Nanovilli electrode boosts hydrogen evolution:A surface with superaerophobicity and superhydrophilicity

Although tremendous efforts have been paid on electrocatalysts toward efficient electrochemical hydrogen generation,breakthrough is still highly needed in the design and synthesis of wonderful non-precious-metal electrocatalyst.Herein,a nanovilli Ni2P electrode,which with superaerophobic and superhydropholic can significantly facilitate the mass and electron transfer was constructed via a facial morphology control strategy.Meanwhile,the substitution of sluggish oxygen evolution with urea oxidation,lowering the two-electrode cell voltage to only 1.48 volts to achieve a current density of 10 mA·cm^-2.Thus,the as-constructed electrode achieves the operation of hydrogen generation by an AA battery.This work sheds new light on the exploration of other high-efficient electrocatalysts for hydrogen generation by using intermittent clean energy.     

Two-dimensional d-πconjugated metal-organic framework based on hexahydroxytrinaphthylene

The development of new two-dimensional(2D)d-πconjugated metal-organic frameworks(MOFs)holds great promise for the construction of a new generation of porous and semiconductive materials.This paper describes the synthesis,structural characterization,and electronic properties of a new d-πconjugated 2D MOF based on the use of a new ligand 2,3,8,9,14,15-hexahydroxytrinaphthylene.The reticular self-assembly of this largeπ-conjugated organic building block with Cu(II)ions in a mixed solvent system of 1,3-dimethyl-2-imidazolidinone(DMI)and H2 O with the addition of ammonia water or ethylenediamine leads to a highly crystalline MOF Cu3(HHTN)2,which possesses pore aperture of 2.5 nm.Cu3(HHTN)2 MOF shows moderate electrical conductivity of 9.01×10^-8S·cm^-1at 385 K and temperature-dependent band gap ranging from 0.75 to 1.65 eV.After chemical oxidation by l2,the conductivity of Cu3(HHTN)2 can be increased by 360 times.This access to HHTN based MOF adds an important member to previously reported MOF systems with hexagonal lattice,paving the way towards systematic studies of structure-property relationships of semiconductive MOFs.     

Highly efficient multi-metal catalysts for carbon dioxide reduction prepared from atomically sequenced metal organic frameworks

The precise control on the combination of multiple metal atoms in the structure of metal-organic frameworks(MOFs)endowed by reticular chemistry,allows the obtaining of materials with compositions that are programmed for achieving enhanced reactivity.The present work illustrates how through the transformation of MOFs with desired arrangements of metal cations,multi-metal spinel oxides with precise compositions can be obtained,and used as catalyst precursor for the reverse water-gas shift reaction.The differences in the spinel initial composition and structure,determined by neutron powder diffraction,influence the overall catalytic activity with changes in the process of in s itu formation of active,metal-oxide supported metal nanoparticles,which have been monitored and characterized with in situ X-ray diffraction and photoelectron spectroscopy studies.     

All-inorganic dual-phase halide perovskite nanorings

In the present work, we report the growth of all-inorganic perovskite nanorings with dual compositional phases of CsPbBr₃ and CsPb₂Br₅ via a facile hot injection process. The self-coiling of CsPbBr₃-CsPb₂Br₅ nanorings is driven by the axial stress generated on the outside surface of the as-synthesized nanobelts, which results from the lattice mismatch during the transformation of CsPbBr₃ to CsPb₂Br₅. The tailored growth of nanorings could be achieved by adjusting the key experimental parameters such as reaction temperature, reaction time and stirring speed during the cooling process. The photoluminescence intensity and quantum yield of nanorings are higher than those of CsPbBr₃ nanobelts, accompanied by a narrower full width at half maximum (FWHM), suggesting their high potential for constructing self-assembled optoelectronic nanodevices.

     

Controlling N-doping type in carbon to boost single-atom site Cu catalyzed transfer hydrogenation of quinoline

Single-atom site (SA) catalysts on N-doped carbon (CN) materials exhibit prominent performance for their active sites being M-N_x. Due to the commonly random doping behaviors of N species in these CN, it is a tough issue to finely regulate their doping types and clarify their effect on the catalytic property of such catalysts. Herein, we report that the N-doping type in CN can be dominated as pyrrolic-N and pyridinic-N respectively through compounding with different metal oxides. It is found that the proportion of distinct doped N species in CN depends on the acidity and basicity of compounded metal oxide host. Owing to the coordination by pyrrolic-N, the SA Cu catalyst displays an enhanced activity (two-fold) for transfer hydrogenation of quinoline to access the valuable molecule tetrahydroquinoline with a good selectivity (99%) under mild conditions. The higher electron density of SA Cu species induced by the predominate pyrrolic-N coordination benefits the hydrogen transfer process and reduces the energy barrier of the hydrogenation pathway, which accounts for the improved catalytic effeciency.

     

Direct aerobic oxidation of monoalcohol and diols to acetals using tandem Ru@MOF catalysts

The aerobic oxidation of monoalcohols and diols to acetals is an important academic and industrial challenge for the production of fine chemicals and intermediates.The existing methods usually rely on a two-step process in which alcohols are first oxidized to aldehydes over metal catalysts(Ru,Pt,Pd)and then acetalized using acids.Due to the instability of aldehydes,how to avoid over-oxidation to their respective carboxylic acids and esters is a long-standing challenge.For this reason,certain non-conjugated dialdehydes have never been successfully produced from diol oxidation.Hereby we report a Ru@metal-organic framework(MOF)tandem catalyst containing ultra-fine Ru nanoparticles(<2 nm)for direct alcohol to acetal conversion of monoalcohol and diols with noformation of carboxylic acids.Mechanistic study reveals that the presence of Lewis acid sites in the MOF work in concert with Ru active sites to promptly convert aldehydes to acetals thereby effectively suppressing the formation of over-oxidation byproducts.     

Opto-valleytronics in the 2D van der Waals heterostructure

The development of information processing devices with minimum carbon emission is crucial in this information age. One of the approaches to tackle this challenge is by using valleys (local extremum points in the momentum space) to encode the information instead of charges. The valley information in some material such as monolayer transition metal dichalcogenide (TMD) can be controlled by using circularly polarized light. This opens a new field called opto-valleytronics. In this article, we first review the valley physics in monolayer TMD and two-dimensional (2D) heterostructure composed of monolayer TMD and other materials. Such 2D heterostructure has been shown to exhibit interesting phenomena such as interlayer exciton, magnetic proximity effect, and spin-orbit proximity effect, which is beneficial for opto-valleytronics application. We then review some of the optical valley control methods that have been used in the monolayer TMD and the 2D heterostructure. Finally, a summary and outlook of the 2D heterostructure opto-valleytronics are given.

     

Living electronics

Living electronics that converges the unique functioning modality of biological and electrical circuits has the potential to transform both fundamental biophysical/biochemical inquiries and translational biomedical/engineering applications. This article will review recent progress in overcoming the intrinsic physiochemical and signaling mismatches at biological/electronic interfaces, with specific focus on strategic approaches in forging the functional synergy through: (1) biohybrid electronics, where genetically encoded bio-machineries are hybridized with electronic transducers to facilitate the translation/interpretation of biologically derived signals; and (2) biosynthetic electronics, where biogenic electron pathways are designed and programmed to bridge the gap between internal biological and external electrical circuits. These efforts are reconstructing the way that artificial electronics communicate with living systems, and opening up new possibilities for many cross-disciplinary applications in biosynthesis, sensing, energy transduction, and hybrid information processing.

     

Guest selectivity in the supramolecular host networks fabricated by van der Waals force and hydrogen bond

Here, the structural transformations of H₄ETTC induced by coronene (COR) and selective adsorption behaviors of COR in different templates were investigated by scanning tunnelling microscope (STM). It was discovered that the assembled architecture of H₄ETTC at the HOPG/ heptanoic acid interface depended on the concentration of COR, and the clusters of COR were obtained in the kagomé nanoporous network of H₄ETTC molecules at a high concentration of COR solution. In addition, COR clusters can also be formed in the hexagonal porous structure of hexaphenylbenzene (HPB) molecules modified by alkyl chains at the HOPG/heptanoic acid interface. When both H₄ETTC and HPB assembly structures, based on hydrogen bonding and van der Waals force respectively, were selected as the host templates, COR showed selectivity for HPB template to form HPB/COR hexagonal host–guest architecture. Density functional theory (DFT) calculations were also performed to disclose the mechanisms involved.

     

From a mononuclear FeL2complex to a Fe4L4molecular square:Designed assembly and spin-crossover property

By introduction of a new Fe(L¹)₂spin-crossover(SCO)unit into the polynuclear system,a nano-scale Fe4(L²)₄molecular square architecture is designed through coordination-directed self-assembly strategy.Both the mononuclear Fe(L¹)₂and tetranuclear Fe4(L²)₄complexes have bee门structurally confirmed by 1H nuclear magnetic resonance(NMR),electrospray ionization time-of-flight mass spectrometry(ESI-TOF-MS),and temperature-dependent single crystal X-ray diffraction studies.Variable-temperature magnetic susceptibility measurements reveal the presence of an abrupt SCO behavior with a thermal hysteresis width of 4K for Fe(L¹)₂.By clear contrast,Fe4(L²)₄undergoes a gradual spin transition behavior with enlarged thermal hysteresis width and higher spin transition temperature.     

Highly luminescent and stable CsPbBr3 perovskite quantum dots modified by phosphine ligands

All-inorganic cesium lead halide perovskite quantum dots (QDs) have been a promising candidate for optoelectronic devices in recent years, such as light-emitting diodes, photodetectors and solar cells, owing to their superb optoelectronic properties. Still, the stability issue of nanocrystals is a bottleneck for their practical application. Herein, we report a facile method for the synthesis of a series of phosphine ligand modified CsPbBr₃ QDs with high PL intensity. By introducing organic phosphine ligands, the tolerance of CsPbBr₃ QDs to ethanol, water and UV light was dramatically improved. Moreover, the phosphine ligand modified QD films deposited on the glass subtracts exhibit superior PL intensity and optical stability to those of pristine QD based films.

     

Rational design of hierarchically porous Fe-N-doped carbon as efficient electrocatalyst for oxygen reduction reaction and Zn-air batteries

The rational design and construction of hierarchically porous nanostructure for oxygen reduction reaction (ORR) electrocatalysts is crucial to facilitate the exposure of accessible active sites and promote the mass/electron transfer under the gas-solid-liquid triple-phase condition. Herein, an ingenious method through the pyrolysis of creative polyvinylimidazole coordination with Zn/Fe salt precursors is developed to fabricate hierarchically porous Fe-N-doped carbon framework as efficient ORR electrocatalyst. The volatilization of Zn species combined with the nanoscale Kirkendall effect of Fe dopants during the pyrolysis build the hierarchical micro-, meso-, and macroporous nanostructure with a high specific surface area (1,586 m²·g⁻¹), which provide sufficient exposed active sites and multiscale mass/charge transport channels. The optimized electrocatalyst exhibits superior ORR activity and robust stability in both alkaline and acidic electrolytes. The Zn-air battery fabricated by such attractive electrocatalyst as air cathode displays a higher peak power density than that of Pt/C-based Zn-air battery, suggesting the great potential of this electrocatalyst for Zn-air batteries.

     

(Metal yolk)/(porous ceria shell) nanostructures for high-performance plasmonic photocatalysis under visible light

We describe a route to the preparation of (metal yolk)/(porous ceria shell) nanostructures through the heterogeneous growth of ceria on porous metal nanoparticles followed by the calcination-induced shrinkage of the nanoparticles. The approach allows for the control of the ceria shell thickness, the metal yolk composition and size, which is difficult to realize through common templating approaches. The yolk/shell nanostructures with monometallic Pt and bimetallic PtAg yolks featuring plasmon-induced broadband light absorption in the visible region are rationally designed and constructed. The superior photocatalytic activities of the obtained nanostructures are demonstrated by the selective oxidation of benzyl alcohol under visible light. The excellent activities are ascribed to the synergistic effects of the metal yolk and the ceria shell on the light absorption, electron-hole separation and efficient mass transfer. Our synthesis of the (metal yolk)/(porous ceria shell) nanostructures points out a way to the creation of sophisticated heteronanostructures for high-performance photocatalysis.

     

Panorama of boron nitride nanostructures via lamp ablation

A diverse range of remarkable boron nitride (BN) nanostructures subsuming nano-horns, nano-rods, nano-platelets, and clusters of hollow nanospheres (nano-onions, arguably of greatest applied and fundamental interest) have been produced exclusively from crystalline BN precursor powder via lamp ablation. The procedure is safe, devoid of toxic reagents, simple, rapid and scalable—generating some genres of nanoparticles that had previously proved elusive. Product structure and composition were unambiguously assessed by high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy.

     

Highly active sites of low spin FeⅡN4species:The identification and the ORR performance

Over recent years,catalytic materials of Fe-N-C species have been recognized being active for oxygen reduction reaction(ORR).However,the identification of active site remains challenging as it generally involves a pyrolysis process and mixed components being obtained.Herein Fe₃C/C and Fe₂N/C samples were synthesized by temperature programmed reduction of Fe precursors in 15%CH₄/H₂and pure NH₃,respectively.By acid leaching of Fe₂N/C sample,only single sites of FeN₄species were presented,providing an ideal model for identification of catalytic functions of the single sites of FeN₄in ORR.A correlation was conducted between the concentration of Fe^ⅡN₄in low spin state by Mossbauer spectra and the kinetic current density at 0.8 V in alkaline media,and such a structure-performance correlation assures the catalytic roles of low spin Fe^ⅡN₄ species as highly active sites for the ORR.     

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.

     

Ion implantation assisted synthesis of graphene on various dielectric substrates

Direct synthesis of high-quality graphene on dielectric substrates is of great importance for the application of graphene-based electronics and optoelectronics. However, high-quality and uniform graphene film growth on dielectric substrates has proven challenging due to limited catalytic ability of dielectric substrates. Here, by employing a Cu ion implantation assisted method, high-quality and uniform graphene can be directly formed on various dielectric substrates including SiO2/Si, quartz glass, and sapphire substrates. The growth rate of graphene on the dielectric substrates was significantly improved due to the catalysis of Cu. Moreover, during the graphene growth process, the Cu atoms gradually evaporated away without involving any metal contamination. Furthermore, an interesting growth behavior of graphene on sapphire substrate was observed, and the results show the graphene domains growth tends to grow along the sapphire flat terraces. The ion implantation assisted approach could open up a new pathway for the direct synthesis of graphene and promote the potential application of graphene in electronics.     

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.

     

Novel hollow Ni0.33Co0.67Se nanoprisms for high capacity lithium storage

In this work, homogeneous Ni_0.33Co_0.67Se hollow nanoprisms were synthesized successfully in virtue of Kirkendall effect. It is the first time for bimetallic Ni-Co compounds Ni_0.33Co_0.67Se to be used in lithium-ion batteries (LIBs). Impressively, the Ni_0.33Co_0.67Se hollow nanoprisms show superior specific capacity (1,575 mAh/g at the current density of 100 mA/g) and outstanding rate performance (850 mAh/g at 2,000 mA/g) as anode material for LIBs. This work proves the potential of bimetallic chalcogenide compounds as high performance anode materials for LIBs.

     

Tumor-responsive copper-activated disulfiram for synergetic nanocatalytic tumor therapy

Exploring alternative biomedical use of traditional drugs in different disease models is highly important as it can reduce the cost of drug development and overcome several critical issues of traditional chemodrugs such as low chemotherapeutic efficiency,severe side effect,and drug resistance.Disulfiram(DSF),a clinically approved alcohol-aversion drug,was recently demonstrated tofeature tumor-growth suppression effect along with the co-administration of Cu²⁺species,but direct Cu²⁺administration mode might cause severe toxicity originating from low Cu²⁺accumulation into the tumor and nonspecific Cu²⁺distribution-induced cytotoxicity.Based on the intriguing drug-delivery performance of nanoscale metal-organic frameworks(MOFs),we herein construct HKUST nMOFs as the Cu²⁺self-supplying nanocarriers for efficient delivery of the D SF drug.The mildly acidic condition of tumor microenvironment initially triggered the release of Cu ions from HKUST nMOFs,which further reacted with the encapsulated DSF toform toxic Cu(DDTC)2(activation)for tumor chemotherapy.Especially,during the Cu(DDTC)2 complexation,Cu⁺species were formed concomitantly,triggering the intratumoral nanocatalytic therapy for the generation of reactive oxygen species to synergistically destroying the tumor cells/tissue.As a result,synergetic tumor-responsive chemotherapy and nanocatalytic therapy are enabled by DSF@HKU ST nanodrugs,as demonstrated by the dominant anticancer efficacy with satisfied biocompatibility both in vitro and in vivo.The present work offers a sophisticated strategy for tumor-responsive nontoxic-to-toxic therapeutic with high biocompatibility.