查看更多>>摘要：To clarify the performance differences between Cs-O and Cs-NF3-activated GaAs photocathodes, the changes in adsorption characteristics with Cs coverage for the Cs-O and Cs-NF3-adsorbed GaAs(100)-beta(2)( 2 x 4) surfaces were investigated by first-principles calculation based on density function theory. The simulation results show that under the same Cs coverage, the Cs-NF3-adsorbed GaAs surface is more stable than the Cs-only and Cs-O-adsorbed surfaces. In the case of small Cs coverage, the Cs-O-adsorbed GaAs surface exhibits a lower work function than Cs-NF3 does. When the Cs coverage reaches one monolayer, however, the Cs-NF3 adsorption model possesses a stronger dipole moment resulting in an even lower work function. According to theoretical prediction guidance, the Cs-O and Cs-NF3 activation experiments adopting the excessive Cs deposition recipe were performed for preparing GaAs photocathodes. The experimental results show that the Cs-NF3-activated GaAs photocathode has a higher quantum efficiency in the whole waveband and better emission stability under white light illumination than the Cs-O-activated photocathode, which agrees with the differences in work function and adsorption energy between the two adsorption model types. It is concluded that the Cs-NF3 activation recipe using excessive Cs supply is preferred to enhance photoemission performance of GaAs photocathode. (C) 2022 Elsevier Inc. All rights reserved.
Lu, RunqingSam, Daniel KobinaWang, WenboGong, Shanhe...
10页
查看更多>>摘要：The electrocatalytic performance of oxygen evolution reaction (OER) electrocatalysts is highly reliant on the activity of its catalytic active site, which may be augmented by raising the number of active sites. In this study, nanoscaled nickel-cobalt-iron (NiCoFe) alloy was embedded on conductive boron(B), nitrogen (N) co-doped/biomass-derived carbon aerogel as an OER electrocatalyst. The synthesized electrocatalysts were calcined under different temperatures and with variable dopants. The optimal electrocatalyst (BN/ CA-NiCoFe-600) demonstrated a low overpotential of 321 mV (at current density of 10 mA cm-2) and a minute Tafel slope of 42 mV dec-1, which was even smaller than that of IrO2 and RuO2. Its mass activity and specific activity were calculated to be 201.7 A g-1, and 34.1 cm-2 ECSA, respectively. Furthermore, the electrocatalyst showed excellent stability and durability. This work provides an easy and practical synthetic strategy for acquiring very active and durable electrocatalysts for OER. (c) 2022 Elsevier Inc. All rights reserved.
查看更多>>摘要：A multifunctional graphitic carbon nitride (GCN) protective layer with bionic ion channels and high stability is prepared to inhibit dendrite growth and side reactions on zinc (Zn) metal anodes. The high electronegativity of the nitrogen-containing organic groups (NOGs) in the GCN layer can effectively promote the dissociation of solvated Zn2+ and its rapid transportation in bionic ion channels via a hopping mechanism. In addition, this GCN layer exhibits excellent mechanical strength to suppress the growth of Zn dendrites and the volume expansion of Zn metal anodes during the plating process. Consequently, the electrodeposited Zn presents a uniform and densely packed morphology with negligible side-product accumulation. As a result, the half-cell composed of the Cu-GCN anode can deliver a remarkable longterm cycling performance of 1000 h at 0.5 mA cm(-2) and 0.25 mAh cm(-2). A full cell assembled with MnO2 cathode also displays improved long-term cycling performance (150 cycles at 200 mA g(-1)) when the Cu-GCN@Zn composite anode is applied. This work deepens our understanding of the kinetics of ion migration in the interface layer and paves the way for next-generation high energy-density Zn-metal batteries (ZMBs). (C) 2022 Elsevier Inc. All rights reserved.
查看更多>>摘要：Hypothesis: Although a lot of fluorinated coatings exhibit super-repellency to oils with low surface ten-sions, most of them are readily wetted by alcohols with high surface tensions, wherein the un-crosslinked fluorinated silane is expected to result in the failure of alcohol-repellency. Hence, the coating could be super-repellent to alcohols if the fluorinated silane is fully crosslinked by annealing. Experiments: We fabricate the super-alcohol-repellent coating via covering sintered hollow silica nano-spheres with perfluoroalkyl silane, followed by a simple two-step annealing. The surface chemistry of the coating is further examined by X-ray photoelectron spectroscopy. Findings: The super-alcohol-repellent coating is remarkably super-repellent to diverse alcohols of surface tension from 20.9 to 64.8 mN m(-1) and thus enables loss-free manipulation of alcohol droplets for amino acid detection. More importantly, we reveal that the annealing procedure could promote the condensa-tion of silanol groups, showing the key role played by heat-mediated crosslinking of perfluoroalkyl silane in preparing alcohol-repellent coatings. Such annealing strategy is also proved to be effective for other fluorinated coatings to achieve super alcohol-repellency. Together with its super-repellency to virtually all liquids, the coating enables loss-free processing of diverse liquids, thus being of significant value for biological, chemical and medical applications. (C) 2022 Elsevier Inc. All rights reserved.
查看更多>>摘要：A series of 3D@2D constructed Al2O3@CoMn2O4 microspheres with a hollow hierarchical structure supporting Pd nanoparticles was successfully synthesized by the the vertical in situ growth of 2D CMO spinel nanosheets on hollow Al2O3 support. The introduction of core-shell hollow hierarchical structure leads to excellent catalytic activity for three kinds of VOCs, high stability and water-resistance and low-cost, making it a multifunctional and promising catalyst for VOC combustion. Catalytic oxidation is a promising method for removing harmful volatile organic compounds (VOCs). Therefore, exploring high-efficiency catalysts for catalyzing VOCs is of great significance to the realization of an environment-friendly and sustainable society. Here, a series of 3D@2D constructed Al2O3@CoMn2O4 microspheres with a hollow hierarchical structure supporting Pd nanoparticles was successfully synthe- sized. The introduction of hollow Al2O3 for the in situ vertical growth of 2D CMO spinel materials con- structs a well-defined core-shell hollow hierarchical structure, leading to larger specific surface area, more accessible active sites and promoted catalytic activity of support material. Additionally, theoretical calculations also indicate that the addition of Al2O3 as the support material strengthens the adsorption of toluene and oxygen on CoMn2O4, which promotes their activation. The dispersion of Pd further strength-ens the low-temperature reducibility along with more active surface oxygen species and lower apparent activation energy. The optimum 1 wt% Pd/h-Al@4CMO catalyst possesses the lowest apparent activation energy for toluene of 77.4 kJ mol(-1), showing the relatively best catalytic activity for VOC oxidation, reaching 100% toluene, benzene, and ethyl acetate conversion at 165, 160, and 155 degrees C, respectively. Meanwhile, the 1 wt% Pd/h-Al@4CMO sample possesses excellent catalytic stability, outstanding selectivity, and good moisture tolerance, which is an effective candidate for eliminating VOCs contaminants. (C) 2022 Published by Elsevier Inc.
查看更多>>摘要：While metal oxides are conventionally proposed for activating monopersulfate (MPS) to degrade refractory contaminants, metal sulfides have recently gained increased attention for MPS activation because these sulfides exhibit more reactive redox characteristics to enhance the catalytic activation of MPS. The present study attempts to develop a novel material comprised of metal sulfides with 3D hierarchical nanostructures to activate MPS. Specifically, a 3D hierarchically structured catalyst was fabricated by growing CuCo-layered double hydroxide (LDH) on nickel foam (NF), followed by direct sulfurization, affording Cu/CoS@NF (CCSNF). CCSNF could exhibit a unique morphology of floral bunches comprised of nano-needles, residing on the NF surfaces. Compared with its precursor, CuCo-LDH@NF, oxide analogue, and CuCo2O4@NF, CCSNF possessed superior physical and chemical properties, including larger surface area and pore volume, higher current density, and lower charge transfer resistance. These features render CCSNF a much more effective catalyst than CuCo-LDH@NF and CuCo2O4@NF for activating MPS to degrade Rhodamine B (RB). In particular, RB degradation by CCSNF-activated MPS required an activation energy only 26.8 kJ/mol, which is much lower than the reported values. The activation mechanism and degradation pathway of RB degradation by CCSNF-activated MPS were investigated and validated through experimental evidences and density function theory calculations. (c) 2021 Published by Elsevier Inc.
查看更多>>摘要：Metal-organic-frameworks (MOFs) derived carbon or nitrogen-doped carbon (NC) materials are usually used as electromagnetic wave (EMW) absorbers. However, the effective control of the composition and structure of composites is still a major challenge for the development of high-performance EMW absorbing materials. In this work, core-shell structure and bimetallic composition Cu/nitrogen doped carbon @Co/nitrogen doped carbon (Cu/NC@Co/NC) composites were designed and synthesized through the thermal decomposition of Cu-MOF@Co-MOF precursor. Cu/NC@Co/NC composites with different compositions were obtained by changing the ratio of Co-MOF and Cu-MOF. The composite (Cu/NC@Co/NC-3.75) prepared using 3.75 mmol of Co(NO3)(2)center dot 6H(2)O exhibits outstanding EMW absorption properties due to the optimized impedance matching and strong attenuation ability, which is caused by enhanced interfacial and dipolar polarization as well as multiple reflection and scattering. With the filler loading in paraffin of 35 wt%, the minimum reflection loss (RLmin) is up to-54.13 dB at 9.84 GHz with a thin thickness of 3 mm, and the effective absorption bandwidth (EAB, RL <= -10 dB) reaches 5.19 GHz (10.18- 15.37 GHz) with the corresponding thickness of 2.5 mm. Compared with the Cu/NC and Co/NC, the Cu/NC@Co/NC-3.75 composite exhibits much better EMW absorbing performances caused by the bimetallic composition and the unique core-shell structure. This work provides a rational design for MOF-derived lightweight and broadband EMW absorbing materials. (C) 2021 Elsevier Inc. All rights reserved.
查看更多>>摘要：The design and development of efficient and durable catalysts with visible-light response for photocatalytic hydrogen production and pollutants degradation is considered as one of the most challenging tasks. In present work, a novel Cu2WS4/NiTiO3 (abbreviated as CWS/NTO; x = 0.25, 0.50, 0.75 and 1.00) composite was prepared via a facile electrospinning/calcination technique along with a convenient hydrothermal method. The as-prepared CWS/NTO composite was composed of 2D CWS nanosheets and 1D NTO nanofibers manifested by SEM and TEM images. The results of XPS verified the interfacial interaction between CWS and NTO, confirming the heterojunction formation in CWS/NTO composite. Photocatalytic tests demonstrated as-prepared CWS/NTO catalysts exhibited outstanding and stable photocatalytic performances for H-2 production and pollutants degradation under visible light (lambda > 420 nm) irradiation. Specially, 0.50 CWS/NTO sample displayed the highest H-2-evolution activity of 810 lmol.g(-1)-h(-1) with the apparent quantum efficiency (AQE) value of 1.65 % at 420 nm. Additionally, it also exhibited the optimal photodegradation properties with the rate constants of 0.030, 0.413 and 0.028 min(-1) for TC, RhB and Cr(VI), respectively. The excellent catalytic activities could be attributed to the enhanced visible light adsorption, high specific surface area and efficient separation of photogenerated charge carriers. The ESR tests and free radicals capturing experiments confirmed that.O-2(-) and h(+) were primary active species for TC/RhB degradation. Eventually, the probable catalytic mechanism was put forward and detailly analysed. The present work provides perspectives of rational design on NiTiO3-based catalysts with superior photocatalytic performance for energy regeneration and environmental remediation. (C) 2022 Published by Elsevier Inc.
Lin, MaoqiRaghuwanshi, Vikram SinghBrowne, ChristineSimon, George P....
11页
查看更多>>摘要：Hypothesis: The conditions to allow self-assembly of cellulose nanocrystal (CNC) suspensions into chiral nematic structures are based on aspect ratio, surface charge density and a balance between repulsive and attractive forces between CNC particles. Experiments: Three types of systems were characterized in suspensions and subsequently in their solid dried films: 1) neat water dialyzed CNC, 2) CNC combined with polyethylene glycol(PEG) (CNC/PEG), and 3) CNC with added salt (CNC/Salt). All suspensions were characterized by polarized optical microscope (POM) and small angle X-ray scattering (SAXS), while the resultant dried films were analyzed by reflectance spectrometer, scanning electron microscope (SEM) and SAXS. Findings: The presence of chiral nematic (CN*) structures was not observed in dialyzed aqueous suspensions of CNC during water evaporation. By introducing salts or a non-adsorbing polymer, chirality was apparent in both suspensions and films. The interaxial angle between CNC rods increased when the suspensions of CNC/PEG and CNC/salt were dried to solid films. The angle was found to be dependent on both species of ions and ionic strength, while the inter-particle distance was only related to the salt concentration, as explained in terms of interaction energies. The CNC suspensions/film chirality can be modulated by controlling the colloidal forces. (c) 2022 Elsevier Inc. All rights reserved.
Whittaker, Michael R.Boyd, Ben J.Quinn, John F.Urquhart, Matthew C....
6页
查看更多>>摘要：Hydrogen sulfide (H2S) is an important signalling molecule with potential pharmaceutical applications. In pursuit of a suitable delivery system for H2S, herein we apply an amphiphilic trisulfide to concomitantly alter the mesophase behaviour of dispersed lipid particles and enable triggered H2S release. Amperometric release studies indicate the trisulfide acts as a sustained H2S donor, with inclusion into the mesophase attenuating release vs neat dispersed trisulfide. Taken together the results highlight the potential for including trisulfide-based additives in stimuli-responsive drug delivery vehicles. (C) 2022 Elsevier Inc. All rights reserved.
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