Lithium-ion batteries(LIBs) have been widely used in portable electronic devices and electric vehicles owing to their characteristics of high energy density, safety, and long lifetime. Titanium dioxide(TiO₂) is a promising anode material for LIBs due to the advantages of non-toxicity, low cost, abundant sources, and stable chemical structure. However, intrinsic low electronic conductivity and poor lithium-ion(Li⁺) diffusion have restricted its development for practical applications. In this review, we firstly systematically summarize the lithium storage mechanisms of three common TiO₂ polymorphs, that is, a two-phase solid solution of anatase TiO₂, intrinsic pseudo-capacitance of TiO₂(B), and potential-dependent phase transition of rutile TiO₂. Furthermore, to enhance the electron conduction and Li⁺ diffusion, the research progress of nanostructure dimensional tailoring, intrinsic/extrinsic electronic structure manipulation(elemental doping, Ti³⁺ self-doping, and modification of highly conductive materials), and hetero-phase junction optimization are discussed in detail. Finally, the development trend and application prospect of TiO₂ anode materials for LIBs and beyond-LIBs are proposed.

Water splitting using the electricity from renewable energy sources offers a clean and sustainable way to produce H₂ and meanwhile an advanced energy conversion technology. Thus it is expected to play a vital role in the future clean energy economy. Crucial to enabling this ideal vision is the development of high-performance and cost-effective electrocatalysts for the hydrogen evolution reaction(HER) and oxygen evolution reaction(OER). Molybdenum disulfide(MoS₂) is a representative non-precious HER catalyst. A panoramic view of its researches and developments clearly shows that leading theoretical perspectives, logical material design, novel synthesis methods and advanced characterization technologies are the key components of a successful electrocatalyst implementation. At the same time, it also reflects the current research mode and points out the development directions of the electrocatalysts. This review covers a sequence of key discoveries and achievements that mark the development of MoS₂ as a HER electrocatalyst, with special focuses on the implementation, effect and mechanism of the modification strategies including increasing the number of active edge sites, improvement of electrical conductivity and activation of inert basal planes. Finally, we briefly discuss the enlightenment from the studies of MoS₂ electrocatalyst and look forward to the future trends of this appealing electrocatalytic material.

Ultra-thin two dimensional metal-organic framework(MOF) nanomaterial is a kind of MOF materials. Different from the traditional bulk MOF materials, the ultra-thin sheet structure endows it with unique properties such as high specific surface area, rich coordination unsaturated metal sites and so on, which can effectively improve the performance of MOF in catalysis, separation and sensors. In this paper, the research progress on the construction and preparation methods of ultra-thin two dimensional MOF nanomaterials in recent years is reviewed, including top-down method, bottom-up method and 2D oxide sacrifice approach. At the same time, this paper discusses the application prospects of ultra-thin two dimensional MOF nanomaterials in the fields of gas adsorption and gas separation, catalysis, energy storage, sensing platform, and further analyzes the challenges and opportunities faced by the research of ultra-thin two dimensional MOF nanomaterials in the future.

Cellulose nanocrystal(CNC) is a nano-scaled rod-like or spherical crystal isolated from cellulosic materials. CNC has shown many advantages of, for example, high strength, high specific surface area, biocompatibility, renewability and degradability. Therefore, it can be applied to the composite materials, biomedicine and environment fields. The preparation methods of CNC are detailedly summarized in this review such as acid hydrolysis, oxidation method, enzymatic hydrolysis, mechanical method, solvent methods and combined processes. Meanwhile, the advantages and shortcomings of the preparation methods are discussed. In the field of applied research, this review summarizes the research status of CNC in some popular fields such as reinforced composite materials, membrane filtration composite materials, conductive composite materials and inorganic nanocomposites. Finally, the future prospective of CNC is presented.

Since the 1980s, the advanced oxidation process(AOP) in water treatment technology has been widely researched and applied. However, organic pollutants in water still plague scholars due to their wide variety and difficulty in degradation. Therefore, the mechanism of AOP needs to be clearly understood and get deeper into, which is conducive to technological application. As a typical AOP, the peroxymonosulfate & peroxydisulfate oxidation process has received a lot of attention in recent years, whereas there are still numerous disputes on the mechanism, lacking a unified understanding. The key reactive species of free radical process are generally ·OH and ·SO₄^-. Nonradical process contains ¹O₂ oxidation and peroxymonosulfate & peroxydisulfate oxidation(known as an electron transfer process), and high valence metal also participates in the oxidation process directly or indirectly. The specific mechanism of nonradical processes are still controversial, also the advantages and disadvantages. For the above reasons, this paper reviews the latest researches on the treatment of organic pollutants based on heterogeneous catalytic persulfate oxidation process in water, explains the reaction mechanism and the analysis methods, and points out the possible current research problems. Prospects for the future research direction and the application perspective of persulfate oxidation are proposed, with an emphasis on nonradical processes.

As a class of persistent organic pollutants, polycyclic aromatic hydrocarbons(PAHs) have been widely distributed in soil, which is highly stable, hydrophobic, cytotoxic and difficult to degrade. The PAHs are commonly produced from transportation, industrial production and waste incineration. In recent years, the increasingly serious pollution of PAHs in soil has become a great threat to soil ecology, food safety and public health. Hence, the treatment of PAHs contaminated soil is of great importance and urgently needed. Among numerous strategies for PAHs degradation, photocatalytic technology has attracted extensive attention due to its low energy consumption, facile operation and environmental friendliness. In this paper, the photocatalytic degradation mechanism and pathway of PAHs are overviewed, the current state of knowledge concerning photocatalytic remediation of PAHs contaminated soils is reviewed, and the impacts of different environmental factors on the degradation efficiency of photocatalysts are discussed. Furthermore, we summarize the challenges to apply photocatalytic technology in the field of PAHs contaminated soil remediation.

As a novel type of Bi(Ⅲ)-based semiconductor photocatalyst, bismuth molybdate(Bi₂MoO₆) possesses the advantages of layered structure, low cost, cleanness and efficiency, narrow band gap and visible light response, etc. Resultantly, it exhibits widely potential applications in various photocatalytic areas such as degradation of water pollutants, air purification, antibacterial, water splitting, carbon dioxide reduction and nitrogen fixation. However, there are still two main bottleneck problems which would restrict the practical applications of Bi₂MoO₆ and needs to be addressed urgently. One is the low absorption efficiency for solar energy and the other is the fast recombination rate of photogenerated electron-hole pairs. Introduction and regulation of structure defects in Bi₂MoO₆ have been proved to be effective strategies to resolve the above problems. In the paper, the research progress of Bi₂MoO₆ defect engineering in recent years is comprehensively reviewed, including elemental doping, oxygen vacancy, synergistic effects, etc. The different methods to construct defects in Bi₂MoO₆ and the corresponding photocatalytic properties are extensively summarized. Also, the structure-activity relationship and action mechanism of the structural defects in different research fields are in-depth discussed and concluded. Finally, the present shortcomings of defective Bi₂MoO₆ photocatalyst are analyzed and the development direction and prospects in future are prospected.

Liquid lithium-ion batteries have fatal safety problems such as flammability, explosion, and short-circuit, as well as technical problems such as cruising range anxiety. The development of lithium-ion batteries with good safety performance and high energy density is an urgent need for industrial development. Compared with traditional liquid lithium-ion batteries, all-solid-state batteries have the advantages of safe use and high theoretical specific capacity, so they have been extensively studied and are known as the mainstream technology of next-generation batteries. Among them, the inorganic solid electrolyte plays an important role in the all-solid-state battery, and scientific researchers at home and abroad have conducted a lot of research work on this. This article introduces the latest developments in different types of inorganic solid electrolytes, including oxide solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes. The researches on interface problems, crystal structure, preparation methods, and doping modification of inorganic solid electrolytes are also elaborated. Finally, the problems to be solved in inorganic solid electrolytes in recent years are discussed, and the future research directions are also given.

All-inorganic cesium lead halide perovskite CsPbX₃(X = Cl, Br, I) nanocrystals, as a new generation of low cost and direct band gap semiconductor materials, have attracted extensive attention of researchers owing to their outstanding photoluminescence(PL) performance, solution processability, and defect tolerance. Especially, this new emerged materials show arresting optoelectronic properties, such as high absorption coefficient, size- and composition-dependent tunable band gaps from the violet to near-infrared, extremely narrow full width at half-maximum, and high photoluminescence quantum yields(PLQY). Many potential optoelectronic applications have been demonstrated as illumination, energy, information storage and detection. In this review, we mainly focus on the related crystal structure characteristics of CsPbX₃ nanocrystals, the various colloidal synthesis of monodisperse CsPbX₃ nanocrystals including the high temperature hot-injection method, room-temperature recrystallization method, solvothermal method, droplet-based microfluidic method, postsynthetic halide anion exchange reaction, and so on. We also summarize the common strategies for efficiently controlling different morphology and size via controlling the temperature and the capping ligands. The related methods to enhance the stability are also summarized. In addition, we carefully conclude the optoelectronic device of CsPbX₃ nanocrystals in white light-emitting diodes(WLEDs), electroluminescent light emitting diodes(LEDs), lasers especially in low-threshold amplified spontaneous emission, photodetectors, high-efficiency solar cells, and other optoelectronics fields. Finally, the existing problems and prospects are also provided in detail.

The energy density and safety of lithium secondary batteries are urgently required to be improved. Research on high-energy-density solid-state lithium batteries is of great significance to development of the new energy industries. Compared with the traditional organic electrolyte lithium-ion battery, the solid-state lithium battery with polymer solid electrolyte not only has significantly improved security, but also can match with high-capacity electrode materials to effectively improve the energy density. The polymer-based solid-state lithium battery is one of the most promising lithium secondary batteries. However, there are still some problems between polymer solid electrolyte and lithium anode, such as interface side reaction and lithium dendrites. In recent years, various methods have been used to improve the performance of solid-state lithium battery, including electrolyte composition regulation, electrolyte mechanical properties improvement, electrolyte/lithium anode interface regulation and matching three-dimensional lithium anode. Here, the common polymer solid electrolyte and its interface challenges with lithium anode are firstly introduced. Simultaneously, the recent research progress on improving the interface stability of polymer electrolyte/lithium anode is summarized and discussed in detail, including: adding inorganic fillers, using high-strength substrate film, building hierarchical layered structure, constructing interfacial buffer layer, designing and developing electrolyte with cross-linking network structure and fabricating protected solid-state lithium anode. Finally, the research and development trend of polymer solid electrolyte/lithium anode interface compatibility are prospected.

The rapid development of electric vehicles and large-scale energy storage systems have created a huge demand for high energy density and power density lithium-ion batteries in the market. Because of the advantages such as high voltage(4.7 V vs. Li/Li⁺), high energy density and power density, abundant resources and low cost, LiNi_0.5Mn_1.5O₄ is considered as one of the most promising lithium-ion battery cathode materials. However, the severe undesirable side reactions between LiNi_0.5Mn_1.5O₄ and electrolyte at elevated temperature leads to worse cycling performance, which limits its commercial application. Therefore, improving the high-temperature performance of LiNi_0.5Mn_1.5O₄ has become one of the research hotspots in the field of lithium-ion batteries. In this paper, the main achievements of recent researches on LiNi_0.5Mn_1.5O₄ materials are reviewed. Starting with the basic characteristics and existing challenges of LiNi_0.5Mn_1.5O₄, strategies such as ion doping, surface coating and surface doping are focused on improving the high-temperature performance. In addition, suggestions and prospects are put forward for subsequent research.

With the advantages of both lithium ion battery and supercapacitor, lithium ion capacitor battery has become a promising new energy storage system with its advantages of high energy density, high power density, long cycle life and fast charging and discharging. However, some key problems still exist, such as dynamic imbalance, less ideal energy density and poor cycling stability between battery electrode and capacitor electrode. The electrode material is an important part of the battery and seriously affects the overall electrochemical performance. To solve this problem effectively, a variety of new type of anode and cathode electrode materials should be developed in this field. Therefore, this paper introduces in detail the research progress and technical route of cathode(layered metal oxides, graphene composite anode and other novel cathode materials) and anode(transition metal oxides, carbon materials, lithium compounds and sulfides) materials for lithium ion capacitor batteries, and analyzes the existing problems. It is found that the properties of electrode materials can be improved by nano treatment, material coating and heteroatomic doping. At the same time, the future research direction of electrode materials is prospected, and new ideas and means are provided for the research of other chemical power sources.

In recent years, antibiotics have been detected in natural water bodies, soil, animals and plants and their excreta and have attracted widespread attention. This review summarizes and analyzes the studies published between 2011 and 2019 on the investigations of antibiotic residues in various environmental media in Zhejiang area. The results show that tetracyclines, sulfonamides, fluoroquinolones and chloramphenicols are the dominant antibiotics in the aquatic environment of Zhejiang. The concentration of antibiotics reaches 994 μg·L^-1 in the wastewater of farming livestock and poultry in Hangzhou, Jinhua, and Jiaxing, and it is as high as 66.62 mg·kg^-1 in the livestock and poultry manure, suggesting that the livestock and poultry breeding industry is one of the major sources of antibiotic pollution in the environment in Zhejiang. Furthermore, the concentration of antibiotics in the pharmaceutical wastewater reaches 5.7 mg·L^-1. It is noted that antibiotics are still detected in the effluents of wastewater treatment plants, and their concentrations could reach 88 μg·L^-1. The treated wastewaters are directly discharged into natural water. Residual antibiotics in the aquaculture areas could also enter the surface water directly without treatment. The concentration of antibiotics in the surface water of Zhejiang is 508.7ng·L^-1, but for most of the basin, the concentration is less than 100 ng·L^-1. Until now no antibiotics have been detected in the drinking water sources in Zhejiang such as Qiandao Lake, Lishui Shitang Reservoir, Quzhou Jiangshan Wanyao Reservoir and Tiaoxi River. However, in Zhoushan, the concentration of antibiotics in drinking water sources has reached 55 ng·L^-1. Although the levels of the antibiotic residues in the surface water are relatively low, their impacts should not be underestimated. These water bodies serve as water sources for aquaculture, livestock and poultry, and farmland irrigation, therefore the antibiotics residues could get back into livestock, poultry and crops, and potentially cause food contamination. It is thus recommended that future research could focus on continuous and comprehensive monitoring of antibiotic residues in the environment in Zhejiang, the fate and transformation of antibiotics due to the unique environmental factors and industrial structures of the region, and their potential adverse effect on ecological systems and human health.

Advanced oxidation processes(AOPs) based on sulfate radical(SO₄^.-) have attracted more and more attention due to their high degradation ability and adaptability to new types of organic pollutants. Compared with hydroxyl radical(·OH), SO₄^.- has better selectivity, higher reduction potential, longer half-life, wider pH range and lower cost, so it can degrade pollutants more effectively. SO₄^.- can be produced by persulfate(PS) such as peroxymonosulfate(PMS), peroxydisulfate(PDS), etc. which are activated by thermal, mechanochemical, transition metal, carbonaceous materials, alkali, ultraviolet(UV), electrochemical methods, etc. Advantages and disadvantages of different activation methods and the research progress of their applications in the degradation of organic pollutants are analyzed. Three degradation mechanisms(addition, hydrogen abstraction and direct electron transfer) of pollutants with different functional groups by SO₄^.- are summarized. The degradation pathways, degradation products, and research progress of persistent organic pollutants(POPs), “pseudo-persistent organic pollutants”, i.e. pharmaceuticals and personal care products(PPCPs), and organic dyes by SO₄^.- are reviewed. Moreover, future research directions of this technique are prospected.

Solid-state electroanalytical chemistry(SSEAC) is a method to analyze the information of solid materials by electrochemical methods, especially for the analysis of element composition, phase composition and redox state of solid materials. The SSEAC technology has been successfully applied to obtain the electrochemical information of natural pigments, plants, minerals and cultural relics with qualitative and quantitative analysis. SSEAC-based plant analysis is a cross-analysis technique emerging between electroanalytical chemistry and phytochemistry in recent years. SSEAC can provide a new understanding of the interspecific relationship, variation, differentiation and adaptation of species, which has a very intuitive practical value in the identification of medicinal materials, food safety and crop quality control. This article reviews the work of SSEAC technology in plant identification, plant phylogeny and plant physiological monitoring in recent years. This review also summarizes the challenges of SSEAC technology in plant analysis as well as its prospects in future development.

Inner filter effect(IFE) refers to the phenomenon that the absorber absorbs the excitation and/or emission light of the fluorophore, resulting in the fluorescence quenching of the fluorophore. Compared with fluorescence resonance energy transfer(FRET) or other techniques, IFE avoids cumbersome labeling processes, and has the advantages of high sensitivity, strong selectivity, simple and flexible operation. The IFE-based fluorescent approach has broad application foreground in the field of environmental monitoring. The absorber and the fluorophore are the two main components of the IFE-based sensing system. The optical properties and the spectral overlap of the two directly affect the quenching efficiency of the IFE-based sensing system. There are relatively limited choices of materials for the absorber and the fluorophore. Discovering new nanomaterials and exploring suitable absorber/fluorophore pair are very helpful to improve the quenching efficiency of IFE and enhance the detection performance of the IFE-based fluorescent approach. In this review, we mainly focus on the recent progress of IFE researches for environmental monitoring, including the detection of heavy metal ions, anions and small molecular environmental pollutants. The important effects of nanomaterials in the IFE-based sensing system are analyzed. Finally, the challenges and future developments of the IFE-based fluorescent approach are discussed.