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Catalytic hydrodeoxygenation (HDO) is one of the most promising strategies to transform oxygen-rich biomass derivatives into high value-added chemicals and fuels, but highly challenging due to the lack of highly efficient nonprecious metal catalysts. Herein, we report for the first time of a facile synthetic approach to controllably fabricate well-defined Ni-Co alloy NPs confined on the tip of N-CNTs as HDO catalyst. The resultant Ni-Co alloy catalyst possesses outstanding HDO performance towards biomass-derived vanillin into 2-methoxy-4-methylphenol in water with 100% conversion efficiency and selectivity under mild reaction conditions, surpassing the reported high performance nonprecious HDO catalysts. Impressively, our experimental results also unveil that the Ni-Co alloy catalyst can be generically applied to catalyze HDO of vanillin derivatives and other aromatic aldehydes in water with 100% conversion efficiency and over 90% selectivity. Importantly, our DFT calculations and experimental results confirm that the achieved outstanding HDO catalytic performance is due to the greatly promoted selective adsorption and activation of C=O, and desorption of the activated hydrogen species by the synergism of the alloyed Ni-Co NPs. The findings of this work affords a new strategy to design and develop efficient transition metal-based catalysts for HDO reactions in water.

Exotic domain-wall phenomena make ferroelectrics the candidates for nanoelectronics. The local symmetry and structure anomalies at domain walls have raised interest in the unusual functionalities, such as domain wall chirality and conductivity. Especially, the spontaneous lattice distortion and symmetry breaking at domain walls activate them as the location of structural transformation. However, the routes to achieve ferroelectric-antiferroelectric phase transition via ferroelectric domain walls remain challenging, which are important to develop materials for energy storage and conversion. Here, we have observed stepwise antiferroelectric phase transition in strained pure BiFeO3 ultrathin films derived from ferroelectric domain walls. Aberration-corrected transmission electron microscopy observation reveals that the resultant phase transition is mediated by dense 180° domain walls via providing the antiparallel cation displacement, cooperating with the enhanced interfacial oxygen octahedral clamping. First-principles calculations further confirm the critical role of interfacial oxygen octahedral coupling during this transition. These findings report an alternative route for antiferroelectric phase transition. Besides, our results provide fresh insights into functionalities of ferroelectric domain walls and open a venue for developing energy-storage materials based on domain engineering.

Developing high‐performance heterogeneous catalysts for one‐pot reductive amination reactions is critically important for pharmaceutical and agrochemical synthetic industries. In this work, N‐doped carbon nanotubes supported CoPt alloy decorated Co nanoparticles (NPs) are successfully fabricated. As a consequence, the resultant catalyst exhibits desirable activity, selectivity and stability toward the one‐pot synthesis of imines. More importantly, the extensive experimental studies and density function theory (DFT) calculations results reveal that the high catalytic activity of the catalyst is mainly due to the co‐existence of CoPt alloy NPs and Co NPs with Co−Nx active sites. The high selectivity of imines could be ascribed to the following aspects: (1) competitively preferred adsorption of nitroarenes to avoid side‐hydrogenation of aldehydes; (2) weakened adsorption of imines to minimize its over‐hydrogenation. This work may provide a promising direction and strategy to design high‐performance reductive amination catalysts for industrial applications.

Retention failure is deleterious on ferroelectric domain stability, resulting in data loss in ferroelectric memories. However, the understanding of the origin of retention failure remains a challenge for the lack of a direct experimental evidence. Here, using a combination of piezoelectric force microscopy, atomic-scale scanning transmission electron microscopy and reciprocal space mapping, we report that the polarization retention failure is caused by a strain gradient induced flexoelectric field in tetragonal ferroelectric films. Atomic imaging reveals that the strain gradient is introduced by tensile strains, which is resultant from the vertically distributed Pb-rich anti-phase domains. This strain gradient couples with polarizations and results in flexoelectric fields in the films, leading to the retention failure in the films. Our study directly underlines the atomic mechanisms behind the strain gradient induced macroscopic retention failure behavior and clarifies the effect of local strain state on domain relaxation processes, thus can shed light on further understanding and improving the retention properties of oxide ferroelectrics.

Phase coexistence in ferroelectric oxide films displays complex phase competitions and transformation which suggest new multiple-coupled properties. Here we have successfully engineered the coexistence of flux-closure and a1/a2 phases in tensile-strained PbTiO3 films sandwiched between GdScO3 substrate and a SrTiO3 layer. Moreover, by using in-situ electron beam illumination, the unusual transformation from a1/a2 phase to the flux-closure phase was directly observed. In detail, there are two types of transformations: One is the nucleation, growth, and expansion of the flux-closure phase from the internal region of the a1/a2 phase. The other feature is a “dislocation gliding” like behavior: a thin lamella of a1/a2 shrinks like “partial dislocation pairs” and finally the gradually disappeared a1/a2 lamella forms a “perfect dislocation” in the flux-closure domain matrix. Phase-field simulations suggest that the a1/a2 to flux-closure transition is induced by the decrease of the depolarization field, which is screened by the injected electrons from electron beam irradiation. These results directly confirm the phase interconversion under an external stimulus at the nanometer scale, which shed new light on the fabrication of new polar textures.

A topological meron features a non-coplanar structure, whose order parameters in the core region are perpendicular to those near the perimeter. A meron is half of a skyrmion, and both have potential applications for information carrying and storage. Although merons and skyrmions in ferromagnetic materials can be readily obtained via inter-spin interactions, their behaviour and even existence in ferroelectric materials are still elusive. Here we observe using electron microscopy not only the atomic morphology of merons with a topological charge of 1/2, but also a periodic meron lattice in ultrathin PbTiO3 films under tensile epitaxial strain on a SmScO3 substrate. Phase-field simulations rationalize the formation of merons for which an epitaxial strain, as a single alterable parameter, plays a critical role in the coupling of lattice and charge. This study suggests that by engineering strain at the nanoscale it should be possible to fabricate topological polar textures, which in turn could facilitate the development of nanoscale ferroelectric devices. Merons are topological structures, but these have yet to be directly observed in ferroelectrics. Here, by epitaxially straining PbTiO3 on a SmScO3 substrate, electron microscopy and phase-field modelling allow the morphology and distribution of merons to be observed.

Single‐atom catalysts have demonstrated their superiority over other types of catalysts for various reactions. However, the reported nitrogen reduction reaction single‐atom electrocatalysts for the nitrogen reduction reaction exclusively utilize metal–nitrogen or metal–carbon coordination configurations as catalytic active sites. Here, we report a Fe single‐atom electrocatalyst supported on low‐cost, nitrogen‐free lignocellulose‐derived carbon. The extended X‐ray absorption fine structure spectra confirm that Fe atoms are anchored to the support via the Fe‐(O‐C2)4 coordination configuration. Density functional theory calculations identify Fe‐(O‐C2)4 as the active site for the nitrogen reduction reaction. An electrode consisting of the electrocatalyst loaded on carbon cloth can afford a NH3 yield rate and faradaic efficiency of 32.1 μg h−1 mgcat.−1 (5350 μg h−1 mgFe−1) and 29.3 %, respectively. An exceptional NH3 yield rate of 307.7 μg h−1 mgcat.−1 (51 283 μg h−1 mgFe−1) with a near record faradaic efficiency of 51.0 % can be achieved with the electrocatalyst immobilized on a glassy carbon electrode.

Ferroelectrics exhibit polarization tunable resistance switching behaviors, which are promising for next-generation non-volatile memory devices. For technological applications, thinner nanoscale arrays are expected, which feature with higher density and larger ON/OFF (RON/OFF) ratios in the metal/ferroelectrics/semiconductor heterojunction. Here, we acquire high density BiFeO3 (BFO) nano-islands around 10 nm in thickness displaying a high RON/OFF ratio of 103, comparable to the tunnel junctions. Moreover, both the macroscopic and microscopic resistive switching behaviors of the present BiFeO3 films reveal an unexpected the filamentary-type resistive switching which is modified by the charged domain walls in nano-islands dominated by the center-type domains. Particularly, the charged domain walls spontaneously formed within the BFO nano-islands are proposed as the conductive paths based on the redistribution of carriers under the applied voltages. Potential applications for memories with large RON/OFF ratios of such kind of configurable charged domain walls are demonstrated.

Borophene has emerged as a type of two-dimensional monoelemental nanomaterials with excellent drug loading capacity and photothermal properties. Here, we demonstrated the adsorption of plasma proteins onto borophene nanosheets (B NSs) and the promoted immune responses of macrophage by the B NS-corona complex. We discovered that plasma proteins changed the surface identities of B NSs. Using proteomics analysis, 46.5% of the proteins bound to B NSs (94 plasma proteins) were immune-relevant proteins. Uptake of B NSs by phagolysosomes was observed, and the plasma corona promoted the uptake. In comparison with graphene and phosphorene, we found that 32 plasma proteins appeared on all of the three nanosheets. The proportion of immune-relevant proteins in graphene-corona and phosphorene-corona was 41.3% and 75.6%, respectively. The components of the adsorbed immune-relevant proteins show diversity, which influence the immune responses of these nanosheets. Phosphorene-corona showed the most remarkable immunoregulatory behavior in these nanosheets. For the first time, we compared the highly complex protein corona at the nanosheet-plasma interface of three key 2D monoelemental nanosheets. Our study helps to understand the interaction between borophene and biological systems and provides a theoretical basis for the development and application of borophene in the biomedical field.

Electrochemical N2 reduction to NH3 has been considered as a promising sustainable and clean process to replace the conventional Haber–Bosch process. However, the development of efficient and stabl...

Anion vacancy defect-engineered catalysts have exhibited impressive activity in the electro/photocatalytic N2 reduction reaction (NRR) because of their advantages in N2 adsorption and activation. However, most studies have concentrated on oxygen vacancy defects because of their low formation energy. Sulfur, nitrogen, and phosphorus anion vacancy defects with higher formation energies are rarely reported. Herein, utilizing a doped-oxygen-induced strategy, partially electrochemically reduced oxygen-doped Cu3P nanosheets (RO-Cu3P) with rich surface phosphorus vacancies were successfully synthesized and could be employed as highly catalytically active species for the electrochemical NRR process. It is noteworthy that both ammonia and hydrazine were detected in the NRR tests, indicating that the reduction process followed a proposed alternating pathway. An ammonia yield of 28.12 μg h−1 cm−2 with a high faradaic efficiency of 17.5% was achieved under ambient conditions for the RO-Cu3P/CFC electrode with abundant phosphorus vacancies, about 3.4 times higher than that for a prepared pure Cu3P/CFC electrode. It is believed that the RO-Cu3P species with abundant surface phosphorus vacancies are the most likely active species for NRR, as confirmed by both control experiments and density functional theory calculations. This work provides a promising strategy to design and construct efficient NRR catalysts with anion vacancy defects for good theoretical and experimental guidance.

This work reports the synthesis of core-shell structured Au@C composite through a simple one-step laser ablation technique. The results demonstrate that the Au@C with a mean nanosphere size of ∼8.0 nm is composed of a spherical shaped Au core and 1-2 layered graphitic carbon shell with abundant defects. As a nitrogen reduction reaction (NRR) electrocatalyst, the Au@C gives a large NH

Copper-indium-gallium-selenide (CIGS) alloys are successfully applied in thin-film solar cells. For a better use of the solar spectrum, they also offer the possibility of multijunction devices by tuning the composition in the different layers. As-grown CIGS is intrinsically p-type due to copper vacancies (${V}_{\mathrm{Cu}}$), but n-type doping is also useful for applications. While ${\mathrm{Cu}\mathrm{In}\mathrm{Se}}_{2}$ can be easily turned n-type, ${\mathrm{Cu}\mathrm{Ga}\mathrm{Se}}_{2}$ cannot, and this represents a problem, because increasing the band gap of CIGS requires a high $\mathrm{Ga}/\mathrm{In}$ ratio. Investigating the effect of hydrogen on ${\mathrm{Cu}\mathrm{Ga}\mathrm{Se}}_{2}$ by an optimized hybrid functional, we show that hydrogenation from an atomic source as, e.g., by a hydrogen plasma treatment, can turn the material n-type due to the formation of shallow donor ${V}_{\mathrm{Cu}}+2\mathrm{H}$ complexes, while ${\mathrm{H}}_{2}$ implantation, producing an internal hydrogen reservoir, can be used to produce semi-insulating material. We also show that under normal process conditions, unintentional hydrogen incorporation does not have a significant effect on ${\mathrm{Cu}\mathrm{Ga}\mathrm{Se}}_{2}$.

In this study, a nanocube of zeolitic imidazolate framework-67 (ZIF-67) was prepared by blending cobalt nitrate hexahydrate and 2-methylimidazole together in aqueous solutions containing hexadecyltrimethylammonium bromide (CTAB). Then, grapheme oxide (GO) wrapped ZIF-67 nanocomposites (ZIF-67/GO-n) were prepared by one-pot stirring method at room temperature. The morphology and microstructure of ZIF-67 and its GO nanocomposites were investigated by Raman spectra, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) specific surface area analysis. Electrochemical capacitance properties of all samples were characterized by cyclic voltammetry and chronopotentiometry, respectively. The results demonstrated that the content of GO used during synthesis process affected the specific capacity of nanocomposites while they were constructed as supercapacitor electrode. Compared with pure GO and ZIF-67 nanocubes, ZIF-67/GO-n composites had better specific capacitance. While the concentration of GO was 2 wt% based on their initial total mass of two reactants, ZIF-67/GO-2 composite presents a specific capacitance of 100.41 F g−1 at a sweep rate of 5 mV s−1. The good electrochemical performance of ZIF-67/GO-n composite may be credited to large BET surface area of ZIF-67 nanocubes and good conductivity of GO, and thus is expected to become a potential electrode material for supercapacitors.

We present the self-assembly synthesis of core–shell structure Au/CeO2 composites with different Au loadings through a spontaneous chemical redox approach at an ambient temperature utilizing HAuCl4 and Ce(NO3)3 as reaction substrates in an alkaline environment. The results demonstrate that the as-synthesized Au/CeO2 composites exhibit spherical shape morphologies with porous structures, composed of Au nanoparticle (∼10 nm) cores and CeO2 nanoparticle shells with abundant oxygen vacancies. The introduction of Au nanoparticles in CeO2 not only effectively improves the visible light utilization efficiency but also provides rich surface catalytic active sites for highly efficient visible light photocatalysis. As visible light photocatalysts (λ > 400 nm), the as-synthesized Au/CeO2 composites with the Au loading amount ≥4.0 wt % exhibit high conversion and selectivity (∼100%) of benzyl alcohol to benzaldehyde under the given experimental conditions. Moreover, Au/CeO2 also shows a general applicability as a vis...

Cu2ZnSnS4 (CZTS) is a promising low cost thin-film solar cell material. However, the charge localized defects greatly hinder the improvement of the solar cell efficiency, thus the identification and knowledge of the possible charge localized defects in it are extremely important. Using hybrid functional calculation, we find that Cu Sn and Cu Zn are the main charge localized defects in CZTS. In detail, our results show that Cu Sn is a deep level recombination center. Moreover, the growth condition of Sn determines the population of Cu Sn because the stable chemical potential region of Δ μ Sn ([− 1.74, 0] eV) is larger than that of Δ μ Cu ([− 0.77, 0] eV). Thus Sn-rich growth condition is proposed to suppress the Cu Sn . As for Cu Zn antisites, part is deep acceptors which will be beneficial for the efficiency of solar cell, while part forms donor-acceptor pairs with Zn Cu . The Cu Zn + Zn Cu donor-acceptor pairs will lead to large potential fluctuation in CZTS, which is a disadvantageous factor. Fortunately, such pairs can be greatly suppressed by Cd doping due to two reasons: one is that the Cd atoms prefer to substitute the Zn atomic sites leading to the reduction of the Cu Zn concentration, and the other is that the Cd dopant in the CZTS makes it difficult for its neighboring Zn atom be substituted by Cu atom.

Coexistence of two phases creates a morphotropic phase boundary in perovskite oxides, which can provide large piezoelectric response, generating it a well suited system for probe-based memories and actuator applications. The coexistence of two phases in thin films is proposed to be induced by epitaxial constraints from substrates or chemical compositional modifications by substitution. In this work, we found a new formation mechanism of two-phase coexistence driven by interfacial oxygen octahedral coupling (OOC) in oxide heterostructures. We fabricated a series of BiFeO 3 (BFO) ultrathin films on various orthorhombic substrates exerting from tensile to compressive strains by Pulsed Laser Deposition (PLD) techniques. Aberration-corrected transmission electron microscopy demonstrates that the lattice rotation and oxygen octahedral rotation (OOR) patterns transfer from these substrates to BFO films in about 3 unit cells while an orthorhombic ( Pnma ) phase forms at the interface due to OOC. This Pnma phase is non-polar, which differs from polar phases of Ima2 or Pmc2 1 when a large tensile strain is imposed onto BFO. First-principles calculations reproduce these experimental results perfectly. This phase transition occurs when BFO films are under both tensile and compressive strains suggesting that OOC alone can induce phase transition in ultrathin BFO films. Such coexistence of two phases may have many potential applications in the field of electronics, such as ferroelectric sensors and actuators.

We report a pyrolysis-phosphorization approach to fabricate carbon nanotubes with embedded CoP nanoparticles (CoP/CNs) using ZIF-67 as a precursor for electrocatalytic nitrogen (N2) reduction to ammonia (NH3) under ambient conditions. The results demonstrate that the as-synthesized CoP/CNs as electrocatalysts exhibit high electrocatalytic activity toward the N2 reduction reaction (NRR), affording a large NH3 yield rate of 48.9 μg h-1 mgcat.-1 with a faradaic efficiency (FE) of 8.7% at -0.4 V (vs. RHE) in 0.1 M Na2SO4 electrolyte. The 15N isotopic labelling experiments confirm that the NH3 obtained is indeed from the CoP/CN catalyzed NRR process. Our theoretical calculation results reveal that the N2 molecules prefer to be adsorbed on the highly unsaturated three coordinated Co sites of the CoP(112) plane following an associative distal hydrogenation process.

It is highly attractive but challenging to develop earth-abundant electrocatalysts for nitrogen (N2) fixation. Here, by using density functional theory (DFT), we systematically investigate various single transition metal atom (Ti, V, Cr, Mn, Fe, Co, Ni, Ru, Rh and Pd) modified MoP surfaces as potential N2 reduction electrocatalysts for ammonia (NH3) synthesis. Through comparison of the stabilities of metal atom modified MoP, the adsorption energies and the bond lengths of N2 on different atom modified MoP, we select Mn and V as two candidates and study in detail the possible N2 reduction reaction (NRR) pathways for Mn-MoP and V-MoP. Our results revealed that Mn-MoP and V-MoP exhibit energy change values of 0.95 eV and 0.65 eV, respectively, with the first hydrogenation step being the potential-limiting step. Mn-MoP can efficiently suppress *H adsorption and reduce the competition of the hygrogen evolution reaction (HER) with the NRR; whereas, V-MoP cannot. Therefore, Mn-MoP is a better catalyst to realize the nitrogen reduction reaction. Overall, this work takes one step toward the NRR possibility of transition metal phosphides and provides some important insights and guidance to experiments.

Using hybrid density functional theory, here, we have investigated the electronic, defect and migration properties of Na-related defects in the earth-abundant solar cell absorber material Cu2ZnSnSe4 (CZTSe). We find that among all the Na-related defects, NaZn acts the same way as VCu and CuZn; it is an acceptor and contributes to the p-type conductivity. NaSn is a deep level defect, but it is energetically unfavorable and can be suppressed by the growth conditions. Besides, through migration energy analysis, we prove that Na can easily move in CZTSe through interstitial Na and Cu vacancy mediated mechanisms.

In this study, based on first-principles calculations we report a possible mechanism of efficiency improvement of Sb-doped Cu2ZnSnS4 (CZTS) solar cells from the Sb-related defect point of view. Different from Sb in CuInSe2 which substituted the Cu atomic site and acted as group-13 elements under Cu-poor growth conditions, we find out that Sb prefers to substitute Sn atomic sites and acts as group-14 elements under Cu-poor growth conditions in CZTS. At low Sb concentration, SbSn produces a deep defect level which is detrimental for the solar cell application. At high Sb concentration, Sb 5s states form an isolated half-filled intermediate band at 0.5 eV above the valence band maximum which will increase the photocurrent as well as the solar cell efficiency.

Commercial carbon fiber cloth treated at 450 °C in air (CFC-450) possesses low C[double bond, length as m-dash]O content, exhibiting outstanding oxygen evolution activity in 1.0 M KOH electrolyte with an overpotential of 224 mV at current density of 10 mA cm-2. Meanwhile, we observed an electrochemical corrosion phenomenon associated with the carbon fiber cloth electrocatalyst during the OER tests, especially under high static potentials.

The coupling between antiferrodistortion (AFD) and ferroelectric (FE) polarization, universal for all tilted perovskite multiferroics, is known to strongly correlate with domain wall functionalities in the materials. The intrinsic mechanisms of domain wall phenomena, especially AFD-FE coupling-induced phenomena at the domain walls, have continued to intrigue the scientific and technological communities because of the need to develop the future nano-scale electronic devices. Over the past years, theoretical studies often show controversial results, owing to the fact that they are neither sufficiently nor directly corroborated with experimental evidences. In this work, the AFD-FE coupling at uncharged 180{\deg} and 71{\deg} domain walls in BiFeO3 films are investigated by means of aberration-corrected scanning transmission electron microscopy with high resolution (HR-STEM) and rationalized by phenomenological Landau-Ginsburg-Devonshire (LGD) theory. We reveal a peculiar morphology at the AFD-FE walls, including kinks, meandering, triangle-like regions with opposite oxygen displacements and curvature near the interface. The LGD theory confirms that the tilt gradient energy induces these unusual morphology and the features would change delicately with different kinds of domain walls. Moreover, the 180{\deg} AFD-FE walls are proved to be conductive with an unexpected reduction of Fe-O-Fe bond angle, which is distinct from theoretical predictions. By exploring AFD-FE coupling at domain walls and its induced functionalities, we provide exciting evidences into the links between structural distortions and its electronic properties, which benefit a lot for fundamental understanding for domain wall functionalities as well as functional manipulations for novel nano-devices., Comment: 31 pages, 8 figures, 5 appendices

GaSe is a layered semiconductor with an optical band gap tunable by the number of layers in a thin film. This is promising for application in micro/optoelectronics and photovoltaics. However, for that, knowledge about the intrinsic defects are needed, since they may influence device behavior. Here we present a comprehensive study of intrinsic point defects in both bulk and monolayer (ML) GaSe, using an optimized hybrid functional which reproduces the band gap and is Koopmans' compliant. Formation energies and charge transition levels are calculated, the latter in good agreement with available experimental data. We find that the only intrinsic donor is the interlayer gallium interstitial, which is absent in the case of the ML. The vacancies are acceptors, the selenium interstitial is electrically inactive, and small intrinsic defect complexes have formation energies too high to play a role in the electronic properties of samples grown under quasi-equilibrium conditions. Bulk GaSe is well compensated by the intrinsic defects, and is an ideal substrate. The ML is intrinsically p-type, and p-type doping cannot be compensated either. The opening of the band gap changes the defect physics considerably with respect to the bulk.

The influence of high temperature (over the melting point) annealing on the properties of poly (3-hexylthiophene) (P3HT) films had been investigated. By comparing the films with different annealing temperature, we found that P3HT films annealed at 260 °C is similar to amorphous melting process, although it had the highest crystallinity. The film thickness was increased after annealing at 260 °C which suggested that there were a large number of ‘micro-pores’ in the films. Since the P3HT backbone around the micro-pores was in a nearly free state (easy to rotate and bend), the samples annealed at 260 °C would exhibit a similar ‘melting’ behavior at low temperature (below 180 °C) with the highest crystallinity.

Here, we have systematically investigated the electronic structure and optical properties of transition metal (M) doped CuGaS2 (M = Fe, Co, and Ni) systems, using a density functional theory by considering a non-local interaction. Isolated intermediate bands (IBs), with the potential of achieving the efficiency of photovoltaic materials, are introduced in the main band gap of the host CuGaS2 by doping Fe or Ni with a favorable position and width. Therefore, extra absorption peaks appear in the optical spectrum of the Fe and Ni doped CuGaS2 compounds, accompanied with a greatly enhanced light absorption intensity and a largely broadened light absorption energy range. Whereas for Co doped CuGaS2, the material turns into a half-metal. Consequently, Fe and Ni doped CuGaS2 could be potential materials for future applications in the photovoltaic area.

A cross-linked network is obtained by an end-group cross-linkable PBI (E-PBI) and 4,4′-diglycidyl (3,3′,5,5′-tetramethylbiphenyl) epoxy resin (TMBP). The formation of the network is proved by FT-IR and gel fraction test. Then, high temperature proton exchange membranes are constructed by incorporating the cross-linked network into poly(2,2′-(1,3-phenylene)-5,5′-bibenzimidazole) (m-PBI). The influences of the end-group cross-linked network on the properties of membranes are studied, such as, phosphonate acid doping ability, thermal stability, mechanical property, oxidative stability and proton conductivity. The E-PBI/TMBP in the membranes contributes to the improvement of acid doping ability, proton conductivity, mechanical properties and oxidative stabilities. The blend membranes with 20–90 wt% E-PBI/TMBP show higher proton conductivity than pristine PBI at 120 °C–180 °C. These results indicate that the end-group cross-linked blend membranes are promising materials as high temperature proton exchange membranes.

A series of novel composites based on different ratios of epoxidised cresol novolac (ECN) and 4,4′-diglycidyl(3,3′,5,5′-tetramethylbiphenyl) epoxy resin (TMBP) have been prepared with the curing agent 4,4′-methylenediamine (DDM) and 4,4′-diaminodiphenylsulfone (DDS), respectively. The investigation of cure kinetics was performed by differential scanning calorimetry using an isoconversional method. The high thermal stabilities of the cured samples were also studied by thermogravimetric analysis. In addition, no phase separation was observed for cured ECN/DDM and ECN/DDS blending with different amounts of TMBP by dynamic mechanical analysis and scanning electron microscopy. Moreover, the cured systems also exhibited excellent impact properties and low moisture absorption. All the results indicate that the ECN/TMBP/DDM and ECN/TMBP/DDS systems are promising materials in electronic packaging. Copyright © 2011 Society of Chemical Industry

The Haber‐Bosch process can be replaced by the ambient electrocatalytic N2 reduction reaction (NRR) to produce NH3 if suitable electrocatalysts can be developed. However, to develop high performance N2 fixation electrocatalysts, a key issue to be resolved is to achieve efficient hydrogenation of N2 without interference by the thermodynamically favored hydrogen evolution reaction (HER). Herein, in‐operando created strong Li–S interactions are reported to empower the S‐rich MoS2 nanosheets with superior NRR catalytic activity and HER suppression ability. The Li+ interactions with S‐edge sites of MoS2 can effectively suppress hydrogen evolution reaction by reducing H* adsorption free energy from 0.03 to 0.47 eV, facilitate N2 adsorption by increasing N2 adsorption free energy from –0.32 to –0.70 eV and enhance electrocatalytic N2 reduction activity by decreasing the activation energy barrier of the reaction control step (*N2 → *N2H) from 0.84 to 0.42 eV. A NH3 yield rate of 43.4 μg h−1 mg−1 MoS2 with a faradaic efficiency (FE) of 9.81% can be achieved in presence of strong Li–S interactions, more than 8 and 18 times by the same electrocatalyst in the absence of Li–S interactions. This report opens a new way to design and develop catalysts and catalysis systems.

The objective of this study was to develop a suitable formulation for baicalein (a poorly water-soluble drug exhibiting high melting point) to prepare solid dispersions using hot melt extrusion (HME). Proper carriers and plasticizers were selected by calculating the Hansen solubility parameters, evaluating melting processing condition, and measuring the solubility of obtained melts. The characteristic of solid dispersions prepared by HME was evaluated. The dissolution performance of the extrudates was compared to the pure drug and the physical mixtures. Physicochemical properties of the extrudates were characterized by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and Fourier transform infrared spectroscopy (FTIR). Relative bioavailability after oral administration in beagle dogs was assessed. As a result, Kollidon VA64 and Eudragit EPO were selected as two carriers; Cremophor RH was used as the plasticizer. The dissolution of all the extrudates was significantly improved. DSC and PXRD results suggested that baicalein in the extrudates was amorphous. FTIR spectroscopy revealed the interaction between drug and polymers. After oral administration, the relative bioavailability of solid dispersions with VA64 and EPO was comparative, about 2.4- and 2.9-fold greater compared to the pure drug, respectively.

A series of SPEEK/HPW/Ppy-n composite membranes with a sandwich structure were successfully prepared by surface modification with polypyrrole (Ppy) in order to stabilize phosphotungstic acid (HPW) in poly(ether ether ketone)s (SPEEKs) and reduce the methanol crossover. Ppy coatings with a large number of secondary ammonium groups (NH2+) interact with anions of HPW to decrease HPW leaching from the membrane. In addition, the hydrophobic Ppy layers allow for little methanol transport, which leads to a significant decline in methanol crossover with reasonable levels of proton conductivity. The properties of the membranes were investigated in detail by UV, SEM, ac impedance, and TGA. As observed, Ppy-modified membranes were better at immobilizing HPW and exhibited higher selectivities than previously reported SPEEK/HPW composite membranes. All the results indicate that the SPEEK/HPW/Ppy-n composite membranes are excellent candidates for direct methanol fuel cells.

A carboxyl-terminated benzimidazole trimer was synthesized as a crosslinker by controlling the ratio of 3,3′-diaminobenzidine and isophthalic acid. Composite membranes were obtained by mixing the benzimidazole trimer and sulfonated poly(ether ether ketone) (SPEEK) together. Cross-linked membranes were obtained by heating the composite membranes at 160 °C. All of the properties of the cross-linked membranes were significantly increased, including proton conductivity, methanol permeability and water uptake due to the more compact structure compared to the non-cross-linked membranes. The cross-linked SPEEK-BI7 and cross-linked SPEEK-BI11 had excellent proton conductivities (0.22 and 0.19 S cm−1) at 80 °C, which were higher than that of Nafion 117 (0.125 S cm−1). Transmission electron microscopy (TEM) analysis revealed a clear microphase separated structure of cross-linked membranes. Other properties, such as thermal and mechanical stability, required for use as a proton exchange membrane (PEM) have been investigated. The cross-linked membranes showed improved properties over membranes without crosslinking.

Proton exchange membranes with high dimensional stabilities and low water uptakes were constructed by incorporating phosphotungstic acid (PWA) into a cross-linked network composed of a crosslinkable sulfonated poly(ether ether ketone) containing dipropenyl groups (SDPEEK) and γ-methacryloxypropyltrimethoxysilane (KH570). The chemical structures of the hybrid membranes were confirmed by FT-IR spectroscopy and scanning electron microscopy (SEM). The results indicated that PWA particles were well dispersed in these membranes. The influences of the dispersed PWA on the properties of membranes such as thermal stability, water uptake, swelling ratio, proton conductivity, methanol permeability and mechanical property were researched. The addition of KH570-5/PWA in the hybrid membranes contributed to the improvement of the dimensional stabilities. And the hybrid membranes with 10–40wt% PWA showed higher proton conductivities than Nafion 117 at 80 °C, while the methanol permeabilities of these membranes were much lower than that of Nafion 117. The membranes also exhibited excellent mechanical properties. These results imply that the SDPEEK/KH570-5/PWA-x membranes are promising materials in the direct methanol fuel cells (DMFC) applications.