Rapid room-temperature synthesis of a porphyrinic MOF for encapsulating metal nanoparticles

While metal nanoparticles(NPs)have shown great promising applications as heterogeneous catalysts,their agglomeration caused by thermodynamic instability is detrimental to the catalytic performance.To tackle this hurdle,we successfully prepared a functional and stable porphyrinic metal-organic framework(MOF),PCN-224-RT,as a host for encapsulating metal nanoparticles by direct stirring at room temperature.As a result,Pt@PCN-224-RT composites with well-dispersed Pt NPs can be constructed by introducing pre-synthesized Pt NPs into the precursor solution of PCN-224-RT.Of note,the rapid and simple stirring method in this work is more in line with the requirements of environmental friendly and industrialization compared with traditional solvothermal methods.     

Two-dimensional polymer nanosheets for efficient energy storage and conversion

As a promising graphene analogue, two-dimensional (2D) polymer nanosheets with unique 2D features, diversified topological structures and as well as tunable electronic properties, have received extensive attention in recent years. Here in this review, we summarized the recent research progress in the preparation methods of 2D polymer nanosheets, mainly including interfacial polymerization and solution polymerization. We also discussed the recent research advancements of 2D polymer nanosheets in the fields of energy storage and conversion applications, such as batteries, supercapacitors, electrocatalysis and photocatalysis. Finally, on the basis of their current development, we put forward the existing challenges and some personal perspectives.

     

Polymersome formation by solvent annealing-induced structural reengineering under 3D soft confinement

A solvent annealing-induced structural reengineering approach is exploited to fabricate polymersomes from block copolymers that are hard to form vesicles through the traditional solution self-assembly route. More specifically, polystyrene-b-poly(4-vinyl pyridine) (PS-b-P4VP) particles with sphere-within-sphere structure (SS particles) are prepared by three-dimensional (3D) soft-confined assembly through emulsion-solvent evaporation, followed by 3D soft-confined solvent annealing upon the SS particles in aqueous dispersions for structural engineering. A water-miscible solvent (e.g., THF) is employed for annealing, which results in dramatic transitions of the assemblies, e.g., from SS particles to polymersomes. This approach works for PS-b-P4VP in a wide range of block ratios. Moreover, this method enables effective encapsulation/loading of cargoes such as fluorescent dyes and metal nanoparticles, which offers a new route to prepare polymersomes that could be applied for cargo release, diagnostic imaging, and nanoreactor, etc.

     

Synthesis of magnetic two-dimensional materials by chemical vapor deposition

The development of magnetic two-dimensional (2D) materials in its infancy has generated an enormous amount of attention as it offers an ideal platform for the exploration of magnetic properties down to the 2D limit, paving the way for spintronic devices. Due to the nonnegligible advantages including time efficiency and simplified process, the facile bottom-up chemical vapor deposition (CVD) is regarded as a robust method to fabricate ultrathin magnetic nanosheets. Recently, some ultrathin magnets possessing fascinating properties have been successfully synthesized via CVD. Here, the recent researches toward magnetic 2D materials grown by CVD are systematically summarized with special emphasis on the fabrication methods. Then, heteroatoms doping and phase transition induced in CVD growth to bring or tune the magnetic properties in 2D materials are discussed. Characterizations and applications of these magnetic materials are also discussed and reviewed. Finally, some perspectives in need of urgent attention regarding the development of CVD-grown magnetic 2D materials are proposed.

     

Functionalized graphene oxide nanosheets with unique three-in-one properties for efficient and tunable antibacterial applications

Developing antibiotics-independent antibacterial agents is of great importance since antibiotic therapy faces great challenges from drug resistance.Graphene oxide(GO)is a promising agent due to its natural antibacterial mechanisms,such as sharp edgemediated cutting effect.However,the antibacterial activity of GO is limited by its negative charge and low photothermal effect.Herein,the amino-functionalized GO nanosheets(AGO)with unique three-in-one properties were synthesized.Three essential properties(positive charge,strong photothermal effect,and natural cutting effect)were integrated into AGO.The positive charge(30 mV)rendered AGO a strong interaction force with model pathogen Streptococcus mutans(330 nN).The natural cutting effect of 100 ng·mL^-1AGO caused 27%loss of bacterial viability after incubation for 30 min.Most importantly,upon the near-infrared irradiation for just 5 min,the three-in-one properties of AGO caused 98%viability loss.In conclusion,the short irradiation period and the tunable antibacterial activity confer the three-in-one AGO a great potential for clinical use.     

Highly effective H2/D2 separation in a stable Cu-based metal-organic framework

A three-dimensional copper metal-organic framework with the rare chabazite(CHA)topology namely FJI-Y11 has been constructed with flexibly carboxylic ligand 5,5'-[(1,4-phenylenebis(methylene))bis(oxy)]diisophthalic acid(H₄L).FJI-Y11 exhibits high water stability with the pH range from 2 to 12 at temperature as high as 373 K.Importantly,FJI-Y11 also shows high efficiency of hydrogen isotope separation using dynamic column breakthrough experiments under atmospheric pressure at 77 K.Attributed to its excellent structural stability,FJI-Y11 possesses good regenerated performance and maintains high separation efficiency after three cycles of breakthrough experiments.     

Single metal atom decorated photocatalysts: Progress and challenges

Photocatalysis has attracted intense attention due to its potential to solve the energy resource problem and environmental issues.The single metal atom decorated photocatalysts as a rising star become more and more popular because of the unique advantages of superior catalytic activities and ultrahigh atom utilization efficiency.The key function of single metal atom catalysts in photocatalytic reactions is boosting surface redox reactions by utilizing photogenerated charges,and has been verified by various spectroscopic and microscopic techniques.Nevertheless,the activities of the single metal atoms highly depend on the binding environment in the host photocatalyst that affect the adsorption and activation of reactants as well as the reaction energy barrier.Herein,this mini review summarizes recent progress on single metal atom decorated photocatalysts,and discusses the roles of the single metal atom catalysts in different types of host photocatalysts including organic,carbon-based and inorganic materials.The remaining challenges and future perspectives on the stability and activities of single atom catalysts in photocatalytic processes are elaborated in the end.We believe that this mini review will provide valuable overview on synthetic methods of different single atom photocatalysts for researchers towards future development of highly efficient photocatalysts.     

Synthesis of wafer-scale graphdiyne/graphene heterostructure for scalable neuromorphic computing and artificial visual systems

Graphdiyne (GDY) is emerging as a promising material for various applications owing to its unique structure and fascinating properties. However, the application of GDY in electronics and optoelectronics are still in its infancy, primarily owing to the huge challenge in the synthesis of large-area and uniform GDY film for scalable applications. Here a modified van der Waals epitaxy strategy is proposed to synthesize wafer-scale GDY film with high uniformity and controllable thickness directly on graphene (Gr) surface, providing an ideal platform to construct large-scale GDY/Gr-based optoelectronic synapse array. Essential synaptic behaviors have been realized, and the linear and symmetric conductance-update characteristics facilitate the implementation of neuromorphic computing for image recognition with high accuracy and strong fault tolerance. Logic functions including “NAND” and “NOR” are integrated into the synapse which can be executed in an optical pathway. Moreover, a visible information sensing-memory-processing system is constructed to execute real-time image acquisition, in situ image memorization and distinction tasks, avoiding the time latency and energy consumption caused by data conversion and transmission in conventional visual systems. These results highlight the potential of GDY in applications of neuromorphic computing and artificial visual systems.

     

Corrosion formation and phase transformation of nickel-iron hydroxide nanosheets array for efficient water oxidation

Designing earth-abundant electrocatalysts with high performance towards water oxidation is highly decisive for the sustainable energy technologies. This study develops a facile natural corrosion approach to fabricate nickel-iron hydroxides for water oxidation. The resulted electrode demonstrates an outstanding activity and stability with an overpotential of 275 mV to deliver 10 mA·cm⁻². Experimental and theoretical results suggest the corrosion-induced formation of hydroxides and their transformation to oxyhydroxides would account for this excellent performance. This work not only provides an interesting corrosion approach for the fabrication of excellent water oxidation electrode, but also bridges traditional corrosion engineering and novel materials fabrication, which would offer some insights in the innovative principles for nanomaterials and energy technologies.

     

Mechanistic insight into gold nanorod transformation in nanoscale confinement of ZIF-8

Core-shell hybrid nanomaterials have shown new properties and functions that are not attainable by their single counterparts.Nanoscale confinement effect by porous inorganic shells in the hybrid nanostructures plays an important role for chemical transformation of the core nanoparticles.However,metal-organic frameworks(MOFs)have been rarely applied for understanding mechanical insight into such nanoscale phenomena in confinement,although MOFs would provide a variety of properties for the confining environment than other inorganic shells such as silica and zeolite.Here,we examine chemical transformation of a gold nanorod core enclosed by a zeolitic imidazolate framework(ZIF)through chemical etching and regrowth,followed by quantitative analysis in the core dimension and curvature.We find the nanorod core shows template-effective behavior in its morphological transformation.In the etching event,the nanorod core is spherically carved from its tips.The regrowth on the spherically etched core inside the ZIF gives rise toformation of a raspberry-like branched nanostructure in contrast to the growth of an octahedral shape in bulk condition.We attribute the shell-directed regrowth to void space generated at the interfaces between the etched core and the ZIF shell,intercrystalline gaps in mult-domain ZIF shells,and local structural deformation from the acidic reaction conditions.     

Recent advances in engineered nanomaterials for acute kidney injury theranostics

Acute kidney injury(AKI),has become the focus of increasing attention due to its high risk of death.The early diagnosis and treatment of AKI significantly reduce the risk of renal tissue damage and kidney dysfunction.However,the efficient early diagnosis and treatment approach for AKI remains a challenge.AKI screening via precise nanomaterial theranostics is a new alternative approach.This study summarizes the recent advances in functional nanomaterials in the early detection and treatment of AKI.The challenges and problems in the use of nanomaterials for AKI in clinical applications are also discussed.It is anticipated that highlighting these new advances will lay the foundation for further translational research on the promising application of nanomaterials for AKI.     

Developments in stability and passivation strategies for black phosphorus

Black phosphorus (BP), a promising two-dimensional layer material, has attracted increasing attention due to its high carrier mobility, thickness-dependent tunable bandgap, in-plane anisotropy, and other advantageous characteristics. Because of these excellent characteristics, BP has been considered for applications in optics, electronics, optoelectronics, sensors, and energy storage. However, early studies found that BP has high chemical activity due to the lone pair electrons of P atoms on the surface and edges, resulting in rapid degradation under ambient conditions and limiting many applications. Recently, these thorny issues have been alleviated through superior physical and chemical passivation techniques, and passivated BP can be used in various devices under ambient and water conditions with excellent performance over a long period. This review, highlights the critical problems addressed in solving the serious instability of BP in a harsh environment by effective passivation technology. These unique strategies can provide more researchers with a fundamental study of the fascinating properties of BP. Finally, we found that passivated BP not only showed good stability under ambient conditions but also exhibited excellent performance compared with the original BP. Therefore, it is anticipated that this overview can contribute to the application of BP.

     

Ambipolar two-dimensional bismuth nanostructures in junction with bismuth oxychloride

Despite the unique properties of bismuth(Bi),there is a lack of two-dimensional(2D)heterostructures between Bi and other functional 2D materials.Here,a coherent strategy is reported to simultaneously synthesize rhombohedral phase Bi nanoflakes and bismuth oxychloride(BiOCI)nanosheets.The delicate balance between several reactions is mediated mainly for the reduction and chlorination in the chemical vapor transport(CVT)process.The Bi-BiOCI lateral heterostructures have been constructed via the coalescence of the two different 2D nanostructures.The characteristics of ambipolar conducting Bi and insulator-like BiOCI are elaborated by scanning microwave impedance microscopy(sMIM).This work demonstrates a way to construct a 2D Bi nanostructure in junction with its oxyhalide.     

Surface active-site engineering in hierarchical PtNi nanocatalysts for efficient triiodide reduction reaction

Hierarchical Pt-alloys enriched with active sites are highly desirable for efficient catalysis, but their syntheses generally need time-consuming and elaborate annealing treatment at high temperature. We herein report a surface active-site engineering strategy for constructing the hierarchical PtNi nanocatalysts with an atomic Pt-skin layer (PtNi@Pt-SL) towards efficient triiodide reduction reaction (TRR) via an acid-dealloying approach. The facile acid-dealloying process promotes the formation of surface Pt active sites on the hierarchical Pt-alloys, and thus results in good catalytic performance towards TRR. Theoretical calculation reveals that the enhanced catalytic property stems from the moderate energy barriers for iodide atoms on the surface Pt active-sites. The surface active-site engineering strategy paves a new way for the design of active and durable electrocatalysts.

     

Basic science of water: Challenges and current status towards a molecular picture

Rapid developments in both fundamental science and modern technology that target water-related problems, including the physical nature of our planet and environment, the origin of life, energy production via water splitting, and water purification, all call for a molecular-level understanding of water. This invokes relentless efforts to further our understanding of the basic science of water. Current challenges to achieve a molecular picture of the peculiar properties and behavior of water are discussed herein, with a particular focus on the structure and dynamics of bulk and surface water, the molecular mechanisms of water wetting and splitting, application-oriented research on water decontamination and desalination, and the development of complementary techniques for probing water at the nanoscale.

     

Synthesis of graphene quantum dots for their supramolecular polymorphic architectures

How to regulate the supramolecular structures in the assembly of graphene quantum dots(GQDs)is still a great challenge to be overcome.Herein,the GQDs of 1-3 layers with high quality are synthesized from the new precursor m-trihydroxybenzene in a green method.More importantly,a strategy for designing the supramolecular structures of GQDs is demonstrated,and the novel supramolecular morphologies of GQDs have been constructed for the first time.Moreover,the supramolecular morphologies of GQDs can be well controlled by regulating the preparation conditions,and the formation mechanism of the branch-like supramolecular structure has been explained by the the diffusion-limited aggregation(DLA)model.This work not only develops a new precoursor to synthesize GQDs,but also opens up an effective route toform the polymorphic supermolecules,thus greatly facilitating their potential applications.     

Superhydrophobic,photo-sterilize,and reusable mask based on graphene nanosheet-embedded carbon (GNEC) film

The 2019 coronavirus disease(COVID-19)has affected more than 200 countries.Wearing masks can effectively cut off the virus spreading route since the coronavirus is mainly spreading by respiratory droplets.However,the common surgical masks cannot be reused,resulting in the increasing economic and resource consumption around the world.Herein,we report a superhydrophobic,photo-sterilize,and reusable mask based on graphene nanosheet-embedded carbon(GNEC)film,with high-density edges of standing structured graphene nanosheets.The GNEC mask exhibits an excellent hydrophobic ability(water contact angle:157.9°)and an outstanding filtration efficiency with 100%bacterial filtration efficiency(BFE).In addition,the GNEC mask shows the prominent photo-sterilize performance,heating up to 110℃quickly under the solar illumination.These high performances may facilitate the combat against the COVID-19 outbreaks,while the reusable masks help reducing the economic and resource consumption.     

Discovery of Zr-based metal-organic polygon: Unveiling new design opportunities in reticular chemistry

Metal-based secondary building unit and the shape of organic ligands are the two crucial factors for determining the final topology of metal-organic materials.A careful choice of organic and inorganic structural building units occasionally produces unexpected structures,facilitating deeper fundamental understanding of coordination-driven self-assembly behind metal-organic materials.Here,we have synthesized a triangular metal-organic polygon(MOT-1),assembled from bulky tetramethyl terephthalate and Zr-based secondary building unit.Surprisingly,the Zr-based secondary building unit serves as an unusual ditopic Zr-connector,toform metal-organic polygon MOT-1,proven to be a good candidate for water adsorption with recyclability.This study highlights the interplay of the geometrically frustrated ligand and secondary building unit in controlling the connectivity of metal-organic polygon.Such a strategy can be further used to unveil a new class of metal-organic materials.     

How defects influence the photoluminescence of TMDCs

Two-dimensional(2D)transition metal dichalcogenide(TMDC)monolayers,a class of ultrathin materials with a direct bandgap and high exciton binding energies,provide an ideal platform to study the photoluminescence(PL)of light-emitting devices.Atomically thin TMDCs usually contain various defects,which enrich the lattice structure and give rise to many intriguing properties.As the influences of defects can be either detrimental or beneficial,a comprehensive understanding of the internal mechanisms underlying defect behaviour is required for PL tailoring.Herein,recent advances in the defect influences on PL emission are summarized and discussed.Fundamental mechanisms are the focus of this review,such as radiative/nonradiative recombination kinetics and band structure modification.Both challenges and opportunities are present in the field of defect manipulation,and the exploration of mechanisms is expected tofacilitate the applications of 2D TMDCs in the future.     

Pulsed laser reshaping and fragmentation of upconversion nanoparticles — from hexagonal prisms to 1D nanorods through “Medusa”-like structures

One dimensional (1D) nanostructures attract considerable attention, enabling a broad application owing to their unique properties. However, the precise mechanism of 1D morphology attainment remains a matter of debate. In this study, ultrafast picosecond (ps) laser-induced treatment on upconversion nanoparticles (UCNPs) is offered as a tool for 1D-nanostructures formation. Fragmentation, reshaping through recrystallization process and bioadaptation of initially hydrophobic (β-Na_1.5Y_1.5F₆: Yb³⁺, Tm³⁺/β-Na_1.5Y_1.5F₆) core/shell nanoparticles by means of one-step laser treatment in water are demonstrated. “True” 1D nanostructures through “Medusa”-like structures can be obtained, maintaining anti-Stokes luminescence functionalities. A matter of the one-dimensional UCNPs based on direction of energy migration processes is debated. The proposed laser treatment approach is suitable for fast UCNP surface modification and nano-to-nano transformation, that open unique opportunities to expand UCNP applications in industry and biomedicine.