A Highly Ordered Hydrophilic–Hydrophobic Janus Bi-Functional Layer with Ultralow Pt Loading and Fast Gas/Water Transport for Fuel Cells

One of the critical challenges that limit broad commercialization of proton exchange membrane fuel cells(PEMFC)is to reduce the usage of Pt while maintaining high power output and sufficient durability.Herein,a novel bifunctional layer consisting of vertically aligned carbon nanotubes(VACNTs)and nanoparticles of Pt-Co catalysts(Pt-Co/VACNTs)is reported for highperformance PEMFCs.Readily prepared by a two-step process,the Pt-Co/VACNTs layer with a hydrophilic catalyst-loaded side and a hydrophobic gas diffusion side enables a PTFE-free electrode structure with fully exposed catalyst active sites and superior gas–water diffusion capability.When tested in a PEMFC,the bi-functional Pt-Co/VACNTs layer with ultralow Pt loading(~65μgcathodecm-2)demonstrates a power density of 19.5 kW gPt cathode-1 at 0.6 V,more than seven times that of a cell with commercial Pt/C catalyst(2.7 kW gPt cathode-1 at 0.6 V)at a loading of 400μgcathodecm-2 tested under similar conditions.This remarkable design of VACNTs-based catalyst with dual functionalities enables much lower Pt loading,faster mass transport,and higher electrochemical performance and stability.Further,the preparation procedure can be easily scaled up for low-cost fabrication and commercialization.

3D hollow sphere Co_3O_4/MnO_2-CNTs:Its high-performance bi-functional cathode catalysis and application in rechargeable zinc-air battery

There has been a continuous need for high active, excellently durable and low-cost electrocatalysts for rechargeable zinc-air batteries. Among many low-cost metal based candidates, transition metal oxides with the CNTs composite have gained increasing attention. In this paper, the 3-D hollow sphere MnO_2 nanotube-supported Co_3O_4 nanoparticles and its carbon nanotubes hybrid material(Co_3 O_4/MnO_2-CNTs) have been synthesized via a simple co-precipitation method combined with post-heat treatment. The morphology and composition of the catalysts are thoroughly analyzed through SEM, TEM, TEM-mapping, XRD, EDX and XPS. In comparison with the commercial 20% Pt/C, Co_3O_4/MnO_2,bare MnO_2 nanotubes and CNTs, the hybrid Co_3O_4/MnO_2-CNTs-350 exhibits perfect bi-functional catalytic activity toward oxygen reduction reaction and oxygen evolution reaction under alkaline condition(0.1 M KOH). Therefore, high cell performances are achieved which result in an appropriate open circuit voltage(～1.47 V),a high discharge peak power density(340 mW cm^(-2)) and a large specific capacity(775 mAh g^(-1) at 10 mA cm^(-2)) for the primary Zn-air battery, a small charge-discharge voltage gap and a high cycle-life(504 cycles at 10 mA cm^(-2) with 10 min per cycle) for the rechargeable Zn-air battery. In particular, the simple synthesis method is suitable for a large-scale production of this bifunctional material due to a green, cost effective and readily available process.

Ultrasmall AuPd nanoclusters on amine-functionalized carbon blacks as high-performance bi-functional catalysts for ethanol electrooxidation and formic acid dehydrogenation

The synthesis of ultrasmall metal nanoclusters(NCs) with high catalytic activities is of great importance for the development of clean and renewable energy technologies but remains a challenge. Here we report a facile wet-chemical method to prepare ~1.0 nm Au Pd NCs supported on amine-functionalized carbon blacks. The Au Pd NCs exhibit a specific activity of 5.98 mA cm_(AuPd)^(-2)and mass activity of 5.25 A mg_(auPd)^(-1) for ethanol electrooxidation, which are far better than those of commercial Pd/C catalysts(1.74 mAcm_(AuPd)^(-2) and 0.54 A mg_(Pd)^(-1) ). For formic acid dehydrogenation, the Au Pd NCs have an initial turn over frequency of 49339 h^(-1) at 298 K without any additive, which is much higher than those obtained for most of reported Au Pd catalysts. The reported synthesis may represent a facile and low-cost approach to prepare other ultrasmall metal NCs with high catalytic activities for various applications.

Structural Design and Property Characterization of Bi-functional Photorefractive Polymer

A novel bi-functional photorefractive acrylate polymer with pendant carbazolyl groups and azo derivatives as side chains was synthesized. Photorefractive experiments showed a high two-beam coupling gain coefficient of 93 cm(-1), diffraction efficiency of 12% and electro-optic coefficient of 26 pm/V were obtained.

Photorefractivity in a Bi-functional Polymer Nanocomposites Sensitized by CdS Nanoparticle

We report an organic/inorganic hybridized nanocomposite consisting of a bi-functional poly（N-vinyl）-3-[p-nitrophenylazo]carbazolyl serves as a polymeric charge-transporting and second-order nonliner optical matrix, and CdS nanoparticles as photosensitizers to manifest photorefractive （PR） effect. The unpoled PVNPAK film exhibits a second harmonic generation （SHG） coefficient of 4.7 pm/V due to the possibility of self-alignment of the azo chromophore. Significant enhancement of photoconductivity is noticed with the increase of CdS nanoparticles concentration. The photorefractive property of the polymer nanocomposites were determined by two-beam coupling （TBC） experiment. The TBC gain and diffraction efficiency of 11.89 cm-1 and 3.2% were obtained for PVNPAK/CdS at zero electrical field.

Particle agglomeration and inhibition method in the fluidized pyrolysis reaction of waste resin

This work investigated the pyrolysis reaction of waste resin in a fluidized bed reactor.It was found that the pyrolysis-generated ash would adhere to the surface of ceramic particles,causing particle agglomeration and defluidization.Adding kaolin could effectively inhibit the particle agglomeration during the fluidized pyrolysis reaction through physical isolation and chemical reaction.On the one hand,kaolin could form a coating layer on the surface of ceramic particles to prevent the adhesion of organic ash generated by the pyrolysis of resin.On the other hand,when a sufficient amount of kaolin(-0.2%(mass))was added,the activated kaolin could fully contact with the Na+ ions generated by the pyrolysis of resin and react to form a high-melting aluminosilicate mineral(nepheline),which could reduce the formation of low-melting-point sodium sulfate and thereby avoid the agglomeration of ceramic particles.

New Kinetic Computerized Model for Multicomponent Mass Transfer in Bi-Functional Matrix of NanoComposites

The aim of this theoretical investigation is the description of the multicomponent mass transfer process in the Nano- Composites (NC)—novel materials with the bi-functional matrix. The new theoretical NC Model is assigned for the modern theoretical investigations of the multicomponent mass transfer kinetics in the bi-functional NC materials. This NC Model for the multicomponent mass transfer in the bi-functional NC matrix includes into the consideration the proposed key conception—two co-existing routes: I—chemical reactions onto the active NC centers-sites, and II—diffusion mass transfer inside the bi-functional NC matrix. All the results are presented in the terms of the additional key concept: propagating multicomponent concentration waves (W+) in the NC matrix. The used W+ concept for the description of the multicomponent NC mass transfer kinetics give the clear interpretation of the computerized results. The mass transfer process in the NC matrix has been described theoretically by computerized simulation. The results of the calculations are new and illustrated by author’s animations showing visually the propagation of the multicomponent concentration waves (W) inside the various NC matrixes: r-beads, cylindrical ro-fibers, or planar L-membranes. Two variants of modeling for mass transfer diffusion kinetics in the bi-functional NC matrixes with one (Variant 1), or two (Variant 2) dissociation-association reactions at the active nano-sites (R0) are considered theoretically.

A functionalized activated carbon adsorbent prepared from waste amidoxime resin by modifying with H_(3)PO_(4) and ZnCl_(2) and its excellent Cr(Ⅵ)adsorption

With the application of resins in various fields, numerous waste resins that are difficult to treat have been produced. The industrial wastewater containing Cr(Ⅵ) has severely polluted soil and groundwater environments, thereby endangering human health. Therefore, in this paper, a novel functionalized mesoporous adsorbent PPR-Z was synthesized from waste amidoxime resin for adsorbing Cr(Ⅵ). The waste amidoxime resin was first modified with H3PO4 and ZnCl_(2), and subsequently, it was carbonized through slow thermal decomposition. The static adsorption of PPR-Z conforms to the pseudo-second-order kinetic model and Langmuir isotherm, indicating that the Cr(Ⅵ) adsorption by PPR-Z is mostly chemical adsorption and exhibits single-layer adsorption. The saturated adsorption capacity of the adsorbent for Cr(Ⅵ) could reach 255.86 mg/g. The adsorbent could effectively reduce Cr(Ⅵ) to Cr(Ⅲ) and decrease the toxicity of Cr(Ⅵ) during adsorption. PPR-Z exhibited Cr(Ⅵ) selectivity in electroplating wastewater. The main mechanisms involved in the Cr(Ⅵ) adsorption are the chemical reduction of Cr(Ⅵ) into Cr(Ⅲ) and electrostatic and coordination interactions. Preparation of PPR-Z not only solves the problem of waste resin treatment but also effectively controls Cr(Ⅵ) pollution and realizes the concept of “treating waste with waste”.

Effect of benzoxazine resin on mechanical properties of nitrile rubber composites: Experiment and molecular simulation

Benzoxazine resin,being a new type of phenolic resin deve-loped to overcome the shortcomings of traditional phenolic resins,has been synthesized from phenol,formaldehyde and amine,and does not require solvent elimination or monomer purification to obtain a relatively clean precursor.It has potential application in the field of aerospace due to its low expansion coefficient,high weather resistance,high carbon yield,good mechanical strength,and excellent ablation resistance[1].It can be mixed with various other resins or polymers to produce new resins with a broad range of applications[2-3].

Cardo poly (ether sulfone) toughened E51/DETDA epoxy resin and its carbon fiber composites

A toughener that can effectively improve the interlaminar toughness in carbon fiber composites is crucial for various applications.We investigated,the toughening effects of phenolphthalein-based cardo poly(ether sulfone)(PES-C)on E51/DETDA epoxy and its carbon fiber composites(CFCs).Scanning electron microscopy showed that the phase structures of PES-C/epoxy blends change from island(of dispersed phase)structures to bi-continuous structures(of the matrix)as the PES-C content increased,which is associated with reaction-induced phase separation.After adding 15 phr PES-C,the glass transition temperature(T_(g))of the blends increased by 51.5℃,and the flexural strength,impact strength and fracture toughness of the blends were improved by 41.1%,186.2%and 42.7%,respectively.These improvements could be attributed to the phase separation structure of the PES-C/epoxy sys-tem.A PES-C film was used to improve the mode-II fracture toughness(G_(IIC))of CFCs.The G_(IIC) value of the 7μm PES-C film toughened laminate was improved by 80.3%compared to that of the control laminate.The increase in G_(IIC) was attributed to cohesive failure and plastic deformation in the interleaving region.

Effect of Epoxy Resin on the Properties of Recycled Asphalt

To promote the recycling of reclaimed asphalt pavement(RAP),epoxy resin was used to prepare the epoxy-recycled asphalt mixtures.The effect of epoxy resin on the properties of aged asphalt binder was investigated based on the tensile test,flexural creep test,and laser scanning confocal microscopy.The curing characteristics and the mechanical performance of recycled asphalt with different epoxy contents were explored.The results show that the low-temperature performance,ductility,and strength of the aged asphalt binder were significantly improved when the epoxy content reached 40%.The curing time of epoxy-recycled asphalt should be at least 4 d to ensure the formation of good internal spatial network structure.

B-COPNA resin formation from ethylene tar light fractions:Process development and mechanical exploration by molecular simulation

An efficient utilization strategy of ethylene tar(ET),the main by-product of the ethylene cracking unit,is urgently required to meet demands for modern petrochemical industry.On the other hand,condensed polynuclear aromatic resin of moderate condensation degree(B-COPNA)is a widely used carbon material due to its superb processability,the production of which is,however,seriously limited by the high cost of raw materials.Under such context,an interesting strategy was proposed in this study for producing B-COPNA resin using crosslinked light fractions of ethylene tar(ETLF,boiling point<260℃)facilitated by molecular simulation.1,4-Benzenedimethanol(PXG)was first selected as the crosslinking agent according to the findings of molecular simulation.The effects of operating conditions,including reactions temperature,crosslinking agent,and catalyst content on the softening point and yield of B-COPNA resin products were then investigated to optimize the process.The reaction mechanism of resin production was studied by analyzing the molecular structure and transition state of ETLF and crosslinking agents.It was shown that PXG exhibited a superior capacity of withdrawing electrons and a higher electrophilic reactivity than other crosslinking agents.In addition to the highest yield and greatest heat properties,PXG-prepared resin contained the most condensed aromatics.The corresponding optimized conditions of resin preparation were 180℃,1:1.9(PXG:ETLF),and 3%(mass)of catalyst content with a resin yield of 78.57%.It was the electrophilic substitution reaction that occurred between the ETLF and crosslinking agent molecules that were responsible for the resin formation,according to the experimental characterization and molecular simulation.Hence,it was confirmed that the proposed strategy and demonstrated process can achieve a clean and high value-added utilization of ETLF via B-COPNA resin preparation,bringing huge economic value to the current petrochemical industry.

Kinetics and Mechanism of Hydration of Acrylic Acid over Ion-exchanged Resin:Experimental Exploration and DFT Calculation

Liquid-phase acrylic acid hydration over solid-phase catalysts is a key reaction for the industrial productionof 3-hydroxypropionic acid. However, the relevant literature primarily focuses on the experimental aspects of catalystscreening and exploring reaction conditions, with few accurate descriptions of the reaction kinetics and determination ofthe reaction mechanism. Here, we combined kinetics experiments and theoretical calculations to elucidate the kinetics andmechanism of acrylic acid hydration on a resin catalyst. The pseudo-homogeneous model, and Langmuir-Hinshelwood-Haugen-Watson and Elie-Riedel (ER) heterogeneous models were used to explain the experimental kinetics data. TheER model can explain the experimental data very well, suggesting strong adsorption of acrylic acid on the surface of theresin catalyst. Furthermore, density functional theory calculations show that the hydration follows a stepwise, rather than aconcerted, reaction pathway. The present study provides theoretical insights into the reaction mechanism and kinetics, fillingthe gap in our understanding of the reaction on a fundamental level.

Curing kinetics and plugging mechanism of high strength curable resin plugging material

Lost circulation, a recurring peril during drilling operations, entails substantial loss of drilling fluid and dire consequences upon its infiltration into the formation. As drilling depth escalates, the formation temperature and pressure intensify, imposing exacting demands on plug materials. In this study, a kind of controllable curing resin with dense cross-network structure was prepared by the method of solution stepwise ring-opening polymerization. The resin plugging material investigated in this study is a continuous phase material that offers effortless injection, robust filling capabilities, exceptional retention, and underground curing or crosslinking with high strength. Its versatility is not constrained by fracture-cavity lose channels, making it suitable for fulfilling the essential needs of various fracture-cavity combinations when plugging fracture-cavity carbonate rocks. Notably, the curing duration can be fine-tuned within the span of 3-7 h, catering to the plugging of drilling fluid losing of diverse fracture dimensions. Experimental scrutiny encompassed the rheological properties and curing behavior of the resin plugging system, unraveling the intricacies of the curing process and establishing a cogent kinetic model. The experimental results show that the urea-formaldehyde resin plugging material has a tight chain or network structure. When the concentration of the urea-formaldehyde resin plugging system solution remains below 30%, the viscosity clocks in at a meager 10 mPa·s. Optimum curing transpires at 60℃, showcasing impressive resilience to saline conditions. Remarkably, when immersed in a composite saltwater environment containing 50000 mg/L NaCl and 100000 mg/L CaCl_(2), the urea-formaldehyde resin consolidates into an even more compact network structure, culminating in an outstanding compressive strength of 41.5 MPa. Through resolving the correlation between conversion and the apparent activation energy of the non-isothermal DSC curing reaction parameters, the study attests to the fulfillment of the kinetic equation for the urea-formaldehyde resin plugging system. This discerning analysis illuminates the nuanced shifts in the microscopic reaction mechanism of the urea-formaldehyde resin plugging system. Furthermore, the pressure bearing plugging capacity of the resin plugging system for fractures of different sizes is also studied. It is found that the resin plugging system can effectively resident in parallel and wedge-shaped fractures of different sizes, and form high-strength consolidation under certain temperature conditions. The maximum plugging pressure of resin plugging system for parallel fractures with outlet size 3 mm can reach 9.92 MPa, and the maximum plugging pressure for wedge-shaped fractures with outlet size 5 mm can reach 9.90 MPa. Consequently, the exploration and application of urea-formaldehyde resin plugging material precipitate a paradigm shift, proffering novel concepts and methodologies in resolving the practical quandaries afflicting drilling fluid plugging.

Enhanced corrosion resistance of epoxy resin coating via addition of CeO_(2) and benzotriazole

The use of fillers to enhance the corrosion protection of epoxy resins has been widely applied.In this work,cerium dioxide(CeO_(2))and benzotriazole(BTA)were introduced into an epoxy resin to enhance the corrosion resistance of Q235 carbon steel.Scanning electron microscopy results indicated that the CeO_(2) grains were rod-like and ellipsoidal in shape,and the distribution pattern of BTA was analyzed by energy dispersive spectroscope.The dynamic potential polarization curve proved the excellent corrosion resistance of the composite epoxy resin with CeO_(2) and BTA co-addition,and electrochemical impedance spectroscopy test analysis indicated the significantly enhanced long-term corrosion protection performance of the composite coating.And the optimal protective performance was provided by the coating containing 0.3%(mass)CeO_(2) and 20%(mass)BTA,which was attributed to the barrier performance of CeO_(2) particles and the chemical barrier effect of BTA.The formation of corrosion products was analyzed using X-ray diffraction.In addition,the corrosion resistance mechanism of the coating was also discussed in detail.

Preparation of Environmentally Friendly Urea-Hexanediamine-Glyoxal(HUG)Resin Wood Adhesive

Using non-toxic,low-volatile glyoxal to completely replace formaldehyde for preparing urea-glyoxal(UG)resin adhesive is a hot research topic that could be of great interest for the wood industry.However,urea-glyoxal(UG)resins prepared by just using glyoxal instead of formaldehyde usually yields a lower degree of polymerization.This results in a poorer bonding performance and water resistance of UG resins.A good solution is to pre-react urea to preform polyurea molecules presenting already a certain degree of polymerization,and then to condense these with glyoxal to obtain a novel UG resin.Therefore,in this present work,the urea was reacted with hexamethylene diamine to form a polyurea named HU,and then this was used to react it with different amounts of glyoxal to synthesize hexamethylenediamine-urea-glyoxal(HUG)polycondensation resins,and to use this for bonding plywood.The results show that the glyoxal can well react with HU polyuria via addition and schiff base reaction,and also the HUG resin exhibits excellent bonding strength and water resistance.The shear strength of the plywood bonded with this HUG at 160°C hot press temperature as high as 1.93 MPa,2.16 MPa and 1.61 MPa,respectively,which meets the requirement of the China national standard GB/T 9846-2015(≥0.7 MPa),and can be a good choice as a wood adhesive for industrial application.

Optimization Mechanism of Mechanical Properties of Basalt Fiber-Epoxy Resin Composites by Interfacially Enriched Distribution of Nano-Starch Crystals

Fibre reinforced polymer composites have become a new generation of structural materials due to their unique advantages such as high specific strength,designability,good dimensional stability and ease of large-area monolithic forming.However,the problem of interfacial bonding between the resin matrix and the fibres limits the direct use of reinforcing fibres and has become a central difficulty in the development of basalt fibre-epoxy composites.This paper proposes a solution for enhancing the strength of the fibre-resin interface using maize starch nanocrystals,which are highly yield and eco-friendly.Firstly,in this paper,corn starch nanocrystals(SNC)were prepared by hydrolysis,and were deposited on the surface of basalt fibers by electrostatic adsorption.After that,in order to maximize the modification effect of nano-starch crystals on the interface,the basalt fiber-epoxy resin composite samples were prepared by mixing in a pressureless molding method.The test results shown that the addition of basalt fibers alone led to a reduction in the strength of the sample.Deposition of 0.1 wt%SNC on the surface of basalt fibers can make the strength consistent with pure epoxy resin.When the adsorption amount of SNC reached 0.5 wt%,the tensile strength of the samples was 23.7%higher than that of pure epoxy resin.This is due to the formation of ether bond homopolymers between the SNC at the fibre-epoxy interface and the epoxy resin,which distorts the originally smooth interface,leading to increased stress concentration and the development of cracks.This enhances the binding of basalt fibers.The conclusions of this paper can provide an effective,simple,low-cost and non-polluting method of interfacial enhancement modification.

Adsorption behaviors and mechanisms of gold recovery from thiosulfate solution by ion exchange resin

The adsorption behaviors and mechanisms of gold from thiosulfate solution on strong-base anion exchange resin were systematically investigated.The comparison experiment of adsorption ability and selectivity for gold showed that gel Amberlite IRA-400 resin with Type Ⅰ quaternary ammonium functional group had better adsorption performance.The increases of resin dosage,ammonia concentration and solution pH were favorable to gold adsorption,whereas the rises of cupric and thiosulfate concentrations were disadvantageous to gold loading.Microscopic characterization results indicated that gold was adsorbed in the form of [Au(S_(2)O_(3))_(2)]^(3–) complex anion by exchanging with the counter ion Cl^(–) in the functional group of the resin.Density functional theory calculation result manifested that gold adsorption was mainly depended on the hydrogen bond and van der Waals force generated between O atom in [Au(S_(2)O_(3))_(2)]^(3–) and H atom in the quaternary ammonium functional group of the resin.

Evaluating two stages of silicone-containing arylene resin oxidation via experiment and molecular simulation

Silicon-containing aryl acetylene resin(PSA)is a new type of high-temperature resistant resin with excellent oxidation resistance,whereas antioxidant reaction mechanism of PSA resin under ultra-high temperatures still remains unclear.Herein,the oxidation behavior and mechanisms of PSA resin are systematically investigated combining kinetic analysis and Reax FF molecular dynamics(MD)simulations.Thermogravimetric analysis indicates that the oxidation process of PSA resin undergoes two main steps:oxidative mass gain and oxidative degradation.The distributed activation energy model(DAEM)is employed for describing oxidation processes and the best-fit one is obtained using genetic algorithms and differential evolution.DAEM model demonstrates that the oxidative weight gain stage is dominated by two virtual reactants and the oxidative degradation stage consists of three virtual reactants.Correspondingly,the observation of MD reaction pathways indicates that oxygen oxidation of unsaturated structures occurs in the initial stage,which results in the formation of PSA resin oxides.Furthermore,cracked pieces react with O_(2)to generate CO and other chemicals in the second step.The resin matrix's great antioxidation resilience is illustrated by the formation of SiO_(2).The analysis based on MD simulations exhibits an efficient computational proof with the experiments and DAEM methods.Based on the results,a two-stage reaction mechanism is proposed,which provides important theoretical support for the subsequent study of the oxidation behavior of silica-based resins.

Preparation and Swelling Kinetic Analysis of Poly (HPMC-co-AA-co-AM) Super Absorbent Resin

Super absorbent resin(SAR)is prepared by aqueous high temperature polymerization using hydroxypropyl methylcellulose(HPMC)as monomer backbone material,acrylic acid(AA)and acrylamide(AM)as the graft copolymer monomer,potassium persulfate(KPS)as the initiator to generate free radicals,and N,N`-methylenebisacrylamide(MBA)as cross-linking agent for cross-linking reaction.Simutaneously,the influence of individual factors on the water absorption is investigated,and these factors are mainly AA,AM,KPS,MBA,HPMC,and reaction temperature.The optimized conditions are obtained by the experiment repeating for several times.The water absorption multiplicity and salt absorption multiplicity under the conditions are 782.4 and 132.5 g/g,respectivity.Furthermore,the effects of different temperatures and salt concentrations on its water absorption,as well as the swelling kinetics of SAR are studied.It is indicated the water-absorbing swelling process is mainly caused by the difference in water osmotic pressure and Na+concentration inside and outside the cross-linked molecular structure of the resin,which is not only consistent with the quasi-secondary kinetic model,but also with the Fick diffusion model.