomedical fields. For these reasons, researchers combined advanced 3D printing technologies with chemical modification methods to make the modified SF easy to be used for 3D printing and develop into a valuable biomaterial. Here, this article reviews the structural characteristics of SF, chemical modification strategies of SF, preparation strategies of printing inks and the latest application progress of 3D printed SF materials in the biomedical field. Meanwhile, we also look forward to the future development trend of 3D printed SF biomaterials, which provides a useful guideline for its application in a wider field.

“Yolk-shell” nanomaterials with adjustable “yolk”, "shell" and "cavity" structures are regarded as "nanoreactors" and have outstanding performance in the application fields of catalysis and energy storage. Especially for electrochemical energy storage and conversion, this type of material has a considerable specific surface area and a special core-shell structure, which could alleviate the volume change of the electrode, provide fast ions/electron transport channels, enhance the adsorption of intermediates, and strengthen the conversion reactions during the charge/discharge process. It can significantly improve electrode stability, rate and cycling performance, which is a relatively ideal electrode material. This article focuses on the application of “yolk-shell” nanostructured electrodes in the field of secondary batteries including lithium-ion batteries, sodium-ion batteries, and lithium-sulfur batteries and summarizes the design and synthesis strategies of this type of nanostructured electrodes, including template method, Ostwald ripening, Galvanic replacement, and Kirkendall effect, presents the advantages and disadvantages of various methods for electrochemical applications, and finally discusses prospects of yolk-shell structure in research and applications of lithium/sodium-based and lithium-sulfur secondary batteries.

Ultralight nanofiber aerogel is a new type of aerogel material with one-dimensional nanofibers as the basic building unit. Compared with traditional aerogels, it not only has a higher porosity and lower density but also with more excellent mechanical properties and physical and chemical properties thus the advanced preparation technology of this material and its innovative applications in emerging fields have become a research hotspot in the field of ultralight aerogels. Based on the research status, this paper systematically reviewed the preparation methods and structural characteristics of ultralight fiber aerogels and their important applications in the fields of thermal insulation, adsorption, electrode, sensing and biomedicine according to different materials systems. Moreover, some challenges faced by the material at this stage are put forward, and its future development direction has prospected.

Flow battery (FB), an important technology for large-scale energy storage, has the advantages of high safety, long cycle life, environmental friendliness, and so on. FBs can stabilize the fluctuation of renewable energy output, help to promote the large-scale application of renewable energy, and further achieve the goal of peak carbon dioxide emissions and carbon neutrality. Inorganic aqueous flow batteries with high energy efficiency and stable cycle performance are attracting increasing attention. This paper introduces the technology status and application demonstration of the commercial inorganic aqueous flow battery. Then, the principle, current state, and technology challenges of new-type inorganic aqueous flow batteries are summarized. Finally, this paper points out the goals of inorganic aqueous flow batteries for the next 15 years, pointing out the development direction of inorganic aqueous flow batteries.

Two-dimensional (2D) nanomaterials are nanomaterials with a sheet-like morphology, which have a nanoscaled thickness or even several atomic layers. There are many kinds of 2D nanomaterials and they have many physical and chemical properties different from bulk materials, so 2D nanomaterials have great potential in catalytic degradation, adsorption, filtration, sensor and so on, and can also be used for the prevention and control of environmental pollution. The properties of 2D nanomaterials can be controlled by modification of morphology, elements, groups, defects and material composite so as to improve their performance or develop new material systems. In this paper, the types of 2D nanomaterials are summarized first. The paper also focuses on the role and status of various 2D nanomaterials modification strategies, as well as the application of modified two-dimensional materials in the treatment of water pollution, air pollution, pollutant detection and so on. In a word, the paper makes a systematic introduction and prospect for the development of 2D nanomaterials in environmental governance.

Global warming and the energy crisis are posing increasingly severe risks for the economy, ecosystems and human health. As one kind of dominant greenhouse gas, carbon dioxide (CO₂) contributes most to global warming, while it is also considered as an abundant, nontoxic, and renewable C1 source. Thus far, transforming CO₂ into high value-added chemicals through modern technologies has attracted significant attention owing to its unique advantages. It can not only alleviate human reliance on fossil resources, but also effectively weaken the greenhouse effect. It is of great help to achieve China’s “dual-carbon” goal of “carbon peak and carbon neutrality”. N,N-Dimethylformamide (DMF), an extremely versatile solvent and important chemical intermediate, can be synthesized by using CO₂ and dimethylamine as raw materials over different catalysts. Therefore, the development of efficient catalytic systems is crucial for the transformation of CO₂ into high value-added products. This article reviews the current status and progress in the synthesis of DMF with CO₂ and dimethylamine with respect to reducing agents, catalytic systems as well as the reaction mechanisms of these different catalytic systems. Furthermore, we conclude the frontiers and future prospects of the catalytic synthesis of DMF from CO₂ and dimethylamine, providing readers a snapshot of this field.

Two-dimensional (2D) rhenium disulfide (ReS₂) is a layer-structured functional nanomaterial with atomic thickness and few lattice symmetry elements. The low symmetry of the crystal structure endows 2D ReS₂ with rich anisotropic physical and chemical properties, giving it great potential in the fieldsof nanophotonics, tactile sensors, and anisotropic electronic devices. The applications of 2D ReS₂ rely on high-quality synthesis and a deep understanding of its properties. This review firstly categorizes the chemical vapor deposition (CVD) methods of ReS₂ into three groups based on the types of the metallic and non-metallic precursors applied in the growth, as well as the substrates. Different CVD strategies and the corresponding growth mechanisms are systematically summarized. Subsequently, the recent progress in the preparation of ReS₂ in-plane and vertical 2D heterostructures is introduced. Approaches are divided into “one-step method” and “two-step method” based on the number of steps used in the CVD process. Finally, the anisotropic optical and electronic properties of 2D ReS₂ are discussed. This review also puts forward an outlook on the challenges and opportunities of the synthesis and property investigation of 2D ReS₂.