Pt–Pd bimetallic nanoparticles anchored on uniform mesoporous MnO_(2) sphere as an advanced nanocatalyst for highly efficient toluene oxidation

Improving catalytic performance is a yet still challenge in thermal catalytic oxidation.Herein,uniform mesoporous MnO_(2) nanospheresupported bimetallic Pt–Pd nanoparticles were successfully fabricated via a SiO_(2) template strategy for the total catalytic degradation of volatile organic compounds at low temperature.The introduction of mesopores into the MnO_(2) support induces a large specific surface area and pore size,thus providing numerous accessible active sites and enhanced diffusion properties.Moreover,the addition of a secondary noble metal can adjust the O_(ads)/O_(latt) molar ratios,resulting in high catalytic activity.Among them,the catalyst having a Pt/Pd molar ratio of 7:3 exhibits optimized catalytic activity at a weight hourly space velocity of 36,000 mL g^(-1) h^(-1),reaching 100%toluene oxidation at 175℃ with a lower activation energy(57.0 kJ mol^(-1))than the corresponding monometallic Pt or non-Pt-based catalysts(93.8 kJ mol^(-1) and 214.2 kJ mol^(-1)).Our findings demonstrate that the uniform mesoporous MnO_(2) nanosphere-supported bimetallic Pt–Pd nanoparticles catalyst is an effective candidate for application in elimination of toluene.

A highly dispersed Pt/copper modified-MnO_(2)catalyst for the complete oxidation of volatile organic compounds:The effect of oxygen species on the catalytic mechanism

Manganese oxide(MnO_(2))exhibits excellent activity for volatile organic compound oxidation.However,it is currently unknown whether lattice oxygen or adsorbed oxygen is more conducive to the progress of the catalytic reaction.In this study,novel hollow highly dispersed Pt/Copper modified-MnO_(2)catalysts were fabricated.Cu^(2+)was stabilized into theδ-MnO_(2)cladding substituting original K+,which produced lattice defects and enhance the content of adsorbed oxygen.The 2.03 wt%Pt Cu_(0.050)-MnO_(2)catalyst exhibited the highest catalytic activity and excellent stability for toluene and benzene oxidation,with T_(100)=160℃under high space velocity(36,000 mL g^(-1)h^(-1)).The excellent performance of catalytic oxidation of VOCs is attributed to the abundant adsorbed oxygen content,excellent low-temperature reducibility and the synergistic catalytic effect between the Pt nanoparticles and Cu_(0.050)-MnO_(2).This study provides a comprehensive understanding of the Langmuir-Hinshelwood(L-H)mechanism occurring on the catalysts.

A mini-review on ZnIn_(2)S_(4)-Based photocatalysts for energy and environmental application

As one of the most attractive and eco-friendly technologies,semiconductor photocatalysis is demonstrated as a potential strategy to solve global energy shortage environmental pollution problems.Regarding semiconductor-based photocatalysts,Zinc indium sulfide(ZnIn_(2)S_(4)) with various morphological structures has become research hotspots owing to its superior visible light absorption,high chemical durability and low cost.Nevertheless,the photocatalytic activity of pristine ZnIn_(2)S_(4) is unsatisfactory due to limited range of visible light absorption and fast recombination rate of light-induced electrons and holes.Different modification strategies,such as metal deposition,element doping,vacancy engineering and semiconductor combination,have been systematically developed for enhancing the photocatalytic performance of ZnIn_(2)S_(4) materials.In order to promote further developments of ZnIn_(2)S_(4) in photocatalytic applications,this mini-review summarizes the progress of recent research works for the construction of highly activity ZnIn_(2)S_(4)-based photocatalysts for the first time.In addition,the typical applications of ZnIn_(2)S_(4)-based photocatalytic materials have been critically reviewed and described such as in hydrogen evolution from photocatalytic water splitting,carbon dioxide photoreduction,and treatment of water pollution.The current challenges and further prospects for the development of ZnIn_(2)S_(4) semiconductor photocatalysts are finally pointed out.

GC-MS Analysis of Seeds from Different Pomegranate Varieties

[Objectives]This study aimed to study and analyze the main components of the oil from seeds of 8 different pomegranate varieties.[Methods]The oil in sour and sweet pomegranate seeds was extracted by ultrasonic-assisted method,and the composition of the soil after methyl esterification was identified by GC-MS.[Results]The oil yield of the four sweet pomegranate varieties and the four sour pomegranate varieties ranged from 9.43%-16.97%.A total of 6 compounds were identified in the methyl esterified pomegranate seed oil by GC-MS.[Conclusions]There were no significant differences in oil yield between sweet and sour pomegranate varieties(P>0.05).The content of methyl punicate in the four sweet pomegranate varieties was 52.18%-78.06%,and that in the four sour pomegranate varieties was 78.25%-84.55%.The content of methyl punicate in sour pomegranate was slightly higher than that in sweet pomegranate.

2D/2D hierarchical Co_(3)O_(4)/ZnIn_(2)S_(4)heterojunction with robust builtin electric field for efficient photocatalytic hydrogen evolution

Because of its importance in enhancing charge separation and transfer,built-in electric field engineering has been acknowledged as an effective technique for improving photocatalytic performance.Herein,a stable p–n heterojunction of 2D/2D(2D:twodimensional)Co_(3)O_(4)/ZnIn_(2)S_(4)with a strong built-in electric field is precisely constructed.The Co_(3)O_(4)/ZnIn_(2)S_(4)heterojunction exhibits a higher visible-light photocatalytic hydrogen(H2)evolution rate than the individual components,which is primarily attributed to the synergy effect of improved light absorption,abundant active sites,short charge transport distance,high separation efficiency of photogenerated carriers.Furthermore,the photoelectrochemical studies and density functional theory(DFT)calculation results demonstrate that the enhanced interfacial charge separation and migration induced by the generated built-in electric field are the critical reasons for the boosted photocatalytic performance.This research might pave the way for the rational design and manufacturing of 2D/2D heterojunction photocatalysts with extremely efficient photocatalytic performance for solar energy conversion.

Preparation of Fluorescent Polystyrene via ATRP with Dimethylamino Chalcones as Initiator

4-(3-(4-(Dimethylamino)phenyl)acryloyl)phenyl-2-bromo-2-methylpropanoate(APPBr)was used for the heterogeneous atom transfer radical polymerization(ATRP)of styrene(St)with copper(I)bromide/N,N,N',N",N"-pentamethyldiethylenetriamine(PMDETA)catalytic system.The functional end group was characterized via UV-Vis and ^(1)H NMR spectra.The polymerization showed a first-order kinetic characteristic and each of the obtained polymers had well-controlled molecular weight and relatively low polydispersity index(PDI).Furthermore,the obtained end-functionalized polystyrene(PS)in solution showed strong green-light emission which is further affected by mixing different metal cations.In particular,the fluorescent intensity of the polymer was decreased in the presence of Ag^(+),Cu^(2+)and Fe^(3+).

A review on the rational design and fabrication of nanosized highentropy materials

High-entropy materials are mainly composed of high-entropy alloys(HEAs)and their derivates.Among them,HEAs account for a big part.As a new kind of alloy,they are now arousing great interests because of their high mechanical strength,extraordinary fracture toughness,corrosion resistance compared with traditional alloys.These characteristics allow the use of HEAs in various fields,including mechanical manufacturing,heat-resistant,radiation-resistant,corrosion-resistant,wear-resistant coatings,energy storage,heterocatalysis,etc.In order to promote the extensive application of HEAs,it is of significance to realize their rational design and preparation.In this paper,a systematic review focusing on the rational design and fabrication of nanosized HEAs is given.The design principles of how to match different elements in HEAs and the premise for the formation of single-phase solid solution HEAs are first illustrated.Computation methods for the prediction of formation conditions and properties of HEAs are also in discussion.Then,a detailed description and comparison of the synthesis methods of HEAs and their derivate,as well as their growing mechanism under various synthetic environments is provided.The commonly used characterization methods for the detection of HEAs,along with the typical cases of the application of HEAs in industrial materials,energy storage materials and catalytic materials are also included.Finally,the challenges and perspectives in the design and synthesis of HEAs would be proposed.We hope this review will give guidance for the future development of HEAs materials.

Zeolitic Imidazolate Framework 8-Derived Au@ZnO for Efficient and Robust Photocatalytic Degradation of Tetracycline

Summary of main observation and conclusion Tetracycline (TC) and other antibiotics accumulated in groundwater and soil pollute ecological environment and threaten human health. Gold nan oparticles doped on photocatalysts are able to enhance the photodegradation efficiency during removing these antibiotics, but preparation of Au nanoparticles of well-dispersion on photocatalysts remains challenging. In this work, zeolite imidazolate (ZIF-8) was employed as the precursor to prepare Au@ZnO photocatalyst via impregnation and in-situ reduction method to efficiently degrade the tetracycline in the aqueous solution. Au nanoparticles are of 10 nm in size and uniformly dispersed on the surfaces of ZnO microstructures. The as-prepared Au@ZnO is able to remove 85.5% of TC of 0.010 mg/mL within 2h, presenting higher photocatalytic activity than pure ZnO catalyst. Most importantly, the catalyst shows its superior stability after five cycles without structure and activity changing. The mechanism of the photocatalytic degradation was discussed in detail.

Recent advances in organic-based materials for resistive memory applications

With the rapid development of data-driven human interaction,advanced datastorage technologies with lower power consumption,larger storage capacity,faster switching speed,and higher integration density have become the goals of future memory electronics.Nevertheless,the physical limitations of conventional Si-based binary storage systems lag far behind the ultrahigh-density requirements of post-Moore information storage.In this regard,the pursuit of alternatives and/or supplements to the existing storage technology has come to the forefront.Recently,organic-based resistive memory materials have emerged as promising candidates for next-generation information storage applications,which provide new possibilities of realizing high-performance organic electronics.Herein,the memory device structure,switching types,mechanisms,and recent advances in organic resistive memory materials are reviewed.In particular,their potential of fulfilling multilevel storage is summarized.Besides,the present challenges and future prospects confronted by organic resistive memory materials and devices are discussed.

Synthesis of poly(pyridine-imide)s and their electronic memory performances

In this paper,poly(pyridine-imide)s,PI-Ph and PI-Naphth,were successfully synthesised and fabricated for use as memory devices.The Al/PI-Ph/indium tin oxide(ITO)device showed dynamic random access memory characteristics,whereas Al/PI-Naphth/ITO showed rewritable(FLASH)memory characteristics.Characterisation of their UV,cyclic voltammograms,and density functional theory,were used to illustrate the different memory behaviours.The results show that the stability of electric-field-induced-charge-transfer complexes can affect memory performance.

Design,Synthesis and Characterization of Coordination Polymer from[Cu(DMF)_(4)(SCN)_(2)]as a Precursor

This paper is focused on investigation of coordination polymers constructed by Cu(II)and rigid pyridyl ligands,such as 4,4'-bipyridyl-1,2,4-triazole(Hpytz)and 1,10-phenanthroline(phen)from a mononuclear precursor[Cu(DMF)_(4)(NCS)_(2)](1).As expected,the complex was self-assembled with phen to form a 1D double-stranded chain of[Cu(phen)(μ-SCN)_(2)]∞(2),with Hpytz to form 1D zigzag chain of[Cu_(2)(μ-Hpytz)_(2)(NCS)_(2)(DMF)_(2)(μ-SCN)_(2)]∞(3)in which thiocyanate anion linked the Cu-μ-Hpytz-Cu chain into an infinite 2D network via weak Cu…S interaction.To treat 3 with the bridged anion dca,a novel 3D framework[Cu(μ-Hpytz)(μ-dca)(μ-SCN)]∞(4)was obtained in which Cu-μ-Hpytz-Cu chain is preserved and both thiocyanate anion and dicyanamide(dca)act as bridging ligands.In addition,complex 3 was applied as a metal catalyst in polymerization of MMA in aqueous solution at room temperature.

Negative effect on molecular planarity to achieve organic ternary memory: triphenylamine as the spacer

Adjusting the spacers between the electron-acceptor and the elector-donor is important to design organic ternary memory material but rarely reported. In this paper, two small molecules, ZIPGA and ZIPCAD with benzene ring or triphenylamine as the spacers,were designed and synthesized to fabricate memory devices. The Al/ZIPGA/indium-tin oxide (ITO) device showed ternary characteristics, whereas Al/ZIPCAD/ITO had no obvious memory characteristics. Density functional theory calculation, X-ray diffraction (XRD) and atomic force microscopy (AFM) were employed to interpret the different memory properties. ZIPGA thin film has the closer intermolecular packing and flatter surface morphology than ZIPCAD film, which was favorable to the electron migration. This work demonstrates the importance of spacers and reveals that triphenylamine may be not a good spacer in design of new memory material.

A top–down strategy to realize the synthesis of small-sized L10 - platinum-based intermetallic compounds for selective hydrogenation

The synthesis of Pt-based nanoparticles(NPs)with ultrasmall feature and tailored structure is of great importance for catalysis yet challenging.In this work,we demonstrate a facile top–down strategy for the fabrication of small-sized Pt-based intermetallic compounds(IMCs)with L10 structure through the evaporation of Cd under high temperature.Impressively,such thermal treatment can be used as a versatile strategy for creating binary,ternary,quaternary,quinary,and senary L10-Pt-based IMCs.Moreover,the small-sized Pt-based IMCs display high stability against high temperature of 700℃,which can serve as active and selective catalyst for the selective hydrogenation of 4-nitrophenylacetylene.This work may not only provide a versatile top–down strategy for fabricating highly stable small-sized Pt-based NPs with L10 structure,but also promote their extensive applications in catalysis and beyond.

Application of ion-in-conjugation molecules in resistive memories and gas sensors: The role of conjugation

Ion-in-conjugation(IIC) materials are eme rging as an important class of organic electronic materials with wide applications in energy storage,resistive memories and gas sensors.Many IIC materials were designed and investigated,however the role of conjugation in IIC materials’ performance is yet investigated.Here we designed two molecules obtained by condensation of 4-butylaniline and oxocarbon acid.Squaric acid derivatives squaraine named SA-Bu and a croconamide named CA-Bu which only differ in their oxocarbon cores.While employing SA-Bu and CA-Bu as resistive memory and gas sensory materials,SA-Bu has attained promising performance in ternary memo ry and detection of NO_(2) as low as 10 parts-per-billion whereas CA-Bu show mainly binary memory behavior and negligible NO_(2) response.Theoretical calculations reveal that conjugation of CA-Bu was distorted by the increased steric hindrance,frustrating the charge transport and suppressing the conductivity.Our work demonstrates that the conjugation plays a crucial role in ion-in-materials promoting ternary RRAM devices and highperformance gas sensors manufacture.

Study of Linear and Nonlinear Optical Properties of Four Derivatives of Substituted Aryl Hydrazones of 1,8-Naphthalimide

Four 1,8-naphthalimide hydrazone molecules with different electron-donating groups have been applied in the study of linear and nonlinear optical(NLO)properties.These compounds showed strong green emission in solution.Their NLO properties such as two-photon absorption(TPA)behavior with femtosecond laser pulses ca.800 nm and excited-state absorption(ESA)behavior with nanosecond laser pulses at 532 nm were investigated.Compound 4 presented the largest two-photon cross section(550 GM)among them due to two factors:the conjugated length of compound 4 is the longest and the electron-donating ability of compound 4 is the strongest.Different from TPA behavior,compound 2 showed the best nonlinear absorption properties at 532 nm and its nonlinear absorption coef-ficient and third-order nonlinear optical susceptibilitiesχ^(3)were up to 1.41×10^(−10) MKS and 4.65×10^(−12) esu,re-spectively.Through the modification of the structure,the nonlinear optical properties of these compounds at differ-ent wavelengths(532 and 800 nm)were well tuned.The great broad-band nonlinear optical properties indicate hy-drazones are good candidates for organic nonlinear optical absorption materials.