Latest ArticlesGrain boundary (GB), as a kind of lattice defect, widely exists in two-dimensional transition metal dichalcogenides (2D TMDs), which has complex and diverse influences on the physical/chemical properties of 2D TMDs. GBs are universally considered to be a double-edged sword, although some electrical and mechanical properties of 2D TMDs would be adversely affected leading to the reduced overall quality, certain structure-oriented applications could be realized based on its unique properties. In this review, we first detailed the atomic structure characteristics of GBs and the corresponding techniques, then we systematically summarized the methods of introducing GBs into 2D TMDs. Next, we expounded unique electrical, mechanical, and chemical properties of the GBs in 2D TMDs and clarified its internal relationship with the atomic structure. Moreover, the application of GB structure in hydrogen evolution reaction (HER) is also discussed. In the end, we make a conclusion and put forward outlooks, hoping to further promote the basic research of GB and boost the wide application of 2D TMDs.
Rhodium(Ⅲ)-catalyzed CH couplings of arenes with alkenes are among the most powerful methods for CC bond formation. For these transformations, subtle manipulation of ancillary ligands can lead to dramatic changes in reactivity and selectivity. However, detailed mechanistic studies concerning the ligand effects are rare. In this study, we investigated the origin of ligand-controlled product-selectivity in rhodium(Ⅲ)-catalyzed CH couplings of arenes with alkenes, using a series of well-defined [CpXRhⅢ] complexes that feature electronically or sterically distinct CpX (Cp (η5-C5H5), CpCF3 (η5-C5Me4CF3) and Cp* (η5-C5Me5)) ligands. A combination of experimental and theoretical investigations showed that (i) rhodium hydride species containing the electron rich Cp* ligand can undergo reinsertion of the alkene, thereby allowing rhodium-walking, (ii) rhodium hydride species involving the electron-deficient Cp or CpCF3 ligands prefer reductive elimination rather than alkene insertion. These findings offer valuable insights on future rational catalyst design for selective arene–alkene cross coupling reactions.
Metal–organic framework (MOF) is a periodic sexual network structure with large surface area and high porosity, which is assembled by inorganic nodes and organic ligands through coordinate covalent bond. MOFs have the advantages of controllable pore size and shape, large specific surface area, easy modification and more active sites. In addition, MOF based nanoenzymes display excellent enzyme catalytic activity due to their special structure and multiple exposed metal active sites, controlling the production of reactive oxygen species (ROS) in cells or the body, and thus regulating the polarization of macrophage. This article reviews the mechanism of MOF material regulating macrophage polarization and the function of macrophages with different phenotypes. By utilizing the excellent properties of MOFs and the advantages of combining them with bioactive materials, we have discovered their excellent applications in the treatment of inflammatory diseases. Finally, we discussed the current challenges and prospects faced by MOF based composite materials. We expect that the research in this developing field will play a more important role in combating inflammatory diseases in the field of nanomedicine.
Targeted construction of new covalent organic frameworks (COFs) with specific purposes and rationalities to build colorimetric assay platform for environmental pollutant monitoring have attracted increasing interest. However, it is still challenging due to lack of available coordination sites inside COFs pores and only a slight bonding ability for anchoring metal. In this work, a two-dimensional (2D) COFs (termed as Tz-COF) with high crystallinity, excellent chemical stability, and abundant sulfur coordination in its skeletons was synthesized and used for the confined growth of Au NPs. It was found that the Au NPs showed significant dispersibility for the support of Tz-COF. The proposed Tz-COF@Au NPs possessed outstanding Hg2+-activated peroxidase-like activity benefited from physicochemical properties of gold amalgam and synergistic effect between COFs and Au NPs to oxidize chromogenic substrate. Based on highly efficient activity and distinctive color evolution, the strategy for detecting Hg2+ was developed and successfully applied to determine the content of Hg2+ in real environmental samples. This work manifests that a potential strategy to establish a colorimetric assay platform for environmental pollutant monitoring based on the targeted manufacturing of novel COFs with specific functions.
Commercial V2O5-based catalysts have been successfully applied in NH3 selective catalytic reduction (NH3-SCR) of NOx from power stations, but their poor alkali-resistance restrains the wider application in nonelectrical industries. In this study, NOx reduction against alkali poisoning over V2O5/TiO2 is greatly improved via Ce(SO4)2 modification. It has been originally demonstrated that Ce4+–SO42− pair sites play crucial roles in improving NOx reduction against alkali poisoning over V2O5/TiO2 catalysts. The strong interaction between V species and Ce sites of Ce4+–SO42− pairs triggers the reaction between NH4+species and gaseous NO via Eley-Rideal (E-R) reaction pathway. After K-poisoning, the SO42− sites of Ce4+–SO42− pairs as protective sites strongly bond with K and thus maintain the high reaction efficiency via the E-R reaction pathway. This work demonstrates an effective strategy to enhance NOx reduction against alkali poisoning over catalysts via constructing Ce4+–SO42− pair sites, contributing to developing alkali-resistant SCR catalysts for practical application in nonelectrical industries.
In the face of multiple challenges brought by the changes of global climate and environment, developing clean energy and updating green energy storage equipment are important ways to achieve carbon peak and carbon neutrality. Aqueous batteries have become a research hotspot due to their advantages of using the multivalent charge carrier, high ionic conductivity, environmental friendliness and cost effectiveness. In this work, the Cu2Se@C (Cu2Se coated on carbon clothes) thin film with a three-dimensional braided structure is fabricated by a simple electrochemical deposition method for Cu2+ storage for the first time. Compared with the commercial Cu2Se powder, the well-designed Cu2Se@C film shows enhanced specific capacity (640 mAh/g at 0.5 A/g) and rate performance (542 mAh/g at 5 A/g) as well as superior cycling stability (82.7% capacity retention after 1000 cycles at 1 A/g). The Cu2+ storage mechanism of the Cu2Se@C electrode is based on a reversible phase transition process of Cu2Se ↔ Cu2-xSe ↔ CuSe ↔ CuSe2. In kinetic characteristic analysis, the Cu2Se@C electrode demonstrates faster Cu2+ diffusion in discharge process than charge process resulting from the phase transition and the variation of interplanar spacing. This work highlights a facile one-piece design strategy and opens a new gateway for the exploration of advanced aqueous energy storage systems.
Covalent adaptable networks (CANs), which share the properties of both thermosets and thermoplastics at the same time, are desirable for many applications. Introducing bulky substituents is a feasible way to design dynamic covalent bonds for constructing CANs, as evidenced by the successful implementation in CANs based on hindered urea bonds (HUBs). However, the dynamicity induced by introducing bulky substituents always come with low bond energy, resulting in low mechanical strength and poor stability of the CANs. Herein, we designed a novel hindered urethane bond, which is weak in thermodynamic (Keq = 1701.23 L/mol at 25 ℃) and inert in kinetic at low temperature, but stable in thermodynamic (Keq = 1.54 × 104 L/mol at 100 ℃) and active in kinetic at high temperature (k-1 = 0.105 h−1 at 80 ℃ and 0.315 h−1 at 120 ℃). As a result, the polyurethane based on it exhibits high mechanical properties (with Youngs' modulus of 1011 ± 29 MPa and flexible modulus reached 1833 ± 50 MPa) and excellent reversibility (can be reprocessed at 60 ℃ under 100 kPa in 30 min and completely healed at 40 ℃ in 10 min). Moreover, unlike to many CANs based on hindered urea bonds, our dynamic polyurethanes are highly stable in humid environment or even water solutions due to the slow hydrolysis kinetics. Such high-performance dynamic polyurethane polymers are attractive for many applications.
As key biomarkers, amyloid-β (Aβ) plaques are frequently used to diagnose Alzheimer's disease (AD). Although fluorescence imaging has proven to be effective in detecting these plaques, the gold standard probe thioflavin T (ThT), used for Aβ aggregates, cannot be applied in vivo owing to its invasive nature. Therefore, the development of novel fluorescent probes capable of identifying Aβ plaques in situ is necessary. Based on the ThT structure, two π-conjugated heterocyclic D-π-A probes were designed bearing the hydroxytricyanopyrrole acceptor and N,N-dimethylaminophenyl donor. These probes exhibited red to near-infrared fluorescence emission (λmax = 732 nm), large Stokes shifts (>100 nm), exceptional signal-to-noise ratio, rapid response (<30 s), and high binding affinity (NT-HTCP = 33.32 nmol/L; NF-HTCP = 53.35 nmol/L) for Aβ aggregates. As the best candidate, NT-HTCP was used for in situ imaging of Aβ plaques in AD mouse models. Furthermore, in vivo research demonstrated that NT-HTCP could cross the blood–brain barrier and continue imaging the Aβ plaques with a good signal-to-noise ratio. Additionally, the outcomes of the docking computations helped guide the development of the Aβ probes. This study expands the family of N,N-dimethylaminophenyl-based Aβ-sensitive fluorophores, with NT-HTCP emerging as a highly promising imaging agent.
Mechanochromophores based on bichromic molecular switches, such as bis-naphthopyanes, allow multimodal mechanochromic behavior beyond the typical binary response from single chromophores, which is important for distinguishing between multiple stress states through discrete changes in color. Spontaneously generated persistent and distinguishable multi-colors from activated bis-naphthopyanes remain challenging. And the versatility of bis-mechanophore design for advanced optical molecular systems and the fundamental insights into the corresponding mechano-reactivity are not enough. Here, we identify a dihydroanthracene bridged bis-naphthopyrans as a multimodal mechanochromophore in polymers. Bridging two pyrans with the sterically constrained dihydroanthracene is helpful to control the steric effect for the favorable formation of a distinctly appreciable bis-merocyanine (bis-MC) product. By varying the length of the polymer chains, the force delivered to the mechanophore is modulated, resulting in a gradient change in the relative distribution of two distinctly colored MC products and a multicolor mechanochromism. Mechanical activation of this bis-naphthopyanes proceeds via a mechanistically distinct pathway compared to the photochemical process. In addition, the bulk films can also achieve pronounced color changes when subjected to mechanical force. This study thus further expands the molecular diversity of mechanochromophores and tune the multimodal switch properties of bis-naphthopyrans based polymers.
In September 2018, we proposed the cutting-edge concept of "Beyond Limits Manufacturing" (BLM). BLM technology is based on the three-dimensional inner engraving or precise outer engraving of ultra-fast laser, to invent micro/nano scale flow chips or devices, which makes it possible for the microform, integration, economy, safety, high efficiency, green and intelligence of research, development and manufacturing process, so as to realize transformational manufacturing in the era of Industry 4.0. In this paper, we reviewed the representative results we made in the field of micro/nano flow chemistry during the implementation of the BLM major project (December 2019 to August 2023), and discussed its application prospects in micro/nano flow chemistry.
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