Recent progress in structural modulation of metal nanomaterials for electrocatalytic CO_(2) reduction

The electrochemical CO_(2) reduction(ECR)into value-added products presents an appealing approach to mitigate CO_(2) emission caused by excess consumption of fossil fuels.To obtain high catalytic activity and selectivity toward target product in ECR,designing and developing a stable and efficient electrocatalyst is of significant importance.To date,metal nanomaterials have been widely applied as electrocatalysts for ECR due to their unique physicochemical properties.The structural modulation of metal nanomaterials is an attractive strategy to improve the catalytic performance.In this review,the recent progress of structural modulation,including size,facet,grain boundary,composition,interface,ligand modification,and crystal phase,is systematically summarized from both theoretical and experimental aspects.Finally,the opportunities and perspectives of structural modulation of metal nanomaterials for ECR are proposed.

Chiral metal nanostructures:synthesis,properties and applications

Chirality,the property that an object cannot coincide with its mirror image arising from lack of mirror symmetry,is ubiquitous in nature at various length scales.The physical and chemical properties are strongly related to the nature of chiral complexes,playing a significant role in various fields such as photonics,biochemistry,medicine and catalysis.In particular,the recent flexible design of chiral metal nanostructures offers one platform for deeply understanding the origin of chirality and one roadmap for the precise construction of chiral nanomaterials directed by the applications.Herein,we summarize the different geometries and classical synthetic approaches to chiral noble metal nanomaterials.Moreover,chiroptical properties and potential applications of chiral metal nanostructures are discussed as well.Finally,the opportunities and challenges toward the synthesis and application of chiral metal nanostructures are proposed.

Tuning the growth of metal-organic framework nanocrystals by using polyoxometalates as coordination modulators

Host-guest supramolecular interactions, which exist widely between diverse metal cations and polyoxometalate(POM) anions, have always been utilized to construct metal-organic frameworks(MOF) /POMs bulk composites. Actually, the interactions can also be found application in realizing shape-controlled synthesis of MOF nanocrystals(NCs). In this context, simply by introducing Keggin-type POMs into MOF precursors, various uniform [Cu3(BTC)2]n(BTC = benzene-1,3,5-tricarboxylate) NCs, including(truncated) octahedrons, hollow hierarchical spheres and octahedrons, are fabricated. Besides, such reaction system can be applied to construct noble metal@MOF nanocomposite, which significantly enhances the catalytic performance of the noble metal.

Understanding the dehydrogenation mechanism over iron nanoparticles catalysts based on density functional theory

The conversion of chemical feedstock materials into high value-added products accompanied with dehydrogenation is of great value in the chemical industry.However,the catalytic dehydrogenation reaction is inhibited by a limited number of expensive noble metal catalysts and lacks understanding of dehydrogenation mechanism.Here,we report the use of heterogeneous non-noble metal iron nanoparticles(NPs) incorporated mesoporous nitrogen-doped carbon to investigate the dehydrogenation mechanism based on experiment observation and density functional theory(DFT) method.Fe NPs catalyst displays excellent performance in the dehydrogenation of 1,2,3,4-tetrahydroquinoline(THQ)with 100% selectivity and 100% conversion for 10-12 h at room temperature.The calculated adsorption energy implies that THQ prefers to adsorb on Fe NPs as compared with absence of Fe NPs.What is more,the energy barrier of transition state is relatively low,illustrating the dehydrogenation is feasible.This work provides an atomic scale mechanism guidance for the catalytic dehydrogenation reaction and points out the direction for the design of new catalysts.

Insight into crystal growth and upconversion luminescence property of tetragonal Ba_(3)Sc_(2)F_(12) nanocrystals

Sc-based nanomaterials have attracted considerable attention due to their unique optical properties different from those of Ln/Y-based nanomaterials.However,studies on Sc-based nanomaterials are far from comprehensive.Particularly,nanoscale alkaline(Ca,Sr and Ba)scandium fluorides were almost ignored for their stringent synthetic conditions.Herein,we synthesize high-quality tetragonal phase Ba_(3)Sc_(2)F_(12) nanocrystals with uniform morphology and good dispersibility by carefully tailoring the reaction conditions,such as the molar ratio of reactants,temperature and reaction time.Then,the upconversion(UC)luminescence property of Ba_(3)Sc_(2)F_(12):Yb/Er(Ho)samples is investigated in detail.The doping concentrations of sensitizer(Yb^(3+))and activator(Er^(3+)and Ho^(3+))are optimized for the strongest UC luminescence,of which the corresponding energy transfer processes are also discussed.Moreover,tetragonal Ba_(3)Sc_(2)F_(12) nanocrystals can gradually transform into hexagonal Ba_(4)Yb_(3)F_(17) nanocrystals with the increase in Yb^(3+)doping content.This work provides a novel type of Sc-based nanomaterials with strong red UC emissions which are promising in high-resolution 3-dimensional color displays,laser,bioimaging and biolabels.