In recent years, the rapidly growing attention on MXenes makes the material a rising star in the 2D materials family. Although most researchers' interests are still focused on the properties of bare ...MXenes, little attention has been paid to the surface chemistry of MXenes and MXene‐based nanocomposites. To this end, this Review offers a comprehensive discussion on surface modified MXene‐based nanocomposites for energy conversion and storage (ECS) applications. Based on the structure and reaction mechanism, the related synthesis methods toward MXenes are briefly summarized. After the discussion of existing surface modification techniques, the surface modified MXene‐based nanocomposites and their inherent chemical principles are presented. Finally, the application of these surface modified nanocomposites for supercapacitors (SCs), lithium/sodium–ion batteries (LIBs/SIBs), and electrocatalytic water splitting is discussed. The challenges and prospects of MXene‐based nanocomposites for future ECS applications are also presented.
Recently, MXenes have gained increasing attention in the field of energy conversion and storage (ECS). Meanwhile, the unique surface chemistry of MXenes endows them with great potential in the construction of 2D based nanocomposites. To this end, the present work offers a comprehensive summary of surface modified MXene‐based nanocomposites for ECS applications.
Herein, the authors present the development of novel 0D–2D nanohybrids consisting of a nickel‐based bimetal phosphorus trisulfide (Ni1−xFexPS3) nanomosaic that decorates on the surface of MXene ...nanosheets (denoted as NFPS@MXene). The nanohybrids are obtained through a facile self‐assemble process of transition metal layered double hydroxide (TMLDH) on MXene surface; followed by a low temperature in situ solid‐state reaction step. By tuning the Ni:Fe ratio, the as‐synthesized NFPS@MXene nanohybrids exhibit excellent activities when tested as electrocatalysts for overall water splitting. Particularly, with the initial Ni:Fe ratio of 7:3, the obtained Ni0.7Fe0.3PS3@MXene nanohybrid reveals low overpotential (282 mV) and Tafel slope (36.5 mV dec−1) for oxygen evolution reaction (OER) in 1 m KOH solution. Meanwhile, the Ni0.9Fe0.1PS3@MXene shows low overpotential (196 mV) for the hydrogen evolution reaction (HER) in 1 m KOH solution. When integrated for overall water splitting, the Ni0.7Fe0.3PS3@MXene || Ni0.9Fe0.1PS3@MXene couple shows a low onset potential of 1.42 V and needs only 1.65 V to reach a current density of 10 mA cm−2, which is better than the all noble metal IrO2 || Pt/C electrocatalyst (1.71 mV@10 mA cm−2). Given the chemical versatility of Ni1−xFexPS3 and the convenient self‐assemble process, the nanohybrids demonstrated in this work are promising for energy conversion applications.
Novel 0D–2D nanohybrids consisting of a nickel‐based bimetal phosphorus trisulfide (Ni1−xFexPS3) nanomosaic that decorates the surface of MXene nanosheets are obtained through a facile self‐assembly process. The Ni0.7Fe0.3PS3@MXene reveals low overpotential (282 mV) and Tafel slope (36.5 mV dec−1) for oxygen evolution reaction (OER) and the Ni0.7Fe0.3PS3@MXene || Ni0.9Fe0.1PS3@MXene couple shows good overall water splitting performance.
To investigate the biomechanical effects of the lumbar posterior complex on the adjacent segments after posterior lumbar interbody fusion (PLIF) surgeries.
A finite element model of the L1-S1 segment ...was modified to simulate PLIF with total laminectomy (PLIF-LAM) and PLIF with hemilaminectomy (PLIF-HEMI) procedures. The models were subjected to a 400N follower load with a 7.5-N.m moment of flexion, extension, torsion, and lateral bending. The range of motion (ROM), intradiscal pressure (IDP), and ligament force were compared.
In Flexion, the ROM, IDP and ligament force of posterior longitudinal ligament, intertransverse ligament, and capsular ligament remarkably increased at the proximal adjacent segment in the PLIF-LAM model, and slightly increased in the PLIF-HEMI model. There was almost no difference for the ROM, IDP and ligament force at L5-S1 level between the two PLIF models although the ligament forces of ligamenta flava remarkably increased compared with the intact lumbar spine (INT) model. For the other loading conditions, these two models almost showed no difference in ROM, IDP and ligament force on the adjacent discs.
Preserved posterior complex acts as the posterior tension band during PLIF surgery and results in less ROM, IDP and ligament forces on the proximal adjacent segment in flexion. Preserving the posterior complex during decompression can be effective on preventing adjacent segment degeneration (ASD) following PLIF surgeries.
Mo‐Ni alloy‐based electrocatalysts are regarded as promising candidates for the hydrogen evolution reaction (HER), despite their vulnerable stability in alkaline solution that hampers further ...application. Herein, Mo2TiC2Tx MXene, is employed as a support for MoNi4 alloy nanocrystals (NCs) to fabricate a unique nanoflower‐like MoNi4–MXn electrocatalyst. A remarkably strong built‐in electric field is established at the interface of two components, which facilitates the electron transfer from Mo2TiC2Tx to MoNi4. Due to the accumulation of electrons at the MoNi4 sites, the adsorption of the catalytic intermediates and ionic species on MoNi4 is affected consequently. As a result, the MoNi4–MX10 nanohybrid exhibits the lowest overpotential, even lower than 10% Pt/C catalyst at the current density of 10 mA cm−2 in 1 m KOH solution (122.19 vs 129.07 mV, respectively). Furthermore, a lower Tafel slope of 55.88 mV dec−1 is reported as compared to that of the 10% Pt/C (65.64 mV dec−1). Additionally, the MoNi4–MX10 catalyst also displays extraordinary chemical stability in alkaline solution, with an activity loss of only 0.15% per hour over 300 h of operation. This reflects the great potential of using MXene‐based interfacial engineering for the synthesis of a highly efficient and stable electrocatalyst.
The strong built‐in electric field at the interface of the MoNi4–MXn heterostructure facilitates electron transfer and adsorption of intermedia species. Therefore, the nanohybrid shows the lowest overpotential of 122.19 mV at 10 mA cm−2 with Tafel slope of 55.88 mV dec−1 for hydrogen evolution reaction (HER), meanwhile exhibiting excellent stability over 300 h in 1 m KOH solution.
Sodium (Na) metal as an anode is one of the ultimate choices for the high‐energy rechargeable batteries in virtue of its intrinsic high theoretical capacity (1166 mAh g−1) and low redox potential ...(−2.71V vs standard hydrogen electrode (SHE)), as well as its low cost and broad sources. Nevertheless, the dendrite‐related hazards seriously block its practical application. Na dendrite formation mainly emanates from the uncontrolled Na deposition behavior. Therefore, it seems particularly important to employ appropriate strategies towards the homogeneous deposition of Na for the dendrite‐free metal anode. In this review, the challenge of regulating Na homogeneous deposition for dendrite‐free Na anodes is first discussed. Then, recent advances in the strategies of regulating the Na uniform deposition are summarized, including adjusting Na+ flux near the solid‐liquid interface and improving sodiophilicity on the biphase interface. Lastly, perspectives on further research and important factors toward the practical application of high‐energy‐density Na metal batteries are emphasized in detail.
The recent advances in the regulation of uniform Na deposition are summarized and discussed in detail from two aspects: regulating Na+ flux near the solid–liquid interface and improving sodiophilicity on the biphase interface, which can provide guidance for the realization of high‐performance Na metal batteries.
BN‐heteroarenes, which employ both boron and nitrogen in aromatic hydrocarbons, have gained great attention in the fields of organic chemistry and materials science. Nevertheless, the extensive ...studies on BN‐heteroarenes are largely limited to 1,2‐azaborine‐based compounds with B–N covalent bonds, whereas 1,3‐ and 1,4‐BN‐heteroarenes are relatively rare due to their greater challenge in the synthesis. Recently, significant progresses have been achieved in the synthesis and applications of BN‐heteroarenes featuring 1,4‐azaborines, especially driven by their significant potential as multiresonant thermally activated delayed fluorescence (MR‐TADF) materials. Therefore, it is timely to review these advances from the chemistry perspective. This review summarizes the synthetic methods and recent achievements of 1,4‐azaborine‐based BN‐heteroarenes and discusses their unique properties and potential applications of this emerging class of materials, highlighting the value of 1,4‐BN‐heteroarenes beyond MR‐TADF materials. It is hoped that this review would stimulate the conversation and cooperation between chemists who are interested in azaborine chemistry and materials scientists working in the fields of organic optoelectronics, metal catalysis, and carbon‐based nanoscience etc.
Boron and nitrogen (BN)‐heteroarenes have gained great attention in organic chemistry and materials science. Recently, significant progresses have been achieved in the synthesis and applications of BN‐heteroarenes featuring 1,4‐azaborine moieties. This review summarizes the synthetic methods and recent achievements of 1,4‐azaborine‐based BN‐heteroarenes, and discusses their unique properties and potential applications, in order to stimulate the synergistic development of azaborine chemistry and materials research.
A typical polyanionic based material Na3V2(PO4)2O2F (Na3VPO2F) attracts much interest as a cathode for large‐scale sodium‐ion batteries in consideration of its stable structure and remarkable energy ...density. Nevertheless, the large coulombic attraction and repulsion suffered by the mobile Na+ from structural anions and surrounding Na+, respectively, result in a torpid reaction kinetics and inferior rate capability. Herein, Br−‐doped and Na+ vacancy preinstalled Na3−yVPO2−xBrxF is prepared to dilute the charges on and inside the Na+ transportation tunnel. In virtue of density functional theory analysis, Na3−yVPO2−xBrxF reveals a reduction in the bandgap and an increase in electronic conductivity. Meanwhile, the almost electrostatically shielded tunnel in Na3−yVPO2−xBrxF alleviates the coulombic hindrance imposed on Na+ during its (de)intercalation, which demonstrates a Na+ diffusivity about five times higher than that of Na3VPO2F. Consequently, the Na3−yVPO2−xBrxF cathode shows a superior rate capacity of 77.7 mAh g−1 under 50 C and great cycling property corresponding to a high capacity retention of 94.4% over 800 cycles at 10 C. The assembled Na3−yVPO2−xBrxF//hard‐carbon sodium‐ion full‐cell presents excellent specific energy/power (226 Wh kg−1@15424.2 W kg−1) as well as outstanding long‐term cyclic stability over 1000 cycles at 5 C.
Br‐doped and Na+‐vacancy‐preinstalled Na3V2(PO4)2O2F (Na3−yVPO2−xBrxF) is successfully prepared through a one‐step chemical vapor replacing (CVR) process. In virtue of density functional theory analysis, Na3−yVPO2−xBrxF reveals an increase in electronic conductivity with an almost electrostatically shielded tunnel for fast Na+ diffusion. Therefore, the Na3−yVPO2−xBrxF cathode shows superior Na+ storage capability in both half and full cells.
In this study, two-dimensional (2D) and three-dimensional (3D) freestanding reduced graphene oxide-supported Cu2O composites (Cu2O-rGO) were synthesized via simple and cost-efficient hydrothermal and ...filtration strategies. The structural characterizations clearly showed that highly porous 3D graphene aerogel-supported Cu2O microcrystals (3D Cu2O-GA) have been successfully synthesized, and the Cu2O microcrystals are uniformly assembled in the 3D GA. Meanwhile, paper-like 2D reduced graphene oxide-supported Cu2O nanocrystals (2D Cu2O-rGO-P) have also been prepared by a filtration process. It was found that the products prepared from different precursors and methods exhibited different sensing performances for H2O2 detection. The electrochemical measurements demonstrated that the 3D Cu2O-GA has high electrocatalytic activity for the H2O2 reduction and excellent sensing performance for the electrochemical detection of H2O2 with a detection limit of 0.37 μM and a linear detection range from 1.0 μM to 1.47 mM. Meanwhile, the 2D Cu2O-rGO-P structure also showed good electrochemical sensing performance toward H2O2 detection with a much wider linear response over the concentration range from 5.0 μM to 10.56 mM. Compared to the previously reported sensing materials, the as-obtained 2D and 3D Cu2O-rGO materials exhibited higher electrochemical sensing properties toward the detection of H2O2 with high sensitivity and selectivity. The 2D and 3D Cu2O-rGO composites also exhibited high sensing performance for the real-time detection of H2O2 in human serum. The present study indicates that 2D and 3D graphene-Cu2O composites have promising applications in the fabrication of nonenzymatic electrochemical sensing devices.
Microplastics (MPs) are ubiquitous in the environment and more abundant in the marine environment. Consequently, increasing focus has been put on MPs in oceans and seas, while little importance has ...been attached to their presence in freshwaters and soils. Therefore, this paper aimed to provide a comprehensive review of the occurrence, analysis and ecotoxicology of MPs. The abundance and distribution of MPs in several typical freshwater systems of China were summarized. It suggested that the surface water of Poyang Lake contained the highest concentration of 34 items/L MPs among all the 8 freshwater systems, and the content of MPs in sediments were higher than that of the surface water. Net-based zooplankton sampling methods are the most frequently utilized sampling methods for MPs, and density separation, elutriation and digestion are three major pretreatment methods. Fourier transform infrared spectroscopy, Raman spectroscopy and pyrolysis-gas chromatography coupled to mass spectrometry are often used to identify the polymer types of MPs. Besides, MPs might damage the digestive tract of various organisms and negatively inhibit their growth, feeding and reproduction. The ways of human exposure to MPs are by ingestion, inhalation and dermal exposure, digestive and respiratory system might be adversely influenced. However, potential health risks of MPs to humans are remained insufficiently researched. Overall, by showing the presence of MPs in freshwaters and soils as well as possible ecotoxicological effects on the environment and humans, this paper provided a framework for future research in this field.
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•Occurrence and distribution of microplastics in freshwater systems were discussed.•Sampling and analytical methods of microplastics in soils and waters were reviewed.•Ecological effects of microplastics on organisms and humans were summarized.•Research gaps were revealed and future research recommendations were proposed.
Manganese dioxide (MnO2) has been widely used in the field of energy storage due to its high specific capacitance, low cost, natural abundance, and being environmentally friendly. However, suffering ...from poor electrical conductivity and high dissolvability, the performance of MnO2 can no longer meet the needs of rapidly growing technological development, especially for the application as electrode material in metal‐ion batteries and supercapacitors. In this review, recent studies on the development of binary or multiple MnO2‐based composites with conductive components for energy storage are summarized. Firstly, general preparing methods for MnO2‐based composites are introduced. Subsequently, the binary and multiple MnO2‐based composites with carbon, conducting polymer, and other conductive materials are discussed respectively. The improvement in their performance is summarized as well. Finally, perspectives on the practical applications of MnO2‐based composites are presented.
The fabrication of binary or multi‐component MnO2‐based composites is summarized in this review, their applications in metal‐ion batteries and supercapacitors, as well as the effects on electrochemical performance, are discussed. The contribution of each component to the final performance is also illustrated.
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