State Key Laboratory of Solid Lubrication

Oil spills and industrial organic pollutants have induced severe water pollution and threatened every species in the ecological system. To deal with oily water, special wettability stimulated materials have been developed over the past decade to separate oil-and-water mixtures. Basically, synergy between the surface chemical composition and surface topography are commonly known as the key factors to realize the opposite wettability to oils and water and dominate the selective wetting or absorption of oils/water. In this review, we mainly focus on the development of materials with either super-lyophobicity or super-lyophilicity properties in oil/water separation applications where they can be classified into four kinds as follows (in terms of the surface wettability of water and oils): (i) superhydrophobic and superoleophilic materials, (ii) superhydrophilic and under water superoleophobic materials, (iii) superhydrophilic and superoleophobic materials, and (iv) smart oil/water separation materials with switchable wettability. These materials have already been applied to the separation of oil-and-water mixtures: from simple oil/water layered mixtures to oil/water emulsions (including oil-in-water emulsions and water-in-oil emulsions), and from non-intelligent materials to intelligent materials. Moreover, they also exhibit high absorption capacity or separation efficiency and selectivity, simple and fast separation/absorption ability, excellent recyclability, economical efficiency and outstanding durability under harsh conditions. Then, related theories are proposed to understand the physical mechanisms that occur during the oil/water separation process. Finally, some challenges and promising breakthroughs in this field are also discussed. It is expected that special wettability stimulated oil/water separation materials can achieve industrial scale production and be put into use for oil spills and industrial oily wastewater treatment in the near future.

Mussel-inspired chemistry, owing to its unique and versatile functions to manipulate dynamic molecular-scale interactions, has emerged as a powerful tool for the rational design and synthesis of new hydrogels. In particular, possessing a myriad of unique advantages that are otherwise impossible by conventional counterparts, mussel-inspired hydrogels have been widely explored in numerous fields such as biomedical engineering, soft electronics and actuators, and wearable sensors. Despite great excitement and vigor, a comprehensive and timely review on this emerging topic is missing. In this review, we discuss (1) the fundamental interaction mechanisms underpinning the spectacular wet adhesion in natural mussels and mussel-inspired materials; (2) the key routes to engineering hydrogels by leveraging on the interactions of mussel-inspired building blocks; (3) the emerging applications of mussel-inspired hydrogels, especially in the areas of flexible electronics and biomedical engineering; (4) the future perspectives and unsolved challenges of this multidisciplinary field. We envision that this review will provide an insightful perspective to stimulate new thinking and innovation in the development of next-generation hydrogels and beyond.

Novel composites of Ni-MOF/CNTs and rGO/C₃N₄were synthesized to assemble an asymmetric supercapacitor with high energy and power density.

Ionic liquids (ILs) have emerged as potential lubricants in 2001. Subsequently, there has been tremendous research interest in ILs from the tribology society since their discovery as novel synthetic lubricating materials. This also expands the research area of ILs. Consistent with the requirement of searching for alternative and eco-friendly lubricants, IL lubrication will experience further development in the coming years. Herein, we review the research progress of IL lubricants. Generally, the tribological properties of IL lubricants as lubricating oils, additives and thin films are reviewed in detail and their lubrication mechanisms discussed. Considering their actual applications, the flexible design of ILs allows the synthesis of task-specific and tribologically interesting ILs to overcome the drawbacks of the application of ILs, such as high cost, poor compatibility with traditional oils, thermal oxidization and corrosion. Nowadays, increasing research is focused on halogen-free ILs, green ILs, synthesis-free ILs and functional ILs. In addition to their macroscopic properties, the nanoscopic performance of ILs on a small scale and in small gaps is also important in revealing their tribological mechanisms. It has been shown that when sliding surfaces are compressed, in comparison with a less polar molecular lubricant, ion pairs resist "squeeze out" due to the strong interaction between the ions of ILs and oppositely charged surfaces, resulting in a film that remains in place at higher shear forces. Thus, the lubricity of ILs can be externally controlled in situ by applying electric potentials. In summary, ILs demonstrate sufficient design versatility as a type of model lubricant for meeting the requirements of mechanical engineering. Accordingly, their perspectives and future development are discussed in this review.

An “acetonitrile/water in salt” electrolyte with non-flammability, high conductivity, a high stability window and a wide applicable temperature range enables high-performance supercapacitors.

Superhydrophobic nanocoatings, a combination of nanotechnology and superhydrophobic surfaces, have received extraordinary attention recently, focusing both on novel preparation strategies and on investigations of their unique properties. In the past few decades, inspired by the lotus leaf, the discovery of nano- and micro-hierarchical structures has brought about great change in the superhydrophobic nanocoatings field. In this paper we review the contributions to this field reported in recent literature, mainly including materials, fabrication and applications. In order to facilitate comparison, materials are divided into 3 categories as follows: inorganic materials, organic materials, and inorganic-organic materials. Each kind of materials has itself merits and demerits, as well as fabrication techniques. The process of each technique is illustrated simply through a few classical examples. There is, to some extent, an association between various fabrication techniques, but many are different. So, it is important to choose appropriate preparation strategies, according to conditions and purposes. The peculiar properties of superhydrophobic nanocoatings, such as self-cleaning, anti-bacteria, anti-icing, corrosion resistance and so on, are the most dramatic. Not only do we introduce application examples, but also try to briefly discuss the principle behind the phenomenon. Finally, some challenges and potential promising breakthroughs in this field are also succinctly highlighted.

With the advantages including wide ESW, superior conductivity, low viscosity and low cost, NaClO₄-based WIS electrolyte can be considered as a promising candidate for high-voltage and high-rate aqueous carbon based SCs with good safety.

A new hybrid supercapacitor with excellent electrochemical performance is fabricated by using the flower-like Co(OH)₂ and urchin-like VN.

The limitations of traditional separation technology force people to find a more advanced separation technology, while the special wetting material has attracted the attention of most researchers.

Through 3.7 billion years of evolution and natural selection, plants and animals in nature have ingeniously fulfilled a broad range of fascinating functions to achieve optimized performance in responding and adapting to changes in the process of interacting with complex natural environments. It is clear that the hierarchically organized micro/nanostructures of the surfaces of living organisms decisively manage fascinating and amazing functions, regardless of the chemical components of their building blocks. This conclusion now allows us to elucidate the underlying mechanisms whereby these hierarchical structures have a great impact on the properties of the bulk material. In this review, we mainly focus on advances over the last three years in bioinspired multiscale functional materials with specific wettability. Starting from selected naturally occurring surfaces, manmade bioinspired surfaces with specific wettability are introduced, with an emphasis on the cooperation between structural characteristics and macroscopic properties, including lotus leaf-inspired superhydrophobic surfaces, fish scale-inspired superhydrophilic/underwater superoleophobic surfaces, springtail-inspired superoleophobic surfaces, and Nepenthes (pitcher plant)-inspired slippery liquid-infused porous surfaces (SLIPSs), as well as other multifunctional surfaces that combine specific wettability with mechanical properties, optical properties and the unidirectional transport of liquid droplets. Afterwards, various top-down and bottom-up fabrication techniques are presented, as well as emerging cutting-edge applications. Finally, our personal perspectives and conclusions with regard to the transfer of micro- and nanostructures to engineered materials are provided.

It is well known that high optical transparency is one of the most crucial criteria for the overwhelming majority of optical devices and correlative functions, including smart windows, camera lenses, solar cell systems and optoelectronic devices. With the frequent exposure of this equipment to all sorts of environments, such as outdoor conditions, a surface with self-cleaning properties can guard against fouling, humidity, bacterial growth and so forth. That is one type of application of the big family of superhydrophobic coatings. Therefore, integrating high transparency with self-cleaning characteristics is of great importance for such applications. In this review, the recent developments in designing, synthesizing and manufacturing transparent and superhydrophobic surfaces are reviewed. Firstly, the established theoretical aspects of surface wetting properties are summarized and then several natural and bio-inspired superhydrophobic surfaces of diverse microcosmic structures are presented as representative examples. With a focus on distinctively employed materials and the corresponding fabrication of superhydrophobic coatings with high transparency, the promising research directions and application prospects of this rapidly developing field are briefly addressed as well.

Here, the water-collecting materials inspired by the three typical and widely-researched creatures (cactus, spider, desert beetle) are first introduced. Then, another eight animals and plants (butterfly, shore birds, wheat awns, green bristlegrass bristle, <italic>Cotula fallax</italic> plant, Namib grass, green tree frogs and Australian desert lizards) that are rarely reported are followed to be complemented.

Recent progress in the fabrication and applications of biomimetic superoleophobic surfaces are mainly reviewed, and current and further challenges for biomimetic superoleophobic surfaces are also proposed.

This review places an emphasis on chitosan intelligent hydrogels. The fabrication methods and mechanisms are introduced in this review and the interactions of the formation of hydrogels with both physical and chemical bonds are also introduced. The relationship between the structural characteristics and the corresponding functions of stimuli-responsive characteristics, self-healing functions and high mechanical strength properties of the chitosan hydrogels are discussed in detail.

With the help of CNF conductive bridges, Ti₃C₂/CNF hybrid particles exhibited significantly enhanced reversible capacity and excellent rate performance.

Wettability is a special character found in nature, including the superhydrophobicity of lotus leaves, the underwater superoleophobicity of fish scales and the slipperiness of pitcher plants. These surfaces exhibit unique properties such as resistance to icing, corrosion, and the like. The antifouling properties of the material surface have important applications in a variety of areas, such as in hulls, in medical equipment, in water pipes and underwater equipment. However, the traditional anti-fouling surface is usually combined with toxic substances or its manufacturing process is complicated and expensive, which cannot meet the current antifouling demand. These wettable surfaces have always exhibited good anti-biofouling and self-cleaning properties, and their use as antifouling surfaces can well solve the problems of the above-mentioned traditional antifouling surfaces. Here, we divided the wettable surfaces into superhydrophobic surfaces, underwater superoleophobic surfaces and slippery surfaces, respectively, summarizing their development in the field of antifouling. Their research progress in antibacterial, antibiotic flocculation and antiplatelet adhesion is highlighted. Furthermore, we provide our own insights into the shortcomings and development prospects of wettable surface applications in the field of antifouling.

We describe a simple yet extremely versatile and generalized surface polymer modification approach based on a surface initiated polymerization from a polydopamine (PDA) layer. PDA deposits on virtually any substrate independent of specific surface chemistries and can act as a photoinitiating layer to initiate the radical polymerization of a variety of (methyl)acrylic/styrene monomers. It does not require any metal/ligand catalyst, additional photoinitiator or dye sensitizer. Another attractive feature of this novel strategy is the ability to spatially control the architectures (pattern, gradient) of the polymer films by altering the areas of light irradiation. It is also adaptable to large area grafting with an ultra-small amount of monomer solution (a thin monomer solution layer).

Inorganic adhesives are presented to construct robust, self-healing, superhydrophobic surfaces. The surfaces maintain superhydrophobicity after physical abrasion, and still show excellent mechanical robustness after treatment under harsh conditions. They also have a rapid self-healing ability against boiling-water treatment, O₂-plasma etching, and amphiphilic pollution.

A high-temperature flexible supercapacitor, which shows excellent electrochemical energy-storage ability and flexibility at high temperature, is constructed.

As a member of the liquid electrolyte family, ionic liquids (ILs) possess distinctive chemical and electrochemical stability, offering a pathway to realize supercapacitors (SCs) with both outstanding energy density and high safety.