MOF-derived Co9S8/MoS2 embedded in tri-doped carbon hybrids for efficient electrocatalytic hydrogen evolution

Metal-organic framework(MOF)derived hybrid materials have been developed as an efficient non-noblemetal electrocatalysts for clean energy conversion systems.In this work,a Co-based MOF containing nitrogen and oxygen heteroatoms(Co-NOMOF)mixed with the thiomolybdate[Mo3S(13)]^2- nanoclusters was used to prepare the N,S,O-doped carbon encapsulating Co9S8 and MoS2(Co9S8/MoS2@NSOC)nanocomposite by one-step pyrolysis.The Co9S8/MoS2@NSOC nanocomposite exhibited remarkable catalytic performance for hydrogen evolution reaction(HER)with overpotential of 194 and 233 mV in 1 M KOH and 0.5 M H2SO4 solution under 10 mA cm^-2,respectively,which was ascribed to the multiheteroatom-doped hierarchical porous carbon matrix and the synergistic effect of intrinsic activity of Co9S8 and MoS2.This work provides new opportunity for developing highly efficient non-precious metal electrochemical catalysts.

Interface-engineered MoS_(2)/CoS/NF bifunctional catalysts for highly-efficient water electrolysis

The utilization of non-noble metal catalysts with robust and highly efficient electrocatalytic activity for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)are extremely important for the large-scale implementation of renewable energy devices.Integration of bifunctional electrocatalysts on both anode and cathode electrodes remains a significant challenge.Herein,we report on a novel and facile strategy to construct the ordered and aligned MoS_(2)nanosheet-encapsulated metal–organic frameworks(MOFs)derived hollow CoS polyhedron,in-situ grown on a nickel foam(NF).The starfish-like MoS_(2)/CoS/NF heterojunctions were formed due to the ordered growth of the material caused by NF substrate.The optimized 2-MoS_(2)/CoS/NF heterojunction exhibits robust bifunctional electrocatalytic activity with a low overpotential of 67 and 207 m V toward the HER and OER at 10 mA cm^(-2),and the long-term stability,which exceeds most of the reported bifunctional electrocatalysts.Such high electrocatalytic performance arises due to the synergistic effect between the MoS_(2)and CoS phases across the interface,the abundant active sites,as well as the hierarchical pore framework,which collectively enhance the mass and electron transfer during the reactions.The work provides a promising approach to fabricating bifunctional catalysts with custom-designed heterojunctions and remarkable performance for applications in electrochemical energy devices and related areas.

3D-ordered macroporous N-doped carbon encapsulating Fe-N alloy derived from a single-source metal-organic framework for superior oxygen reduction reaction

Fe-N compounds with excellent electrocatalytic oxygen reduction activity are considered to be one of the most promising non-precious metal materials for fuel cells.Fe-N compounds with excellent electrocatalytic oxygen reduction activity are considered to be one of the most promising non-precious metal materials for fuel cells,which focuses on the Fe-N4 single-atom catalysts and the iron nitride materials(such as Fe2N and Fe3N).A hybridized catalyst having a hierarchical porous structure with regular macropores could enable the desired mass transfer efficiency in the catalytic process.In this study,we have constructed a new type of hybrid catalyst having iron and iron-nitrogen alloy nanoparticles(Fe-N austenite,termed as Fe-NA)embedded in the three-dimensional ordered macroporous N-doped carbon(3DOM Fe/Fe-NA@NC)by direct pyrolysis of single-source dicyandiamide-based iron metal-organic frameworks.The as-synthesized composites preserve the hierarchical porous carbon framework with ordered macropores and high specific surface area,incorporating the uniformly dispersed iron/iron-nitrogen austenite nanoparticles.Thereby,the striking architectural configuration embedded with highly active catalytic species delivers a superior oxygen reduction activity with a half-wave potential of 0.88 V and a subsequent superior Zn-air battery performance with high open-circuit voltage and continuous stability as compared to those using a commercial 20%Pt/C catalyst.

Uniform zinc deposition on O,N-dual functionalized carbon cloth current collector

The society’s urgent demand for environmentally friendly, safe and low-cost energy storage devices has promoted the research of aqueous zinc-ion batteries. However, the uneven deposition of Zn ions on anodes will lead to the growth of the dendrite and reduce the Coulombic efficiency as well as the lifespan of the devices. Herein, we construct an O,N-dual functionalized carbon cloth current collector via a simple hydrothermal strategy, in which the oxygen-containing functional groups and the N heteroatoms can regulate the transmission and deposition of Zn ions, respectively. The proposed synergistic strategy ensures the uniform distribution of Zn ions on the surface of the Zn anode and inhibits the formation of dendrites. The symmetric cell based on the O,N-dual doped carbon cloth presents superior cycling stability(318 h) with a low voltage hysteresis(11.2 mV) at an areal capacity of 1 m Ah cm^(-2)(20% depth of diacharge). Meanwhile, the appreciably low overpotential(16 m V) and high Columbic efficiency(98.2%)also demonstrate that the O,N-dual functionalized carbon cloth can be worked as a promising host for Zn ions deposition.

Vapor-and temperature-triggered reversible optical switching for multi-response Cu_(8)cluster supercrystals

Multi-response metal cluster supercrystal materials,which can simultaneously display various such as color,photoluminescence,changes by bearing only one stimulus,have huge potential as stimuliresponsive intelligent material,but are rarely reported.Here,we report three Cu_(8)cluster supercrystals,Cu_(8)-1,Cu_(8)-2,and Cu_(8)-3,with homologous cluster molecule units[Cu_(8)(PNP)_(3)(EPPTA)_(6)](PF_(6))_(2)but distinct packing.These supercrystals display brightμs-long photoluminescence with a high quantum yield of up to 26.6%in solid-state at room temperature and aggregation-induced emission(AIE)characteristic.Superior thermal stability and blue-excitable bright yellow emission make Cu_(8)-3 serve as a yellow phosphor for white light-emitting diode.Furthermore,upon being stimulated by solvent vapor and temperature,reversible supercrystal-to-supercrystal transformations can be witnessed accompanied by remarkable color and luminescence switching.This work not only provides a kind of Cu cluster supercrystal model but also motivates the further development of metal clusters in multi-response materials.

The guest CH_(3)CN molecule triggers solid-state photochromism in a Cu_(2)I_(2)-based MOF for advanced time-dependent encryption and inkless erasable printing

It remains a big challenge to develop solid-state stimuli-responsive materials for time-dependent information encryption and inkless erasable printing with long retention times.Herein,a 2D Cu_(2)I_(2)-based MOF with photoresponsive spiropyran(SP)groups orderly installed on its skeleton is developed.The structural isomerization from SP to colored merocyanine(MC)form can be triggered by removing the CH_(3)CN guests.Besides,the degree of structural isomerization and the retention time can be adjusted by controlling the amount of CH_(3)CN guests,exhibiting dynamic photochromic behavior with multicolor states and tunable retention time.Based on these advantages,time-dependent information encryption is successfully achieved.Furthermore,the long retention time(>72 h)of the MC form under daylight conditions in the CH_(3)CN-removed Cu_(2)I_(2)-based MOF and good repeatability make it promising in various applications,such as temporary calendars,price-cards,billboards,and reusable identity cards.This work provides a novel design strategy to fabricate multi-functional MOF-based smart materials for challenging applications of time-dependent information encryption and inkless erasable printing.

Constructing energetic covalent organic frameworks with high stability and low sensitivity

Developing new functional explosives that display high stability,good energy performance,and low sensitivity are one of the key directions of energetic materials research.In this work,two-dimensional(2D)Schiff-based energetic covalent organic frameworks(COFs)are prepared based on triaminoguanidine salts with different anions as building blocks.Benefiting from the robust covalent bond in 2D extended polygons and strongπ-πinteractions in the eclipsed interlayers,the synthesized energetic COFs showed higher thermal stability and lower mechanical sensitivity than their precursor salts.More importantly,incorporating triaminoguanidine salts into COFs effectively increase the corrosion resistance to metal under high humidity conditions,which is due to the imine moieties in COFs functioning asπacceptors and offering strong bonding with metallic ions.This work provides a new pathway for the development of high-performance energetic materials.

Regulating electrochemical performance of Cu_(7)S_(4) electrodes via ligand engineering in copper cluster precursors

Cu-based chalcogenide materials exhibit significant promise for the development of Zn-metal-free anode materials for aqueous Zn-ion batteries (AZIBs). Here, we present the establishment of an efficient and universal strategy that capitalizes on the pyrolysis of copper nanoclusters to fabricate conversion-type Cu_(7)S_(4) anodes engineered for AZIBs, showcasing outstanding electrochemical performance. Furthermore, by exploiting ligand engineering, we enable the precise control of both the type of molecular fragments generated during nanocluster pyrolysis, thus enabling the manipulation of vacancy concentrations and ion/electron migration in the resultant pyrolysis products. In contrast to the direct pyrolysis of metal salts and ligands, the products derived from copper nanoclusters exhibit enhanced specific capacity, rate performance, and overall stability. This research offers valuable insights for the development of novel electrode materials through the pyrolysis of atomically precise nanoclusters.

Engineering intelligent chiral silver cluster-assembled materials for temperature-triggered dynamic circularly polarized luminescence

The development of stimuli-responsive circularly polarized luminescence(CPL)materials is quite attractive but challenging.Here,a pair of atomically precise enan-tiomers R/S-Ag20 nanoclusters has been synthesized using chiral acid ligands.And then,stimuli-responsive CPL materials were developed by assembling the chiral silver nanoclusters with an achiral bridging ligand.The atomically precise silver cluster-assembled materials produce CPL with a dissymmetry factor(|glum|)of 1×10-3,through the high-efficiency chiral induction process.More interestingly,the single CPL band at room temperature could quickly transform into highly separated dual CPL emissions at low temperature.This study provides a new strategy for the rational functionalization of chiral silver clusters in preparing cluster-based CPL emitters and enriches the types of stimuli-responsive CPL materials.

Integrating Homogeneous and Heterogeneous Catalysis in a Copper Nanocluster with Lewis Acid–Base Sites for Chemical Conversion of CO_(2) and Propargylamine

It remains a significant challenge to develop a catalyst that merges the advantages of homogeneous and heterogeneous catalysis with high reactivity and great recyclability.Herein,an atomically precise Cu_(6)-NH_(2) nanocluster with distorted octahedral Cu_(6) core and NH_(2)-functionalized ligands has been developed as the first homo/heterogeneous catalyst to catalyze the cyclization reaction of propargylic amines with carbon dioxide(CO_(2))under mild conditions.As a homogeneous catalyst,Cu_(6)-NH_(2) shows excellent catalytic activity with high turnover frequency due to highly accessible active sites.The definite coordination geometry and homogeneity nature of active centers make it convenient to investigate the structure–activity relationship at the atomic level through experiments and theory calculations.In addition,the nanocluster exhibits excellent stability,great recrystallizability,and reusability in five catalytic cycles,in which its catalytic performance has no obvious decrease.Moreover,Cu_(6)-NH_(2) incorporates Lewis acid and base sites in metal and ligand,respectively,which can promote catalytic efficiency in a synergistic effect in the absence of any cocatalysts.Importantly,Cu_(6)-NH_(2) can realize direct conversion of CO_(2) in simulated flue gas into oxazolidinones with high efficiency.The metal-ligand cooperative effect and integrated advantages of homogeneous and heterogeneous catalysis would provide new perspectives to achieve advanced metal nanocluster catalysts for CO_(2) conversion.

Multi-stimuli-responsive aggregation-induced emission copper iodide cluster

Stimuli-responsive luminescent materials have attracted significant attention in the development of smart photoactive materials for both fundamental research and technological applications.In this work,a new copper iodide cluster(1)with aggregationinduced emission(AIE)characteristic,was obtained combining Cu_(4)I_(4) core with rhodamine B derivative ligand.1 has reversible and distinct multi-stimuli-responsive luminescence for external temperature,volatile organic compound,and mechanical force.Significantly,1 exhibited unusual large blue shift(84 nm)after being ground,which originated from the change of intermolecular interactions.Moreover,1 exhibits high oxygen quenching efficiency for 82.2% at 1 bar.Mechanistic studies showed that the multi-stimuli-responsive luminescence properties of 1 can be attributed to the regulation of cluster-centered luminescence process,metal-to-ligand charge transfer process,halide-to-metal charge transfer luminescence process and aggregationinduced barrier to oxygen process.This work not only reports an AIE copper iodide cluster,but also provides a new strategy to develop multi-stimuli-responsive luminescence materials.

Regulation of Coordinating Anions around Single Co(Ⅱ)Sites in a Covalent Organic Framework for Boosting CO_(2)Photoreduction

While photocatalytic CO_(2)reduction has been intensively investigated,reports on the influence of anions coordinated to catalytic metal sites on CO_(2)photoreduction remain limited.Herein,different coordinated anions(F^(−),Cl^(−),OAc^(−),and NO_(3)^(−))around single Co sites installed on bipyridine-based three-component covalent organic frameworks(COFs)were synthesized,affording TBD-COF-Co-X(X=F,Cl,OAc,and NO3),for photocatalytic CO_(2)reduction.Notably,the presence of these coordinated anions on the Co sites significantly influences the photocatalytic performance,where TBD-COF-Co-F exhibits superior activity to its counterparts.Combined experimental and theoretical results indicate that the enhanced activity in TBD-COF-Co-F is attributed to its efficient charge transfer,high CO_(2)adsorption capacity,and low energy barrier for CO_(2)activation.This study provides a new strategy for boosting COF photocatalysis through coordinated anion regulation around catalytic metal sites.

Frontiers in circularly polarized luminescence:molecular design,self-assembly,nanomaterials,and applications

The research in circularly polarized luminescence has attracted wide interest in recent years.Efforts on one side are directed toward the development of chiral materials with both high luminescence efficiency and dissymmetry factors,and on the other side,are focused on the exploitations of these materials in optoelectronic applications.This review summarizes the recent frontiers(mostly within five years)in the research in circularly polarized luminescence,including the development of chiral emissive materials based on organic small molecules,compounds with aggregation-induced emissions,supramolecular assemblies,liquid crystals and liquids,polymers,metal-ligand coordination complexes and assemblies,metal clusters,inorganic nanomaterials,and photon upconversion systems.In addition,recent applications of related materials in organic light-emitting devices,circularly polarized light detectors,and organic lasers and displays are also discussed.

An efficient and versatile biopolishing strategy to construct high performance zinc anode

Conventional strategies for highly reversible Zn anodes usually involve complex and time-consuming production processes of current collectors,expensive and toxic electrolyte additives,or the introduction of inactive materials in protective layer.Here,we develop a fast,facile,and environmentally friendly biopolishing method to prepare dendrite-free Zn anodes,which merely involves the simple immersion of Zn foil in a biocompatible cysteine aqueous solution.The ravine structure formed by sulfhydryl etching for 30 min not only increases the electroactive area of Zn anode but also regulates the distribution of electric field and Zn ions,ensuring the homogeneous deposition and stripping of Zn ions.The biopolished Zn anode can be operated steadily for 2,000 h with a low voltage hysteresis at a current density of 1 mA·cm^(−2).In addition,Zn anodes with a cycle life of 500 h can be built by soaking for only 5 min,proving the high efficiency of the proposed method.This strategy is generalized to substances with sulfhydryl groups for polishing Zn electrodes with improved performance.The cysteine-polished Zn//activated carbon supercapacitor can stably run for 20,000 cycles without obvious capacity attenuation.The proposed strategy shows potential for producing advanced Zn anodes.

Integration of enzyme immobilization and biomimetic catalysis in hierarchically porous metal-organic frameworks for multi-enzymatic cascade reactions

Multiple enzymes-induced biological cascade catalysis is indispensable in biotechnology and industrial processes. Nevertheless,the drawbacks of most natural enzymes, including poor stability and recyclability and sensitivity to the environment, have hindered their broader application. Here, we report a facile strategy to prepare a biomimetic cascade reaction system by combining the advantages of enzyme immobilization and biomimetic catalysis in a one-pot reaction system based on the hierarchically porous metal-organic frameworks(HP-MOFs). The hierarchically porous zirconium-porphyrin-based MOF(HPPCN-222(Fe)) synthesized by modulator-induced strategy possessed tunable hierarchical porous and peroxidase-like activity,permitting them to act as not only an efficient immobilization matrix for glucose oxidase(GOx) but also peroxidase mimics to catalyze the cascade for glucose detection. A stable, anti-interference and reusable colorimetric biosensor for glucose detection was successfully established through GOx@HP-PCN-222(Fe) on the basis of the artificial tandem catalysis. Moreover, the GOx@HP-PCN-222(Fe)-fabricated electrode was available for glucose detection by electrochemical method. This work provides a potentially universal method to design functional multi-enzymatic cascade reaction systems by integrating the merits of enzyme encapsulation and biomimetic catalysis in HP-MOFs.

Sub-2 nm IrO_(2)/Ir nanoclusters with compressive strain and metal vacancies boost water oxidation in acid

IrO_(2)exhibits good stability but limited electrocatalytic activity for oxygen evolution reaction in acid.Defect engineering is an effective strategy to improve the intrinsic ability of electrocatalysts by tailoring their electronic structure.Herein,we have successfully synthesized IrO_(2)/Ir heterophase with compressive strain and metal vacancies via a simple substitution-etching method.In virtue of the solubility of Cr in strong alkali,metal vacancies could be formed at surface after etching Cr-doped IrO_(2)/Ir in alkali,which leaded to modulated electronic structure.Meanwhile,the substitution of Cr with smaller atom radius would induce the formation of compressive strain and the relocated atoms made the d-band center shifted.With the regulated electronic structure and tuned d-band center,the obtained electrocatalyst only needed 285 mV to reach 10 mA·cm^(−2)in 0.1 M HClO4.Reaction kinetic has been rapidly accelerated as indicated by the smaller Tafel slope and charge transfer resistance.Theoretical calculations revealed that the d-band center and charge density distribution have been regulated with the introduction of defects in IrO_(2)/Ir,which significantly decreased the free energy barrier of rate determining step.This work provides a valuable reference to design effective and defects-rich electrocatalysts.

Rational designed isostructural MOF for the charge-discharge behavior study of super capacitors

In recent years,the rapid charge-discharge property of super capacitors based on metal-organic frameworks(MOFs)has seen excellent applications in energy storage equipment.However,the purposeful design of high-performance electrodes for MOFderived super capacitors is still an urgent problem that needs to be solved.Herein,we rationally design and prepare three MOFs with the same crystal configuration and controllable functional groups.Through the combination of rigorous experiment and calculation,we have verified the effects of the specific surface area of the electrode material as well as the binding energy between the electrode material and the electrolyte ions on the performance of the super capacitor.This work not only extends the application of MOFs,but also provides a model-material platform for the study of charge–discharge behavior of MOF-based super capacitors,creating a way of thinking for the selection and design of MOF materials for energy storage applications.

Reversible Wide-Range Tuneable Luminescence of a Dual-Stimuli- Responsive Silver Cluster-Assembled Material

Background and Originality Content In recent years,the construction of atomically precise noble metal nanoclusters has been extensively studied[1] owing to their favorable photophysical properties and promising applications in photoluminescent materials,optical sensors,catalysis,and biological labelling.[2,3] As a distinct family of noble metal clusters,silver chalcogenolate clusters(SCCs)[4]are a new category of materials with many unusual properties.

Alkynyl-anchored silver nanoclusters in lanthanide metal-organic framework for luminescent thermometer and CO_(2) cycloaddition

In this study,an alkynyl-modified aromatic dicarboxylic acid bifunctional ligand was selected to construct lanthanide compound{[Eu_(4)(ebdc)_(6)(4,4-bpy)_(0.5)(H_(2)O)_(4.5)]·(C_(2)H_(5)OH)_(1.25)(H_(2)O)}_(n)(Eu-MOF,H_(2)ebdc=5-ethynyl-isophthalic acid,4,4-bpy=4,4-bipyridine,MOF=metal-organic framework),of which the uncoordinated alkynyl group would be used to anchor silver nanoclusters(Ag NCs).The Eu-MOF exhibits double emission peaks,located at 492 and 611 nm,respectively,in which the high-energy blue emission is associated with alkynyl-modified ligand while the low-energy red emission belongs to characteristic emission of Eu3+,indicating that ligands can effectively sensitize Eu3+luminescence.The intensity ratio of the dual emission fluorescence peaks of Eu-MOF displays a good linear relationship with temperature,which realizes the detection function in the low temperature region of 75–275 K,the thermal sensitivity reaches 1.5398%·K^(−1).After anchoring the Ag NCs,the high-energy blue emission is significantly quenched,indicating that the Ag NCs are indeed confined into the framework and interact with the alkynyl group,and thus change the overall electronic distribution.This is the first case of anchoring Ag NCs by a luminescent Eu-MOF and studying nanocluster loading by using spectroscopic properties.In addition,the Ag NCs@Eu-MOF also shows a good catalytic activity for cycloaddition reaction from CO_(2)and epoxides.This study not only provides ideas for exploring the changes in optical properties of luminescent MOFs and Ag NCs caused by confinement effect,but also expands their potential applications in various fields.

Engineering intermolecular charge transfer in chiral organometallic crystals by rational doping for high-contrast CPL switches

The development of circularly polarized luminescence(CPL)switches is of great importance but challenging.Herein,a charge donor/acceptor pair comprising two chiral gold(I)-isocyanide complexes was designed to construct light-harvesting system via intermolecular charge-transfer(CT)interactions.By doping nonemissive S-Au I into blue-emitting S-AuCN,(S-Au CN)_(1-x)(S-AuI)_(x)(0≤x≤3.4%)with tunable emission from blue to red was achieved.This large red-shifted emission was realized based on the remarkable change of the electronic properties between the S-Au CN dimer and red-emitting(S-A CN)-(S-AuI)CT pair,and the resulting energy-transfer(En T)process between them.Importantly,the En T process can be switched off/on by external stimuli of grinding and CH_(2)Cl_(2)fuming,giving rise to high-contrast(blue versus red)CPL switching properties.This study opens a novel avenue for developing CPL switches by constructing light-harvesting CT-doped systems based on chiral organometallic complexes.