Dry reforming of methane (DRM) is an attractive route to utilize CO
as a chemical feedstock with which to convert CH
into valuable syngas and simultaneously mitigate both greenhouse gases. Ni-based ...DRM catalysts are promising due to their high activity and low cost, but suffer from poor stability due to coke formation which has hindered their commercialization. Herein, we report that atomically dispersed Ni single atoms, stabilized by interaction with Ce-doped hydroxyapatite, are highly active and coke-resistant catalytic sites for DRM. Experimental and computational studies reveal that isolated Ni atoms are intrinsically coke-resistant due to their unique ability to only activate the first C-H bond in CH
, thus avoiding methane deep decomposition into carbon. This discovery offers new opportunities to develop large-scale DRM processes using earth abundant catalysts.
Ceramic aerogels are attractive for many applications due to their ultralow density, high porosity, and multifunctionality but are limited by the typical trade-off relationship between mechanical ...properties and thermal stability when used in extreme environments. In this work, we design and synthesize ceramic nanofibrous aerogels with three-dimensional (3D) interwoven crimped-nanofibre structures that endow the aerogels with superior mechanical performances and high thermal stability. These ceramic aerogels are synthesized by a direct and facile route, 3D reaction electrospinning. They display robust structural stability with structure-derived mechanical ultra-stretchability up to 100% tensile strain and superior restoring capacity up to 40% tensile strain, 95% bending strain and 60% compressive strain, high thermal stability from -196 to 1400 °C, repeatable stretchability at working temperatures up to 1300 °C, and a low thermal conductivity of 0.0228 W m
K
in air. This work would enable the innovative design of high-performance ceramic aerogels for various applications.
Surface-supported isolated atoms in single-atom catalysts (SACs) are usually stabilized by diverse defects. The fabrication of high-metal-loading and thermally stable SACs remains a formidable ...challenge due to the difficulty of creating high densities of underpinning stable defects. Here we report that isolated Pt atoms can be stabilized through a strong covalent metal-support interaction (CMSI) that is not associated with support defects, yielding a high-loading and thermally stable SAC by trapping either the already deposited Pt atoms or the PtO
units vaporized from nanoparticles during high-temperature calcination. Experimental and computational modeling studies reveal that iron oxide reducibility is crucial to anchor isolated Pt atoms. The resulting high concentrations of single atoms enable specific activities far exceeding those of conventional nanoparticle catalysts. This non defect-stabilization strategy can be extended to non-reducible supports by simply doping with iron oxide, thus paving a new way for constructing high-loading SACs for diverse industrially important catalytic reactions.
Recently, various titanium dioxide (TiO2) nanostructures have received increasing attention in the fields of energy conversion and storage owing to their electrochemical properties. However, these ...particulate nanomaterials exclusively exist in the powder form, which may cause health risks and environmental hazards. Herein we report a novel, highly elastic bulk form of TiO2 for safe use and easy recycling. Specifically, TiO2 nanofibrous aerogels (NAs) consisting of resiliently bonded, flexible TiO2 nanofibers are constructed, which have an ultralow bulk density, ultrahigh porosity, and excellent elasticity. To promote charge transfer, they are subjected to lithium reduction to generate abundant oxygen vacancies, which can modulate the electronic structure of TiO2, resulting in a conductivity up to 38.2 mS cm−1. As a proof‐of‐concept demonstration, the conductive and elastic TiO2 NAs serve as a new type of self‐supported electrocatalyst for ambient nitrogen fixation, achieving an ammonia yield of 4.19×10−10 mol s−1 cm−2 and a Faradaic efficiency of 20.3 %. The origin of the electrocatalytic activity is revealed by DFT calculations.
Conductive and elastic TiO2 nanofibrous aerogels (NAs), with a hierarchically ordered, cellular architecture consisting of resiliently bonded nanofibers, can be prepared. As a proof‐of‐concept demonstration, the TiO2 NAs serve as a new type of self‐supported electrocatalysts with high activity and durability for ambient nitrogen fixation.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
White‐light‐emissive organic micro/nanostructures hold exotic potential applications in full‐color displays, on‐chip wavelength‐division multiplexing, and backlights of portable display devices, but ...are rarely realized in organic core/shell heterostructures. Herein, through regulating the noncovalent interactions between organic semiconductor molecules, a hierarchical self‐assembly approach of horizontal epitaxial‐growth is demonstrated for the fine synthesis of organic core/mono‐shell microwires with multicolor emission (red–green, red–blue, and green–blue) and especially organic core/double‐shell microwires with radial red–green–blue (RGB) emission, whose components are dibenzog,pchrysene (DgpC)‐based charge‐transfer (CT) complexes. In fact, the desired lattice mismatching (≈2%) and the excellent structure compatibility of these CT complexes facilitate the epitaxial‐growth process for the facile synthesis of organic core/shell microwires. With the RGB‐emissive substructures, these core/double‐shell organic microwires are microscale white‐light sources (CIE 0.34, 0.36). Besides, the white‐emissive core/double‐shell microwires demonstrate the fascinating full‐spectrum light transportation from 400 to 700 nm. This work indeed opens up a novel avenue for the accurate construction of organic core/shell heterostructures, which provides an attractive platform for the organic integrated optoelectronics.
Through regulating the noncovalent interactions between organic semiconductor molecules (|ECT, DgpC‐TCNB = −18.35 kcal mol−1| > |ECT, DgpC‐TFP = −13.45 kcal mol−1| > |Eπ–π, DgpC = −6.81 kcal mol−1|), a hierarchical self‐assembly approach of horizontal epitaxial‐growth is demonstrated for the precise synthesis of organic core/double‐shell microwires with radial red–green–blue (RGB) substructures for miniaturized white‐light sources (CIE 0.34, 0.36).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Abstract
Semi-hydrogenation of acetylene in excess ethylene is a key industrial process for ethylene purification. Supported Pd catalysts have attracted most attention due to their superior intrinsic ...activity but often suffer from low selectivity. Pd single-atom catalysts (SACs) are promising to significantly improve the selectivity, but the activity needs to be improved and the feasible preparation of Pd SACs remains a grand challenge. Here, we report a simple strategy to construct Pd
1
/TiO
2
SACs by selectively encapsulating the co-existed small amount of Pd nanoclusters/nanoparticles based on their different strong metal-support interaction (SMSI) occurrence conditions. In addition, photo-thermo catalysis has been applied to this process where a much-improved catalytic activity was obtained. Detailed characterization combined with DFT calculation suggests that photo-induced electrons transferred from TiO
2
to the adjacent Pd atoms facilitate the activation of acetylene. This work offers an opportunity to develop highly stable Pd SACs for efficient catalytic semi-hydrogenation process.
Disulfide bonds play an important role in thiol‐based redox regulation. However, owing to the lack of analytical tools, little is known about how local O2 mediates the reversible thiol/disulfide ...cycle under protein confinement. In this study, a protein‐nanopore inside a glove box is used to control local O2 for single‐molecule reaction, as well as a single‐molecule sensor for real‐time monitoring of the reversible thiol/disulfide cycle. The results demonstrate that the local O2 molecules in protein nanopores could facilitate the redox cycle of disulfide formation and cleavage by promoting a higher fraction of effective reactant collisions owing to nanoconfinement. Further kinetic calculations indicate that the negatively charged residues near reactive sites facilitate proton‐involved oxygen‐induced disulfide cleavage under protein confinement. The unexpectedly strong oxidation ability of confined local O2 may play an essential role in cellular redox signaling and enzyme reactions.
The reversible thiol/disulfide cycle under protein confinement was monitored in real‐time using a mutant aerolysin nanopore. Experiments combined with kinetic calculations revealed that confined local O2 can lead to proton‐involved, oxygen‐induced disulfide bond cleavage. The negatively charged neighboring microenvironment facilitates disulfide bond cleavage, which plays a vital role in redox signaling and reactions.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
A bio‐inspired design of using metal–organic framework (MOF) microcrystals with well‐defined multi‐shelled hollow structures was used as a matrix to host multiple guests including molecules and ...nanoparticles at separated locations to form a hierarchical material, mimicking biological structures. The interactions such as energy transfer (ET) between different guests are regulated by precisely fixing them in the MOF shells or encapsulating them in the cavities between the MOF shells. The proof‐of‐concept design is demonstrated by hosting chromophore molecules including rhodamine 6G (R6G) and 7‐amino‐4‐(trifluoromethyl)coumarin (C‐151), as well as metal nanoparticles (Pd NPs) into the multi‐shelled hollow zeolitic imidazolate framework‐8 (ZIF‐8). We could selectively establish or diminish the guest‐to‐framework and guest‐to‐guest ET. This work provides a platform to construct complex multifunctional materials, especially those need precise separation control of multi‐components.
The right home for ET: Metal–organic framework (MOF) microcrystals with a multi‐shelled hollow structure serve as an ideal matrix to precisely host multiple guest molecules (see picture; R6G and C‐151 dyes) and nanoparticles at separated locations. The energy transfer (ET) of guest‐to‐frame and guest‐to‐guest could be switched by controlling their locations.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Single nanoparticle (NP) electrochemical measurements are widely described, both theoretically and experimentally, as they enable visualization of the electrochemical signal of a single NP that is ...masked in ensemble measurements. However, investigating the behavior of individual NPs using electrochemical signals remains a significant challenge. Here we report experiments and simulations demonstrating that multiple distinct motion trajectories could be discerned from time-resolved current traces by dynamic Monte Carlo simulations. We show that continuous monitoring and quantification of electrochemical oxidation of individual AgNPs using a low-noise electrochemical measurement platform produce significantly distinguished current traces due to the size-dependent motions of AgNPs. Our findings offer a view of the electrochemical signals of individual NPs that are largely different from that in the literature, and underscore the significance of motion behaviors in single NP electrochemistry.
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IJS, KILJ, NUK, UL, UM, UPUK
The synthesis of bio-based linear diols is the subject of many research studies. However, one of the main obstacles in industrial development is the difficulty in controlling product selectivity. ...Here, we report the catalytic conversion of furfural to 1,4-pentanediol (PD) in the presence of Ru supported on an ordered mesoporous carbon (CMK-3) under pressure of H 2 and CO 2 in water. In contrast to previous catalytic pathways, this work is distinct in that it yields 1,4-PD as an exclusive product, instead of a mixture of 1,2- and 1,5-PD as usual. Under optimized conditions, 1,4-PD was obtained in 90% yield, and in a one-pot reaction, directly from furfural. We disclose that the conversion of furfural to 1,4-PD followed an unusual catalytic route. It implies a bifunctional catalytic pathway based on sequential catalytic hydrogenation reactions and an acid-catalyzed Piancatelli's rearrangement.
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