Bi_(2)S_(3)Nanorods Hosted on rGO Sheets from Pyrolysis of Molecular Precursors for Efficient Li-Ion Storage

Bismuth-based compounds with high capacity and durability are still challenging in Li-ion batteries(LIBs).In this article,Bi_(2)S_(3)nanorods hosted on reduced graphene oxide nanosheets(Bi_(2)S_(3)/rGO,BSG)are successfully prepared using molecular precursor pyrolysis strategy.1D nanorod architecture possesses preeminent kinetic characteristics,shortening the ion diffusion path and increasing the contact area between electrode and electrolyte.The large specific surface area and charge polarization of rGO at the interface promote charge transfer.The capacity of material(BSG-400)reaches 558.4 m Ah g^(-1)at 0.2 A g^(-1)after 200 cycles.The anode properties of the composite outperform those of pristine Bi_(2)S_(3).The introduction of graphene enables the interfacial interaction between rGO and Bi_(2)S_(3).The closely contact interface improves the conductivity and lithium storage performances of Bi_(2)S_(3).The regulatory effect of rGO on the electronic density of states and band gap of Bi_(2)S_(3)has been demonstrated by theoretical calculation.The synthetic approach has the advantages of universality,simple operation procedure,and strong repeatability.This research provides some ideas for the preparation of other metal sulfides/rGO nanomaterials and their application in battery research.

Development of an Analytical Method for Evaluating the Catalytic Active Sites of Titanium Silicalite Zeolite

A simple, quick, sensitive, accurate and precise method has been developed for evaluating the catalytic active sites of titanium silicalite-1 (TS-1). The catalytic active sites of titanium silicalite zeolite depend on the effectively active species (EAS) in TS-1 which react with specific substrates quickly. However, the EAS was hard to be evaluated with conventional instruments and techniques in the past. In this paper, the EAS was formed in TS-1 upon interaction with H2O2, and its presence could be confirmed by UV-vis spectroscopy which has an absorption peak at 385 nm. The absorbance at 385 nm was found to be linearly related to time, and when the absorbance and the increasing rate of absorbance (k) increased, the catalytic performance of TS-1 enhanced.

For more and purer hydrogen-the progress and challenges in water gas shift reaction

The water gas shift(WGS) reaction is a standard reaction that is widely used in industrial hydrogen production and removal of carbon monoxide. The improved catalytic performance of WGS reaction also contributes to ammonia synthesis and other reactions. Advanced catalysts have been developed for both high and low-temperature reactions and are widely used in industry. In recent years, supported metal nanoparticle catalysts have been researched due to their high metal utilization. Low-temperature catalysts have shown promising results, including high selectivity, high shift rates, and higher activity potential. Additionally, significant progress has been made in removing trace CO through the redox reaction in electrolytic cell. This paper reviews the development of WGS reaction catalysts, including the reaction mechanism, catalyst design, and innovative research methods. The catalyst plays a crucial role in the WGS reaction, and this paper provides an instant of catalyst design under different conditions. The progress of catalysts is closely related to the development of advanced characterization techniques.Furthermore, modifying the catalyst surface to enhance activity and significantly increase reaction kinetics is a current research direction. This review goals to stimulate a better understanding of catalyst design, performance optimization, and driving mechanisms, leading to further progress in this field.

A Catalytic Copper/Cobalt Oxide Interface for Efficient Hydrogen Generation

Metal nanoparticles and metal oxides promisingly provide different catalytic active sites at their interfaces.Constructing high-density interfaces is essential to maximize synergies.Herein,a Cu-Co_(3)O_(4) nanoparticles interfacial structure produced via pyrolysis and moderate oxidation from metal-organic frameworks has been designed to boost the intrinsic activity.The Cu-Co_(3)O_(4) nanoparticles composites exhibit a turnover frequency of 57.5 min−1 for ammonia borane hydrolysis,far higher than those of monometallic Cu and Co_(3)O_(4) nanoparticles,showing the synergistic effect of Cu and Co_(3)O_(4) nanoparticles at their interface.Density functional theory calculations and in situ Raman spectroscopy reveal the catalytic mechanism of dual active sites,in which Co_(3)O_(4) nanoparticles at Cu-Co_(3)O_(4) interface efficiently bind and activate water molecules and Cu nanoparticles easily activate NH3BH3 molecules.This study opens up a new pathway for achieving high-efficiency noble metal-free catalysts for hydrogen generation and other heterogeneous catalysis.

Engineering Vacancy-Atom Ensembles to Boost Catalytic Activity toward Hydrogen Evolution

The dissociation of water is the rate-determining step of several energy-relating reactions due to high energy barrier in homolysis of H-O bond.Herein,engineering vacancy-atom ensembles via injecting oxygen vacancy(V O)into single facet-exposed TiO_(2)-Pd catalyst to form V_(O)-Pd ensemble is proposed and implemented.The outstanding activity of as-prepared catalyst,1.5-PdTV_(O),toward water dissociation is established with a turnover frequency of 240 min^(−1) in ammonia borane hydrolysis at 298 K.Density functional theory simulation suggests that the V_(O)-Pd ensemble is responsible for the high intrinsic catalytic activity.Water molecules tend to be dissociated on V_(O) sites and ammonia borane molecules on Pd atoms.Those H atoms from water dissociation on V_(O) combine with H atoms from ammonia borane on Pd atoms to generate H_(2).This insights into engineering vacancy-atom ensembles catalysis provide a new avenue to design catalytic materials for important energy chemical reactions.

Polar O-Co-P Surface for Bimolecular Activation in Catalytic Hydrogen Generation

Boron hydrides release an abundant amount of hydrogen in the presence of a suitable catalyst.Accelerating bimolecular activation kinetics is the key to designing cost-effective catalysts for borohydride hydrolysis.In this study,the bimolecular activation of a polar O-Co-P site demonstrated superior hydrogen-generation kinetics(turnover frequency,TOF=37 min−1,298 K)and low activation energy(41.0 kJ mol^(−1))close to that of noble-metal-based catalysts.Through a combination of experiments and theoretical calculations,it was revealed that the activated dangling oxygen atom in the Co–O precursor effectively replaced via surface-phosphorization because of strong electronic interactions between the dangling oxygen and P atoms.This substitution modulated the local coordination environment and electronegativity around the surface Co sites and formed a new polar O-Co-P active site for optimizing the activation kinetics of ammonia borane and water.This strategy based on bimolecular activation may create new avenues in the field of catalysis.

Interface electron collaborative migration of Co–Co3O4/carbon dots:Boosting the hydrolytic dehydrogenation of ammonia borane

Ammonia borane(AB)is an excellent candidate for the chemical storage of hydrogen.However,its practical utilization for hydrogen production is hindered by the need for expensive noble-metal-based catalysts.Herein,we report Co-Co3O4 nanoparticles(NPs)facilely deposited on carbon dots(CDs)as a highly efficient,robust,and noble-metal-free catalyst for the hydrolysis of AB.The incorporation of the multiinterfaces between Co,Co3O4 NPs,and CDs endows this hybrid material with excellent catalytic activity(rB=6816 mLH2 min^-1 gCo^-1)exceeding that of previous non-noble-metal NP systems and even that of some noble-metal NP systems.A further mechanistic study suggests that these interfacial interactions can affect the electronic structures of interfacial atoms and provide abundant adsorption sites for AB and water molecules,resulting in a low energy barrier for the activation of reactive molecules and thus substantial improvement of the catalytic rate.

Co-CoO_x supported onto TiO_(2) coated with carbon as a catalyst for efficient and stable hydrogen generation from ammonia borane

Ammonia borane(AB) can be catalytically hydrolyzed to provide hydrogen at room temperature due to its high potentaial for hydrogen storage. Non-precious metal heterogeneous catalysts have broad application in the field of energy catalysis. In this article, catalysts precursor is obtained from Co-Ti-resorcinol-formaldehyde resin by sol–gel method. Co/TiO_(2)@N-C(CTC) catalyst is prepared by calcining the precursor under high temperature conditions in nitrogen atmosphere. Co-CoO_x/TiO_(2)@N-C(COTC) is generated by the controllable oxidation reaction of CTC. The catalyst can effectively promote the release of hydrogen during the hydrolytic dehydrogenation of AB. High hydrogen generation at a specific rate of 5905 m L min^(-1) g_(Co)^(-1) is achieved at room temperature. The catalyst retains its 85% initial catalytic activity even for its fifth time use in AB hydrolysis. The synergistic effect among Co, Co_(3)O_(4) and TiO_(2) promotes the rate limiting step with dissociation and activation of water molecules by reducing its activation energy. The applied method in this study promotes the development of non-precious metals in catalysis for utilization in clean energy sources.

Co_(2)N Nanoparticles Anchored on N-Doped Active Carbon as Catalyst for Oxygen Reduction Reaction in Zinc–Air Battery

The development of efficient catalytic electrode toward oxygen reduction reaction(ORR)is still a great challenge for the wide use of zinc–air batteries.Herein,Co_(2)N nanoparticles(NPs)anchored on N-doped carbon from cattail were verified with excellent catalytic performances for ORR.The onset and half-wave potentials over the optimal catalyst reach to 0.96 V and 0.84 V,respectively.Current retention rates of 96.8%after 22-h test and 98.8%after running 1600 s were obtained in 1 M methanol solution.Density functional theory simulation proposes an apparently increased electronic states of Co_(2)N in N-doped carbon layer close to the Fermi level.Higher charge density,favorable adsorption,and charge transfer of intermediates originate from the coexistence of Co_(2)N NPs and N atoms in carbon skeleton.The superior catalytic activity of composites also was confirmed in zinc–air batteries.This novel catalytic property and controllable preparation approach of Co_(2)Ncarbon composites provide a promising avenue to fabricate metal-containing catalytically active carbon from biomass.

Coupling atom ensemble and electron transfer in PdCu for superior catalytic kinetics in hydrogen generation

The design of high-performance catalysts is the key to the efficient utilization of hydrogen energy.In this work,a PdCu nanoalloy was successfully anchored on TiO_(2)encapsulated with carbon to construct a catalyst.Outstanding kinetics of the hydrolysis of ammonia borane(turnover frequency of 279 mol·min^(-1·)mol_(Pd)^(-1))ranking the third place among Pd-based catalysts was achieved in the absence of alkali.Both experimental research and theoretical calculations reveal a lower activation energy of the B-H bond on the PdCu nanoalloy catalyst than that on pristine Pd and a lower activation energy of the O-H bond than that on pristine Cu.The redistribution of d electron and the shift of the d-band center play a critical role in increasing the electron density of Pd and improving the catalytic performances of Pd_(0.1)Cu_(0.9)/TiO_(2)-porous carbon(Pd_(0.1)Cu_(0.9)/T-PC).This work provides novel insights into highly dual-active alloys and sheds light on the mechanism of dual-active sites in promoting borohydride hydrolysis.

Optical trapping and orientation of Escherichia coli cells using two tapered fiber probes

We report on the optical trapping and orientation of Escherichia coli(E.coli) cells using two tapered fiber probes.With a laser beam at 980 nm wavelength launched into probe I, an E. coli chain consisting of three cells was formed at the tip of probe I. After launching a beam at 980 nm into probe II, the E.coli at the end of the chain was trapped and oriented via the optical torques yielded by two probes. The orientation of the E. coli was controlled by adjusting the laser power of probe II. Experimental results were interpreted by theoretical analysis and numericalsimulations.

Nanostructured materials with localized surface plasmon resonance for photocatalysis

Localized surface plasmon resonance (LSPR) enhanced photocatalysis has fascinated much interest and considerable efforts have been devoted toward the development of plasmonic photocatalysts. In the past decades, noble metal nanoparticles (Au and Ag) with LSPR feature have found wide applications in solar energy conversion. Numerous metal-based photocatalysts have been proposed including metal/semiconductor heterostructures and plasmonic bimetallic or multimetallic nanostructures. However, high cost and scarce reserve of noble metals largely limit their further practical use, which drives the focus gradually shift to low-cost and abundant nonmetallic nanostructures. Recently, various heavily doped semiconductors (such as WO_(3-x), MoO_(3-x), Cu_(2-x)S, TiN) have emerged as potential alternatives to costly noble metals for efficient photocatalysis due to their strong LSPR property in visible-near infrared region. This review starts with a brief introduction to LSPR property and LSPR-enhanced photocatalysis, the following highlights recent advances of plasmonic photocatalysts from noble metal to semiconductor-based plasmonic nanostructures. Their synthesis methods and promising applicability in plasmon-driven photocatalytic reactions such as water splitting, CO_(2) reduction and pollution decomposition are also summarized in details. This review is expected to give guidelines for exploring more efficient plasmonic systems and provide a perspective on development of plasmonic photocatalysis.

Lipid droplets as endogenous intracellular microlenses

Using a single biological element as a photonic component with well-defined features has become a new intriguing paradigm in biophotonics.Here we show that endogenous lipid droplets in the mature adipose cells can behave as fully biocompatible microlenses to strengthen the ability of microscopic imaging as well as detecting intra-and extracellular signals.By the assistance of biolenses made of the lipid droplets,enhanced fluorescence imaging of cytoskeleton,lysosomes,and adenoviruses has been achieved.At the same time,we demonstrated that the required excitation power can be reduced by up to 73%.The lipidic microlenses are finely manipulated by optical tweezers in order to address targets and perform their real-time imaging inside the cells.An efficient detecting of fluorescence signal of cancer cells in extracellular fluid was accomplished due to the focusing effect of incident light by the lipid droplets.The lipid droplets acting as endogenous intracellular microlenses open the intriguing route for a multifunctional biocompatible optics tool for biosensing,endoscopic imaging,and single-cell diagnosis.

Ag nanowire/nanoparticle-decorated MoS2 monolayers for surface-enhanced Raman scattering applications

Developing well-defined nanostructures with superior surface-enhanced Raman scattering （SERS） performance is a critical and highly desirable goal for the practical applications of SERS in sensing and analysis. Here, a SERS-active substrate was fabricated by decorating a MoS2 monolayer with Ag nanowire （NW） and nanoparticle （NP） structures, using a spin-coating method. Both experimental and theoretical results indicate that strong SERS signals of rhodamine 6G （R6G） molecules can be achieved at ＂hotspots＂ formed in the Ag NW-Ag NP-MoS2 hybrid structure, with an enhancement factor of 106. The SERS enhancement is found to be strongly polarization dependent. The fabricated SERS substrate also exhibits ultrasensitive detection capabilities with a detection limit of 10-11 M, as well as reliable reproducibility and good stability.

Light-induced thermal convection for collection and removal of carbon nanotubes

Carbon nanotubes(CNTs)have exhibited immense potential for applications in biology and medicine,and once their intended purpose is fulfilled,the elimination of residual CNTs is essential to avoid negative effects.In this study,we demonstrated the effective collection and simple removal of CNTs dispersed in a suspension via thermal convection.First,a tapered fiber tip with a cone angle and end diameter of 10°and 3μm,respectively,was fabricated via a heating and pulling method.Further,a laser beam with a power and wavelength of 100 mW and 1.55^m,respectively,was launched into the tapered fiber tip,which was placed in a CNT suspension,resulting in the formation of a microbubble on the fiber tip.The temperature gradient on the microbubble and suspension surface induced thermal convection in the suspension,which resulted in the accumulation of CNTs on the fiber tip.The experimentally formed CNT cluster possessed a circular top surface with a diameter of 87 nm and an arched cross-section with a height of 19μm.Furthermore,this CNT cluster was firmly attached to the fiber tip.Therefore,the removal of CNT clusters can be realized by simply removing the fiber tip from the suspension.Moreover,we simulated the thermal convection that caused CNT aggregation.The obtained results indicate that convection near the fiber tip flows toward it,which pushes the CNTs toward the fiber tip and enables their attachment to it.Further,the flow velocity is symmetrically distributed as a Gaussian function,which results in the formation of a circular top surface and arched cross-sectional profile for the CNT cluster.Our method may be applied in biomedicine for the collection and removal of nano-drug residues.

Self-Delivery Nanoparticles of Amphiphilic Acyclic Enediynes for Efficient Tumor Cell Suppression

Summary of main observation and conclusion Four acyclic maleimide-based enediyne compounds with different hydrophilicity were synthesized through Sonogashira reaction to reveal a self-delivery antitumor drug platform. As proved by ESR analysis, the enediyne compounds undergo Bergman- like cyclizati on and generate diradical in termediates at physiological temperature, which are able to induce DNA-cleavage through the abstraction of H atoms from the sugar-phosphate backbones. When the critical aggregation concentration is reached in water, the amphiphilic enediyne compounds self-assemble into nanoparticles and possess the self-delivery ability to be facilely admitted by tumor cells, resulting in greatly improved cytotoxicity (IC50 down to 10 μmol·L^-1) and much higher tumor cell apoptosis rate (up to 86.6%) in comparison with either the hydrophilic or the lipophilic enediyne compound. The enhanced endocytosis of the amphiphilic en ediyne compo unds was further confirmed through con focal laser scan ning microscopy analysis. The unveiled relationship between the hydrophilicity of enediyne drugs and their therapeutic efficacy will provide a guideline for the design of new self-delivery drugs employed in medicinal applications.

Successive Free-Radical C(sp^(2))-C(sp^(2)) Coupling Reactions to Form Graphene

Graphene is of great interest because of its exciting properties and potential applications,but its production on a large-scale still presents considerable challenges.Herein,we report the synthesis of predominately few-layer graphene,due toπ–πstacking,and single-layer graphene from reaction between hexabromobenzene and Na metal,followed by annealing to improve crystallinity.The reaction proceeds via a free-radical C(sp^(2))–C(sp^(2))coupling mechanism,which is supported by theoretical calculations.The graphene can host unpaired spin electrons,leading to a short acquisition time for a solidstate nuclear magnetic resonance 13C spectrum from unlabeled graphene,which is ascribed to the very short spin-lattice relaxation time.High catalytic activity for transforming amine to imine with a conversion of>99%and a yield of∼97%is demonstrated,and high electronic conductivity of∼105 S·m^(−1) is found by terahertz spectroscopy.The reaction delivers a method for synthesizing graphene with a high spin concentration from perbrominated benzene molecules by using an active metallic agent,such as Na,Li,or Mg.

On-chip ultrasensitive and rapid hydrogen sensing based on plasmon-induced hot electron-molecule interaction

Hydrogen energy is a zero-carbon replacement for fossil fuels.However,hydrogen is highly flammable and explosive hence timely sensitive leak detection is crucial.Existing optical sensing techniques rely on complex instruments,while electrical sensing techniques usually operate at high temperatures and biasing condition.In this paper an on-chip plasmonic-catalytic hydrogen sensing concept with a concentration detection limit down to 1 ppm is presented that is based on a metal-insulator-semiconductor(MIS)nanojunction operating at room temperature and zero bias.The sensing signal of the device was enhanced by three orders of magnitude at a one-order of magnitude higher response speed compared to alternative non-plasmonic devices.The excellent performance is attributed to the hydrogen induced interfacial dipole charge layer and the associated plasmonic hot electron modulated photoelectric response.Excellent agreements were achieved between experiment and theoretical calculations based on a quantum tunneling model.Such an on-chip combination of plasmonic optics,photoelectric detection and photocatalysis offers promising strategies for next-generation optical gas sensors that require high sensitivity,low time delay,low cost,high portability and flexibility.

Pressure swing adsorption/membrane hybrid processes for hydrogen purification with a high recovery

Hydrogen was recovered and purified from coal gasification-produced syngas using two kinds of hybrid processes： a pressure swing adsorption （PSA）- membrane system （a PSA unit followed by a membrane separation unit） and a membrane-PSA system （a mem- brane separation unit followed by a PSA unit）. The PSA operational parameters were adjusted to control the product purity and the membrane operational parameters were adjusted to control the hydrogen recovery so that both a pure hydrogen product （ 〉 99.9%） and a high recovery （〉 90%） were obtained simultaneously. The hybrid hydrogen purification processes were simulated using HYSYS and the processes were evaluated in terms of hydrogen product purity and hydrogen recovery. For comparison, a PSA process and a membrane separation process were also used individually for hydrogen purifica- tion. Neither process alone produced high purity hydrogen with a high recovery. The PSA-membrane hybrid process produced hydrogen that was 99.98% pure with a recovery of 91.71%, whereas the membrane-PSA hybrid process produced hydrogen that was 99.99% pure with a recovery of 91.71%. The PSA-membrane hybrid process achieved higher total H2 recoveries than the membrane-PSA hybrid process under the same H2 recovery of membrane separation unit. Meanwhile, the membrane-PSA hybrid process achieved a higher total H2 recovery （97.06%） than PSA-membrane hybrid process （94.35%） at the same H2 concentration of PSA feed gas （62.57%）.

Single-cell biomagnifier for optical nanoscopes and nanotweezers

Optical microscopes and optical tweezers,which were invented to image and manipulate microscale objects,have revolutionized cellular and molecular biology.However,the optical resolution is hampered by the diffraction limit;thus,optical microscopes and optical tweezers cannot be directly used to image and manipulate nano-objects.The emerging plasmonic/photonic nanoscopes and nanotweezers can achieve nanometer resolution,but the high-index material structures will easily cause mechanical and photothermal damage to biospecimens.Here,we demonstrate subdiffraction-limit imaging and manipulation of nano-objects by a noninvasive device that was constructed by trapping a cell on a fiber tip.The trapped cell,acting as a biomagnifier,could magnify nanostructures with a resolution of 100 nm(λ/5.5)under white-light microscopy.The focus of the biomagnifier formed a nano-optical trap that allowed precise manipulation of an individual nanoparticle with a radius of 50 nm.This biomagnifier provides a high-precision tool for optical imaging,sensing,and assembly of bionanomaterials.