The research focus of spintronics is to process and store the information by manipulating both the charge and spin degrees of freedom for its advantages of fast device operation, high storage density and low energy consumption. It is no doubt that developing controllable preparation method and magnetism control strategy of two-dimensional (2D) magnetic nanomaterials are of great significance and value for the fabrication of new-type spintronic devices. However, a relatively limited range of 2D magnetic nanomaterials can be achieved yet, and the preparation method as well as magnetism control strategy are relatively unvarying, which greatly hinders the development of this field. In this review, 2D magnetic nanomaterials are first categorized according to the origin of the magnetism, and induced magnetism and intrinsic magnetism in 2D nanomaterials have been introduced respectively. Then the existing preparation methods of the 2D magnetic nanomaterials, such as mechanical exfoliation, electrochemical exfoliation, chemical vapor deposition, liquid-phase synthesis and so on, are summarized in detail. Afterwards, the predominant magnetism control strategies of 2D nanomaterials are highlighted as well. Finally, the bottlenecks and future developments of this booming field are outlined and prospected.

As one booming category of smart polymeric materials, stimuli-responsive liquid crystal elastomers (LCEs) are very promising owing to the large and reversible shape deformations response to external stimuli (heat, light, electric or magnetic field, etc.). Due to the changes of microscopic orders or molecular structures of uniaxial-aligned mesogens, the whole LCE materials could execute very large and reversible macroscopic actuation during the LC-to-isotropic phase transition process. Among them, near-infrared light (NIR-light) responsive LCEs have attracted scientific attention because NIR-light has a strong penetration and low toxicity to biological tissues. The NIR-induced deformation mechanisms of LCEs can be divided into two main categories. One is relying on the trans-cis variations of azobenzene chromophores triggered by NIR-light which can be converted into low-wavelength lights by doping inorganic or organic up-conversion materials. The other type of light-responsive LCEs takes advantage of the photo-thermal effect of thermal conductive fillers to transform light into heat which further induces the LC-to-isotropic phase transition and thus make the LCE materials shrink/expand. These characteristics endow NIR-light responsive LCE materials with potential applications as mechanical actuators, artificial organs, smart surfaces, microrobots, etc. This article reviewes the developments of NIR-light responsive LCEs, and also introduces the main deformation mechanisms and applications of NIR-light responsive LCEs in detail. Besides, the article further provides a view of prospective development in future for NIR-light responsive LCEs and actuators.

The reverse osmosis concentrates (ROCs) with high concentration of chemical oxygen demand and salts are produced by a double-membrane technology, which has been widely used to treat the wastewaters from petroleum refinery enterprises. The ROCs are prohibited from directly discharging from environmental point of view and must be treated to comply with the tighter discharge limits of wastewater and solid wastes per the upgrading national emission standard. Therefore, effective technologies for the removal of organic matter and recovery of salts from ROCs have been committed to be developed. In this review, the recent progress on the treatment technologies of ROCs from petroleum refinery waste waters are summarized and discussed. Firstly, the compositions of ROCs, the basis of developing the treatment process, from several petroleum refinery plants are collected and analyzed. Subsequently, the removal methods of organic contaminants, such as physicochemical method, advanced oxidation method, and biochemical method, are elaborated in detail. Especially for some innovative advanced oxidation processes, including O₃ oxidation, Fenton method, electrochemical oxidation, photocatalytic oxidation, and ozonation-based combination processes, and their mechanisms, advantages and disadvantages for the treatment of ROCs from industrial sources are emphasized comprehensively. Finally, the methods of salts’ recovery from ROCs are also discussed briefly.

Heterogeneous catalytic conversion of carbon dioxide(CO₂) into high value-added fine organic chemicals and chemical fuels has been indicated the important research value and industrial application potential. Due to their high specific surface area, ordered channel structure, excellent chemical and thermal stability, controllable catalytic sites, covalent organic frameworks(COFs) as an emerging class of organic materials, have exhibited outstanding advantages for adsorption and conversion of CO₂. Specifically functional molecules or catalytic sites can be easily incorporated into the channel or surface of COFs by using rational strategy, which can efficiently and purposefully achieve the selective regulation for the specific reactions and provide a favorable microenvironment for substrates transport in reaction process. These merits thus can endow promising catalytic performance for heterogeneous catalysis, which greatly give rise to the rapid development and have a good application prospect for the catalytic conversion and utilization of CO₂ over COFs catalysts. Therefore, this review briefly focuses on the advances of the conversion of CO₂ into important fine chemicals and chemical fuels over COFs in recent years and proposes the key scientific issues involved in this field. Moreover, we also attempt to propose an outlook on the prospective developments for the CO₂conversion and utilization by using COFs catalytic materials.

Surface structure plays a vital role in the functionalization of polymer. In the past decades, various functional surfaces with diversified microstructures have been fabricated through electrospinning, lithography, plasma processing to achieve wide applications in optics, electronics, biology, chemistry and so on. However, there is still a huge demand to develop new strategies for regulating polymer’s surface microstructure to meet the growing requirements of economic and technological development. This review gives a brief instruction of current research on controlling surface structure from the perspectives of molecule diffusion, internal stress, external stress, and the cooperation of these different factors. Besides, the future development in controlling surface microstructure of polymer materials has been discussed.

Lithium-rich manganese-based layered cathode materials (xLi₂MnO₃·(1-x)LiMO₂, M=Ni, Co, Mn, etc.), owing to their high specific capacity (≥ 250 mAh·g^-1), low cost and environmental friendliness, are considered as one of the best candidate cathode materials for the new generation of lithium-ion batteries. However, these materials suffer from severe capacity/voltage fading during the cycle process and low rate capability which seriously hinder commercial development. In this paper, we analyze the structural characteristics and the reasons which lead to the deterioration of the electrochemical performance of the lithium-rich manganese-based layered cathode materials, systematically review the latest progress and achievements on improving the stability of the cathode materials, and the efforts to improve the electrochemical properties of the cathode materials through bulk doping and surface modification. In this process, the effects of bulk doping at different sites and different coating materials on the structure and electrochemical behavior of lithium-rich manganese-based layered cathode materials are further analyzed. Finally, considering the advantages and disadvantages of the two modification methods of bulk doping and surface coating, a joint modification mechanism combining bulk doping and surface coating has been suggested to improve the stability of lithium-rich cathode materials in the long cycle process, and the introduction and prospect of this mechanism are also given.

A non-biased photoelectrochemical (PEC) cell composed of both an n-type semiconductor photoanode and a p-type semiconductor photocathode offers a cost-effective route to convert water directly into high energy density hydrogen using solar energy, which helps address the intermittency and storage problem of solar energy during utilization. Metal oxide semiconductors have the advantages of low cost and facile preparation. Compared with well-developed n-type metal oxide photoanode materials, the stability of conventional p-type metal oxide photocathode materials still remains a challenge due to the photoelectrochemical reduction of metallic ions. As a new type of metal oxide photocathodes, ferrite photocathodes have recently emerged as competitive candidates for practical applications due to the appropriate band gaps, better photostability, higher onset potential and relatively low preparation costs. In this review, the fundamentals of PEC water splitting and common methods for improving performance of photoelectrodes are first introduced, and the recent progress of representative CuFeO₂, CaFe₂O₄ and LaFeO₃ photocathodes are summarized, including their fabrication methods, elements doping and surface modifications. Finally, perspectives on the future development of ferrite photocathodes are also discussed.

As an important reactive trace gases in the troposphere, nitryl chloride (ClNO₂) has significant impacts on atmospheric oxidation capacity, the degradation of primary pollutants and the formation of secondary pollutants, and plays indispensable roles in global cycles of both nitrogen and chlorine. In this paper, we introduce basic properties of ClNO₂ as well as its formation and removal mechanisms in the troposphere, and describe in brief techniques currently used in laboratory and field work to measure ClNO₂. In addition, we review spatial and temporal distributions of tropospheric ClNO₂ over the globe as reported in the last 10~20 years, discuss in a systematical manner chemical mechanisms and environmental factors which determine its heterogeneous formation in the atmosphere via critical analysis of important results from laboratory studies and field measurements, and summarize impacts of ClNO₂ on chlorine radicals, atmospheric oxidation capacity as well as the formation of O₃ and nitrate aerosol. We emphasize that ClNO₂ couples gas phase chemistry and heterogeneous chemistry, and also couples nocturnal atmospheric chemistry with daytime photochemistry, thus very likely playing an important role in the formation of air pollution complex in China. Important questions which remain to be answered to better understand atmospheric chemistry of ClNO₂ are outlined at the end, and we also discuss in brief how these questions can be addressed in future work.

As one of the most abundant biomass resources in nature, lignin has not been fully utilized, which has become a challenge to the development of biochemical industry. As an important strategy to achieve high-value utilization of lignin, grafting modification of lignin has been paid much attention. Ring-opening polymerization is a mild and efficient polymerization method, which can introduce aliphatic polyester segments into lignin. Compared to the pristine lignin, graft polymers show improved solubility, compatibility and degradability. This paper focuses on the progress of grafting modification of lignin via ring opening polymerization by using varied catalysis. Lactide, caprolactone and other cyclic monomers are summarized. The performance and applications of lignin grafted polymers are discussed as well as the challenges and opportunities.

Microbial extracellular electron transfer (EET) is the process that electroactive microorganisms transfer electrons to an extracellular electron acceptor or receive electrons from the environment. EET is essential for interspecies electron transfer and also contributive to the biogeochemical cycling of elements and biotechnological applications in environments. Up till now, research on EET has been concentrated on Gram-negative electroactive bacteria, however, the EET pathway of Gram-positive electroactive bacteria remains limited. As the membrane structure between Gram-positive bacteria and Gram-negative bacteria are significantly different, the types of redox proteins and electron shuttles involved in the transmembrane transfer may be different. Gram-positive bacteria are widely distributed among environment and they can proceed EET in harsh condition e.g. high temperature, low pH, high pH and high salinity, therefore their electroactivity and EET have attracted great attention. In this review, we summarize the types of Gram-positive electroactive bacteria EET pathway, which include direct electron transfer and mediated electron transfer, the same as Gram-negative bacteria, but Gram-positive bacteria have much more diversities on redox proteins and electron shuttles. We elaborate recent development of EET pathways of Firmicutes, Actinobacteria and Chloroflexi, describe the applications in the degradation of pollutants, bio-electricity generation and biofuel production, then propose possible research directions in the future.

Recently, covalent organic frameworks(COFs) materials have received considerable attention by scholars for their superior characteristics of stable and modifiable structure, high specific surface area, large porosity, and easy functionalization. By controlling the pore size, shape and linkage of COFs materials, as well as the post-synthetic modification, the functional COFs materials have excellent performance in broad areas of gas storage and separations, sensors, drug delivery, etc. Especially in the fields of environmental chemistry, the COFs materials are posing noteworthy concerns in their environmental application. This article reviews the structure control, classification of COFs materials and their application in detecting and removing pollutants, including adsorption and catalysis of heavy metal ions, radionuclides, organic and gaseous pollutants. By changing the size and shape of building units, as well as introducing special functional groups and active sites, the interaction between pollutants and COFs materials have been strengthened via hydrogen bonds, π-π interaction, Van der Waals forces, etc. Consequently, the COFs materials have excellent performance in environmental applications. Eventually, the application prospects and future research directions of COFs materials in the field of environmental remediation are prospected, which may be helpful for future related research.

With the advantages of ultra-high power density, and super specific capacitance, nickel sulfides pseudocapacitors have been supposed as one of the ideal devices for energy storage. However, the application of those pseudocapacitors have been subjected to the poor cycle stability and low conductivity. Up to now, extensive efforts have been made to increase the conductivity and cycle stability. Among which, the self-supported electrode materials have been regarded as a effective solution to reduce internal resistance for high rate capacitance. This paper reviews the main methods to prepare self-supported nickel sulfides pseudocapacitor electrode materials, and summarize the relationship between morphology and capacitance property, which focus on the modification of conductive substrates, the compositing with graphene or others elements, the design of flexible materials, etc. Finally, the research directions of these materials are further proposed.

The development of flexible and wearable sensors in the past decade has made them have good application prospects in personalized medicine, human-computer interaction and intelligent robots. Flexible conductive polymer composite materials composed of conductive materials and elastic polymers, which have high stretchability, excellent flexibility, durability and other characteristics, can be used to prepare flexible sensors with wide sensing range and high sensitivity. This article reviews the composite types (filled type strain sensors, sandwich type strain sensors, adsorption type strain sensors) and sensing mechanisms (tunneling effect, disconnection mechanism, crack propagation) of stretchable strain sensors based on flexible conductive polymer composite materials. The structure design of the composite materials used for the sensor is introduced in detail, including the internal structure (double percolation structure, segregation structure, porous structure, and “brick-and-mortar” structure), surface structure (wrinkles structure and microcrack structure) and macro structure (fiber structure, net structure, film structure). The internal structure design can reduce the materials’ percolation threshold, the surface structure design can improve the sensor performance, and each macro structure has its own characteristics. Finally, the developments of the sensors in material selection, preparation technology, structure design, compound mode, additional performance and application direction are prospected.

In recent years, organic-inorganic hybrid perovskite materials based on the ABX₃ structure have attracted worldwide attention due to their excellent optoelectronic properties and cheap manufacturing costs. However, the organic components in the system are elementary to be resolved under the influence of light, heat, humidity, and other external conditions, which greatly limits the industrialization of the PSCs(Perovskite solar cells). All-inorganic perovskite materials prepared by using pure inorganic cations to replace the A-site organic cations in ABX₃ structure have been developed rapidly due to their excellent thermal stability and environmental stability. At present, the efficiency of all-inorganic perovskite solar cells(I-PSCs) has exceeded 19% with broad application prospects. The research progress of inorganic perovskite materials and the different types of inorganic perovskite materials are reviewed. Meanwhile, the ways to improve the stability of devices from the aspects of films forming process, doping engineering, post-processing engineering, etc. are summarized Finally, we introduced the large-area preparation and flexible application of I-PSCs, reveals the challenges faced by I-PSCs and summarizes the prospect of the field.