Ramirez-Vidal, PamelaSuarez-Garcia, FabianCanevesi, Rafael L. S.Castro-Muniz, Alberto...
15页
查看更多>>摘要：Hyper-crosslinked polymers (HCPs) have been produced by the Friedel-Crafts reaction using anthracene, benzene, carbazole or dibenzothiophene as precursors and dimethoxymethane as crosslinker, and the effect of graphene oxide (GO) addition has been studied. The resulting HCPs were highly microporous with BET areas (ABET) between 590 and 1120 m(2) g(-1). The benzene-derived HCP (B1FeM2) and the corresponding composite with GO (B1FM2-GO) exhibited the highest ABET and were selected to study their hydrogen adsorption capacities in the pressure range of 0.1 - 14 MPa at 77 K. The maximum H-2 excess uptake was 2.1 and 2.0 wt% for B1FeM2 and B1FeM2-GO, respectively, at 4 MPa and 77 K. The addition of GO reduced the specific surface area but increased the density of the resultant HCP-GO composites, which is beneficial for practical applications and proves that materials giving higher gravimetric storage capacities are not necessarily those that offer higher volumetric capacities. H-2 adsorption-desorption cycles up to 14 MPa showed irreversible deformation of both HCP and HCP-GO materials, which calls into question their application for hydrogen adsorption at pressures above 4 MPa. (C) 2021 The Authors. Published by Elsevier Inc.
查看更多>>摘要：The rational design and preparation of advanced electrocatalysts for the hydrogen evolution reaction (HER) under alkaline conditions is the key to achieving sustainable hydrogen production. Herein, a new type of nitrogen-doped porous carbon nanosheets (NPCN) loaded with platinum group metals (Pd, Pt or Ru) were prepared. The introduction of melamine not only realized the doping of N-species, but also optimized the morphology and surface functional groups of the prepared catalysts. The prepared Pd-NPCN, Pt-NPCN and Ru-NPCN with a metal loading of about 10 wt% showed outstanding HER activity (21, 9 and 11 mv at 10 mA cm(-2) current density), small Tafel slopes (49, 30 and 30 mV dec(-1)) and good stability in 1.0 M KOH. In addition, the mechanism of the introduction of melamine to improve the catalytic performance of HER was also discussed. Therefore, this work provides promising alternatives to traditional Pt-based catalysts, and is instructive for the design of high-efficiency alkaline HER catalysts. (C) 2021 Elsevier Inc. All rights reserved.
查看更多>>摘要：Herein, a comparative investigation of the Ru-based catalysts with different kinds of supports (TiO2, Al2O3, HZSM-5 SiO2/Al2O3 = 27 and 130, respectively) for catalytic combustion of dichloromethane (DCM) has been performed. The characterization results showed that the C-Cl bond of DCM was cleaved on both the Bronsted and Lewis acid sites of the catalysts. However, the Lewis acid sites were more active than the Bronsted acid sites. The relatively strong Lewis acidity of Ru/TiO2 improved the dissociative adsorption of DCM, accounting for its superior activity. The yield of toxic by-products was strongly associated with the acid types of the catalysts. The Cl species deposited on TiO2 and Al2O3 supports interacted strongly with the Lewis acid sites, thereby promoting the electrophilic chlorination reactions and yielding more polychlorinated by-products, especially highly toxic dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). However, the Cl deposits on Ru/HZSM-5 (SiO2/Al2O3 = 27) with abundant Bronsted acid sites, mainly existed as hydrogen-bonded Cl species, with good mobility and less propensity for chlorinating carbonaceous matter. Moreover, Ru/HZSM-5 (SiO2/Al2O3 = 130) yielded the highest polychlorinated by-products and PCDD/Fs because of its poor redox ability and high surface area. Overall, this study provides valuable insights into the CVOCs catalytic combustion catalysts development. (C) 2021 Elsevier Inc. All rights reserved.
查看更多>>摘要：A quasi-solid-state Li-Te battery is developed by using a flexible gel polymer electrolyte (GPE), porous carbon/tellurium cathode, and lithium metal anode. The ionic conductivity of GPE is controllable and reaches up to 8.0 x 10(-4) S cm(-1) at 25 degrees C. The good interfacial contact with Li metal ensures excellent cycling stability in Li/GPE/Li symmetric cells. Moreover, it is found that, compared to S and Se counterparts, the Li-Te battery exhibits good rate capability due to the high electrical conductivity of Te and excellent interfacial stability among GPE, Li, and Te. This work provides several facile strategies to develop safe and high-performance solid-state Li-Te batteries. (C) 2021 Elsevier Inc. All rights reserved.
Kuldinow, DerekPrzybylak, AlexisLi, YizhiPerez-Lorenzo, Luis J....
15页
查看更多>>摘要：Hypothesis: While the lack of efficient tools yielding controllable uniform saturation ratios (S) has delayed basic experimental heterogeneous nucleation studies, common diffusive condensation particle counters (DCPCs) could fill this gap if their S-variation were minimized by increasing the proportion of sheath gas (sigma) surrounding a central core of purified clusters. Analysis: We measure the activation probability P of Tetraheptylammonium Bromide cluster cations (THA-Br)(n-1)THA(+) in Kanomax's fast CPC while controlling S through the saturator and condenser temperatures (T-s, T-c), varying sigma, and changing the size (n) of purified salt clusters via high resolution mobility selection. Findings: Experimental curves P(T(s,)n) obtained in 1-butanol/air at fixed T-c (13 degrees C) and variable n and T-s (3 < n < 16; 30 < T-s < 40 degrees C) rise sharply versus both n and T-s. Their steepness increases five-fold with increasing sigma to about sigma = 75%, with little effect thereafter. Measurements changing S would yield size distributions of unknown aerosols at fairly high resolution. Comparing P(T(s,)n) data with predictions from capillary theory suggests that basic heterogeneous nucleation measurements can be carried out, but instrument improvements are still needed. (C) 2021 Published by Elsevier Inc.
查看更多>>摘要：Considering versatile potential applications of bioinspired membranes, we simulate the electrokinetic behavior of a cylindrical nanopore, surface modified by a polyelectrolyte (PE) layer. Taking account of the effect of electroosmotic flow and an additionally applied pH gradient, the influences of the strength of the pH gradient, the PE layer thickness, the length of the nanopore and its radius on its conductance and ion current rectification (ICR) performance are assessed. We show that if pHU (the pH at the higher pH end of the nanopore) is fixed at 11 and pHL (the pH at the lower pH end of the nanopore) varies from 3 to 11, the rectification factor Rf has a local maximum occurring in 6 < pH(L) <8; the greater the magnitude of the applied potential bias vertical bar V vertical bar the smaller the pH(L) at which the local maximum occurs. The influence of the PE layer thickness on the nanopore rectification performance is important only if 5 < pH(L) <8, and the optimum performance is reached at a medium thick PE layer (ca. 3 nm). Possible mechanisms associated with the ion transport phenomenon under consideration are proposed and discussed in detail. (C) 2021 Elsevier Inc. All rights reserved.
查看更多>>摘要：Diabetes is a metabolic disease that is affecting an ever-increasing number of people worldwide, resulting in increased burdens on healthcare systems and societies. Constant monitoring of blood glucose levels is required to prevent serious or even deadly complications. One major challenge of diabetes management is the simple and timely administration of insulin to facilitate consistent blood glucose regulation and reduce the incidence of hypoglycemia. With this research, we construct an insulin delivery system, the delivery system is comprised of phenylboronic acid based fluorescent probes, which is used as glucose responsive linkers, mesoporous silica nanoparticles providing an insulin reservoir, and zinc oxide nanoparticles used as gate keepers. The system with glucose sensitive responsive linker exhibits controlled release of insulin under high glucose concentrations, providing prolonged blood glucose regulation and no risks of hypoglycemia. Furthermore, the system is combined with a hyaluronic-acid based microneedle patch, which exhibit efficient skin penetration for transdermal delivery. With our sys-tem, the nanoparticles provide outstanding in vivo glucose regulation when administrated by subcuta-neous injection or via transdermal microneedle patch. We anticipate that our biocompatible smart glucose responsive microneedle patch (SGRM patch) will facilitate the development of clinically useful systems. CO 2021 Elsevier Inc. All rights reserved.
查看更多>>摘要：Ellipsoidal shapes of drops can significantly modify the impact dynamics and suppress the rebound by inducing symmetry breaking in the mass and momentum distributions compared to the axisymmetric dynamics of typical drops. However, the previous works have assumed that the drop oscillation at the moment of impact only slightly affects the post-dynamics although the oscillation must be involved in the spreading. Here, we study the impact dynamics of the oscillating ellipsoidal drops on non-wetting surfaces as a function of the ellipticity, oscillation phase, and Weber number (We) experimentally and numerically. The spreading dynamics show notable hysteretic features in the maximal spreading diameters at the four regions of the oscillation phase. The hysteresis appears more prominently in prolate drops than in oblate drops and becomes remarkably suppressed at the four phases as We increases. Momentum analysis shows that the phases for shaping the drops spherically can drive higher asymmetry in the horizontal momenta than the other phases for shaping the drops ellipsoidally. The momentum asymmetry in the horizontal axes indicates that the oscillation phase as well as the ellipticity can play an important role in altering the hydrodynamics and reducing the bounce magnitude. (c) 2021 Elsevier Inc. All rights reserved.
查看更多>>摘要：Hexavalent chromium (Cr(VI)) is considered to be a potential metal contaminant because of its toxicity and carcinogenicity. In this work, the surface charge density of nickel-iron layered double hydroxide (NiFe LDH) is tuned through iron valence change to improve the performance in adsorption of Cr(VI). The addition of iron divalent in the precursor enhances the surface positivity and reducibility of Fe2+-NiFe LDH, resulting in a nearly 150% Cr(VI) maximum adsorption capacity improvement. The increase of hydroxyl groups and charge density on the surface of NiFe LDH is due to the topological chemical tran-sition from Ni2+-Fe2+ LDH to Ni2+-Fe3+ LDH. The adsorption of Cr(VI) onto Fe2+-NiFe LDH prepared via topochemical approach is highly pH-dependent. The adsorption dynamics and isotherms results may be clearly elucidated by the pseudo-second-order model and Langmuir isotherm model. Electrostatic attraction, interlayer anion exchange and adsorption-coupled reduction are proven to be the main Cr (VI) removal mechanisms for Fe2+-NiFe LDH. This finding demonstrates that Fe2+-NiFe LDH adsorbents have potential application for efficient removal of Cr(VI) pollutants. (C) 2021 Elsevier Inc. All rights reserved.
查看更多>>摘要：Herein, a simple, highly efficient and stable MoS2 nanobox embedded graphitic-C3N4@TiO2 (g-CN@TiO2) nanoarchitecture was synthesized by a facile solvothermal approach. The nano-hybrid photocatalyst was constructed by TiO2 nanoparticles anchored on the surface of g-CN nanosheets. Then highly crystalline three-dimensional porous MoS2 nanobox was homogeneously distributed on the g-CN@TiO2 surface. The g-CN@TiO2/MoS2 hybrid achieved a high photocatalytic degradation efficiency of 97.5% for methylene blue (MB) dye pollutant under visible-light irradiant in an hour which was much better than TiO2@MoS2, g-CN@TiO2, MoS2, TiO2 and g-CN. Furthermore, the reaction rate (k) value of g-CN@TiO2/MoS2 for MB dye is as high as 3.18 X 10(-2) min(-1), which is similar to 2.65 times better than those of g-CN@TiO2 and MoS2. This work presents a rational structure design, interfacial construction and suitable band gap strategy to synthesize advanced nano-hybrid photocatalyst for degradation of organic pollutant with excellent performance and long-term stability. (C) 2021 Elsevier Inc. All rights reserved.
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