An overview on importance, synthetic strategies and studies of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(HNIW)

2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(HNIW), commonly called as CL-20, is a high energy and high density material of keen interest to both commercial and scientific worlds due to its greater insensitivity(reduced sensitivity) along with a positive high heat of formation, which is due to the azanitro groups attached to the skeleton of HNIW and its highly strained cage structure. It plays a remarkable role in modification and replacement of most of the propellant(gun and rocket) preparations. In this report we present the comparative strategies involved in the syntheses of HNIW with respect to economical and environmental aspects. Various methods reported in the literature on the purification of the crude HNIW(α-HNIW) to obtain ε-form of HNIW(high dense/more potential) are consolidated. Understanding of the structure, morphology, energetics, thermal behavior and their modification to meet the applicability(decreased impact sensitivity) determines the industrial application of HNIW. A compilation of the available literature on the aforementioned characteristic properties for obtaining a value added ε-HNIW is discussed here. This overview also reports the literature available on newer forms of HNIW including derivatives and cocrystals,which increase the performance of HNIW.

Recent Progress on Asymmetric Carbon- and Silica-Based Nanomaterials: From Synthetic Strategies to Their Applications

Carbon-and silica-based nanomaterials possess a set of merits including large surface area,good structural stability,diversified morphology,adjustable structure,and biocompatibility.These outstanding features make them widely applied in different fields.However,limited by the surface free energy effect,the current studies mainly focus on the symmetric structures,such as nanospheres,nanoflowers,nanowires,nanosheets,and core-shell structured composites.By comparison,the asymmetric structure with ingenious adjustability not only exhibits a larger effective surface area accompanied with more active sites,but also enables each component to work independently or corporately to harness their own merits,thus showing the unusual performances in some specific applications.The current review mainly focuses on the recent progress of design principles and synthesis methods of asymmetric carbon-and silica-based nanomaterials,and their applications in energy storage,catalysis,and biomedicine.Particularly,we provide some deep insights into their unique advantages in related fields from the perspective of materials’structure-performance relationship.Furthermore,the challenges and development prospects on the synthesis and applications of asymmetric carbon-and silica-based nanomaterials are also presented and highlighted.

Revisiting traditional and modern trends in versatile 2D nanomaterials: Synthetic strategies, structural stability, and gas-sensing fundamentals

Two-dimensional nanomaterials(2DNMs)have attracted significant research interest due to their outstanding structural properties,which include unique electrical nanostructures,large surface areas,and high surface reactivity.These adaptable materials have outstanding physicochemical characteristics,making them useful in a variety of applications such as gas-sensing,electronics,energy storage,and catalysis.Extensive research has been conducted in the pursuit of high performance room-temperature(RT)gas sensors with good selectivity,high sensitivity,long-term stability,and rapid response/recovery kinetics.Metal oxides,transition metal chalcogenides,MXenes,graphene,phosphorene,and boron nitride have all been discovered as 2DNMs with strong potential for gas sensors.This review presents an in-depth analysis of current advances in 2DNM research.It includes synthetic techniques,structural stabilities,gas-sensing mechanisms,critical performance parameters,and factors influencing gas-sensing capabilities of 2DNMs.Furthermore,the present study emphasizes structural engineering and optimization methodologies that improve gas-sensing performance.It also highlights current challenges and outlines future research directions in the domain of tailoring 2DNMs for advanced RT gas sensors.This systematically designed comprehensive review article aims to provide readers with profound insights into gas detection,thereby inspiring the generation of innovative ideas to develop cutting-edge 2DNMs-based gas sensors.

Recent advances in metal-free CDs/g-C_(3)N_(4) photocatalysts:Synthetic strategies,mechanism insight,and applications

Carbon dots/graphite carbon nitride(CDs/g-C_(3)N_(4)),a novel composite photocatalyst,has shown great po-tential for applications in energy regeneration and environmental remediation owing to its following advantages:metal-free,low cost,easily tunable,and excellent photocatalytic performance.Hence,we reviewed the development of synthetic strategies,photocatalytic enhancement mechanisms,and pho-tocatalytic applications of CDs/g-C_(3)N_(4) in this study.First,the three composite strategies of CDs and g-C_(3)N_(4)-self-assembly,solvothermal,and calcination polymerization are outlined,and their advantages and disadvantages are described in detail.Moreover,the photocatalytic enhancement mechanism of the com-posite strategies was elucidated according to the variation trends of CDs/g-C_(3)N_(4) band structure,electronic properties,light absorption range,and interfacial charge transfer.Then,the applications of CDs/g-C_(3)N_(4) in hydrogen evolution,pollutant degradation,CO_(2) reduction,and bacterial disinfection in recent years are reviewed systematically.Finally,the current obstacles and future research directions of CDs/g-C_(3)N_(4) are discussed from the perspective of preparation technology and practical applications,respectively.

Amorphous molybdenum sulfide and its Mo-S motifs:Structural characteristics,synthetic strategies,and comprehensive applications

Amorphous materials are one kind of nonequilibrium materials and have become one of the most active research fields.Compared with crystalline solids,the theory of amorphous materials is still in infancy because their characteristic of atomic arrangement is more like liquid and has no long-range periodicity.Recently,as the representative of amorphous materials,amorphous molybdenum sulfide(a-MoS_(x))with unique physical and chemical properties has been studied extensively.However,considerable debate surrounds the structure–property relationships of a-MoS_(x)owing to its diverse Mo-S motifs.Herein,we summarize recent discoveries and research results regarding a-MoS_(x),whose structural characteristics,synthetic strategies,formation criteria,and comprehensive applications are discussed in detail.Finally,this review is ended with our personal insights and critical outlooks over the development of a-MoS_(x).

Synthetic Strategies,Diverse Structures and Properties of Copper Halide Cluster-based Materials

Copper halide clusters have become one of the most prosperous cluster-based materials.They are not only widely used in the fields of photophysics and photochemistry,but also adsorption,catalysis,biology,etc.Herein,the recent progress in copper halide based chemistry is reviewed from three aspects.In the first place,we summarize the new synthesis strategies promoting the crystallization of copper halide cluster-based materials.Then,the structural diversity of the compounds is introduced according to the dimension of copper halogen clusters.Finally,we discuss the functionality of copper halide cluster-based materials including optical,catalytic and adsorption properties.In addition,perspectives on their potential applications are presented.

From nanoparticles to single atoms for Pt/CeO2:Synthetic strategies,characterizations and applications

Pt/CeO2 catalysts with unitary Pt species,nanoparticles,clusters or single atoms,often exhibit excellent activity and unique selectivity in many catalytic reactions benefiting from their small size,abundant unsaturated active sites,and unique electro nic structure.In recent years,a tre mendous number of related articles have provided great inspiration to future research and development of Pt/CeO2 catalysts.In this review,the state-of-the-art evolution of Pt nanoparticles to Pt single atoms on CeO2 is reviewed with the emphasis on synthetic strategies,advanced characterization techniques(allowing one to clarify the single atoms from clusters),the catalytic applications and mechanisms from the viewpoint of theoretical calculation.Finally,the critical outlooks and the challenges faced in developing the single-atom Pt/CeO2 catalysts are highlighted.

Synthetic strategies for chiral metal-organic frameworks

In recent years, metal-organic frameworks（MOFs） have attracted great attention owing to their potential applications such as in gas storage and separation, catalysis, luminescence and nonlinear optics. Chirality is widespread in the nature and chiral MOFs can be used in chiral recognition, chiral separation, chiral catalysis and so on. In this review, the synthetic strategies of chiral MOFs are briefly summarized. The advantages and disadvantages of those strategies and their applications are discussed.

Generalized CAPP and synthetic evaluation strategy for production line of accuracy welding

This paper presents generalized CAPP （G-CAPP） method which deals with macro process planning for multiobjective in the planning stage of production line of accuracy welding （PLAW） based on the features of accuracy welding production （ AWP ）. G-CAPP offers foundations for prototype design and general equipment sorting, production capacity predication and production analysis by means of simulation and optimization. A synthetic hierarchy evaluation （SHE） model for G-CAPP established according to the planning objective is utilized to estimate the alternate processing plans by using membership function and analytic hierarchy process （AHP） of operational theory. The assembly welding line of hydraulic torque converter （HTC） is as an example of typical A WP to explicate G-CAPP and synthetic evaluating strategy of PLAW. The feasible and rational process configuration strategies of HTC assembly welding line are pointed oat under different planning objective.

Recent advances of transition-metal metaphosphates for efficient electrocatalytic water splitting

Sustainable production of H2 through electrochemical water splitting is of great importance in the foreseeable future.Transition-metal metaphosphates(TMMPs)have a three-dimensional(3D)open-framework structure and a high content of P(which exists as PO3-),and therefore have been recognized as highly efficient catalysts for oxygen evolution reaction(OER)and the bottleneck of electrochemical water splitting.Furthermore,TMMPs can also contribute to hydrogen evolution reaction(HER)in alkaline and neutral media by facilitating water dissociation,and thus,overall water splitting can be achieved using this kind of material.In this timely review,we summarize the recent advances in the synthesis of TMMPs and their applications in OER and HER.We present a brief introduction of the structure and synthetic strategies of TMMPs in the first two parts.Then,we review the latest progress made in research on TMMPs as OER,HER,and overall water-splitting electrocatalysts.In this part,the intrinsic activity of TMMPs as well as the current strategy for improving the catalytic activity will be discussed systematically.Finally,we present the future opportunities and the remaining challenges for the application of TMMPs in the electrocatalysis field.

Advances on Axial Coordination Design of Single‑Atom Catalysts for Energy Electrocatalysis:A Review

Single-atom catalysts(SACs)have garnered increasingly growing attention in renewable energy scenarios,especially in electrocatalysis due to their unique high efficiency of atom utilization and flexible electronic structure adjustability.The intensive efforts towards the rational design and synthesis of SACs with versatile local configurations have significantly accelerated the development of efficient and sustainable electrocatalysts for a wide range of electrochemical applications.As an emergent coordination avenue,intentionally breaking the planar symmetry of SACs by adding ligands in the axial direction of metal single atoms offers a novel approach for the tuning of both geometric and electronic structures,thereby enhancing electrocatalytic performance at active sites.In this review,we briefly outline the burgeoning research topic of axially coordinated SACs and provide a comprehensive summary of the recent advances in their synthetic strategies and electrocatalytic applications.Besides,the challenges and outlooks in this research field have also been emphasized.The present review provides an in-depth and comprehensive understanding of the axial coordination design of SACs,which could bring new perspectives and solutions for fine regulation of the electronic structures of SACs catering to high-performing energy electrocatalysis.

Design, Synthesis, Chemistry and Biological Evaluation of Some Polyfunctional Heterocyclic Nitrogen Systems—Overview

The synthesis, preparation, chemical reactivities and biological activity of simple heterocyclic and heteropolycyclic nitrogen systems as small units as functional pyrazoles, pyridine and pyrimidine, and the related fused systems are reviewed. Among the various possible routes to the formation, isomeric structures have been cited because of patented reaching advanced phases of clinical trials, from 2000 to 2020.

Atomic level engineering of noble metal nanocrystals for energy conversion catalysis

It is commonly known that the performance of electrocatalysts is largely influenced by the size,morphology,composition,and crystalline phase of noble metal nanocrystals.However,the limited reserves and high cost of noble metals largely restrict their industrial applications.Along with the development of characterization techniques,theoretical calculations,and advanced material synthesis methods,modulating the electrocatalytic properties of noble metal nanocrystals at the atomic scale(e.g.,monolayer/sub-monolayer,single-atom alloy,ultrafine structure)has been flooding out.Engineering noble metal nanocrystals at the atomic level could not only immensely improve the noble metal atom utilization efficiency and lower the cost,but also boost the catalytic performance.In this review,we summarize the recent advanced progresses of regulating the noble metal nanocrystals at the atomic scale towards energy conversion application.Then,the challenges and perspectives of designing noble metal nanocrystals at the atomic scale in the future are discussed and considered.It is expected that this review will inspire scientists to further study precious metal-based materials for energy-oriented catalysis.

Engineering Dual Oxygen Simultaneously Modified Boron Nitride for Boosting Adsorptive Desulfurization of Fuel

Oxygen atoms usually co-exist in the lattice of hexagonal boron nitride(h-BN). The understanding of interactions between the oxygen atoms and the adsorbate, however, is still ambiguous on improving adsorptive desulfurization performance. Herein, simultaneously oxygen atom-scale interior substitution and edge hydroxylation in BN structure were constructed via a polymer-based synthetic strategy.Experimental results indicated that the dual oxygen modified BN(BN–2O) exhibited an impressively increased adsorptive capacity about 12% higher than that of the edge hydroxylated BN(BN–OH) fabricated via a traditional method. The dibenzothiophene(DBT) was investigated to undergo multimolecular layer type coverage on the BN–2O uneven surface via π–π interaction, which was enhanced by the increased oxygen doping at the edges of BN–2O. The density functional theory calculations also unveiled that the oxygen atoms confined in BN interior structure could polarize the adsorbate, thereby resulting in a dipole interaction between the adsorbate and BN–2O. This effect endowed BN–2O with the ability to selectively adsorb DBT from the aromatic-rich fuel, thereafter leading to an impressive prospect for the adsorptive desulfurization performance of the fuel. The adsorptive result was in good accordance with Freundlich and pseudo-second-order adsorption kinetics model results. Therefore, the designing of a polymer-based strategy could be also extended to other heteroatom doping systems to enhance adsorptive performance.

Recent advances in the synthesis and application of N-heterocyclic carbene-based molecular cages

N-Heterocyclic carbene(NHC)-based cages have emerged as a prominent and dynamic research area within the research field of chemistry. Leveraging the distinctive electronic and steric properties of NHC ligands, the design, synthesis, and application of these corresponding cages have garnered substantial scholarly interest. In recent years, we have witnessed the successful fabrication of diverse NHC-based cages through a range of synthetic methodologies, which hold significant potential for applications in molecular recognition and catalysis. In this review, we delve into the foundational synthetic strategies that underlie the creation of NHC-based cages, employing approaches encompassing metal–NHC chelation, coordination assembly,and covalent bonding. Additionally, we compile the diverse applications of these cages within catalytic processes and molecular recognition. Lastly, we shed light on the current limitations of synthesis and outline future trends in the development of NHCbased cages.

Strategies for the construction of supramolecular assemblies from poly-NHC ligand precursors

The field of supramolecular assemblies has developed rapidly in the last few decades,thanks in a large part to their diverse applications.These assemblies have been mostly based on Werner-type coordination motifs in which metal centres are coordinated by nitrogen or oxygen donors.Recently,N-heterocyclic carbene(NHC)ligands have been employed as carbon donors not only because of their appealing structures but also due to the extensive applications in catalysis,biomedicine and material science of the resulting assemblies.During the last decade,NHC-based supramolecular assemblies have witnessed rapid growth and extensive application in molecular recognition,luminescent materials and catalysis.For different topological systems,a diverse selection of poly-NHC precursors and synthetic strategies is crucial to precisely control the synthesis of supramolecular architectures.Several synthetic strategies have been developed to synthesise two-dimensional(2D)molecular metallacycles and three-dimensional(3D)metallacages from a wide range of poly-NHC precursors,including a straightforward one-pot strategy,supramolecular transmetalation,stepwise synthesis,an improved one-pot strategy involving self-sorting behaviour of 3D metallacages and a subtle variation strategy of poly-NHC ligand precursors.This review offers a summary of the synthetic strategies applied for the construction of different poly-NHC-based supramolecular assemblies,particularly emphasizes recent progress in the synthesis of large and complex supramolecular assemblies from poly-NHC precursors,and further attention is given to their application in postsynthetic modifications(PSMs),host-guest chemistry,luminescent properties and biomedical applications.

Unlocking single-atom catalysts via amorphous substrates

Single-atom catalysts(SACs)reveal great potential for application in catalysis due to their fully exposed active sites.In general,single atoms(SAs)and the coordination substrates need to have strong interactions or charge transfer to ensure the atomic dispersion,which requires the selection of a suitable substrate to stabilize the target atoms.Recent studies have demonstrated that amorphous materials with abundant defects and coordinatively unsaturated sites can be used as substrates for more efficient capturing SAs,further enhancing the catalytic performance.In this review,we discuss recent research progress of SAs loaded on amorphous substrates for enhanced catalytic activity.Firstly,we summarize the commonly used amorphous substrates for stabilizing SAs.Subsequently,we present several advanced applications of amorphous SACs in the field of catalysis,including electrocatalysis and photocatalysis.And then,we also clarify the synergistic mechanism between SAs and amorphous substrate on catalytic process.Finally,we summarize the challenges with our personal views and provide a critical outlook on how amorphous SACs continue to evolve.

Advance in 3D self-supported amorphous nanomaterials for energy storage and conversion

The advancement of next-generation energy technologies calls for rationally designed and fabricated electrode materials that have desirable structures and satisfactory performance.Three-dimensional(3D)self-supported amorphous nanomaterials have attracted great enthusiasm as the cornerstone for building high-performance nanodevices.In particular,tremendous efforts have been devoted to the design,fabrication,and evaluation of self-supported amorphous nanomaterials as electrodes for energy storage and conversion devices in the past decade.However,the electrochemical performance of devices assembled with 3D self-supported amorphous nanomaterials still remains to be dramatically promoted to satisfy the demands for more practical applications.In this review,we aim to outline the achievements made in recent years in the development of 3D self-supported amorphous nanomaterials for a broad range of energy storage and conversion processes.We firstly summarize different synthetic strategies employed to synthesize 3D nanomaterials and to tailor their composition,morphology,and structure.Then,the performance of these 3D self-supported amorphous nanomaterials in their corresponding energy-related reactions is highlighted.Finally,we draw out our comprehensive understanding towards both challenges and prospects of this promising field,where valuable guidance and inspiration will surely facilitate further development of 3D self-supported amorphous nanomaterials,thus enabling more highly efficient energy storage and conversion devices that play a key role in embracing a sustainable energy future.

Construction of amorphous/crystalline heterointerfaces for enhanced electrochemical processes

Amorphous nanomaterials have emerged as potential candidates for energy storage and conversion owing to their amazing physicochemical properties.Recent studies have proved that the manipulation of amorphous nanomaterials can further enhance electrochemical performance.To date,various feasible strategies have been proposed,of which amorphous/crystalline(a-c)heterointerface engineering is deemed an effective approach to break through the inherent activity limitations of electrode materials.The following review discusses recent research progress on a-c heterointerfaces for enhanced electrochemical processes.The general strategies for synthesizing ac heterojunctions are first summarized.Subsequently,we highlight various advanced applications of a-c heterointerfaces in the field of electrochemistry,including for supercapacitors,batteries,and electrocatalysts.We also elucidate the synergistic mechanism of the crystalline phase and amorphous phase for electrochemical processes.Lastly,we summarize the challenges,present our personal opinions,and offer a critical perspective on the further development of a-c nanomaterials.