A small amount of Co (0.5 wt%) supported on dealuminated Beta zeolite shows much better catalytic performance than other Co catalysts. The small confined metallic Co serving as the active site is ...proposed.
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•CoSiBeta catalysts have state-of-the-art productivity for direct dehydrogenation of propane.•CoSiBeta catalysts with or without prereduction show similar catalytic performance.•The CoOx species confined in the silanols of SiBeta can be reduced to small metallic Co particles.•The confined small metallic Co particles are catalytically active for PDH.
CoOx within dealuminated Beta (SiBeta) zeolite developing into ultrasmall-sized Co particles under H2 or reactant gas is highly efficient for catalyzing direct dehydrogenation of propane (PDH) to propylene reaction. The existence of highly dispersed CoOx species is identified, and the easily reducible CoOx species are confined in the created T-sites (silanols) of SiBeta support. The CoSiBeta catalysts with or without prereduction treatments show similar catalytic performance but different induction periods, implying that the metallic Co formed in situ during the reaction are the active sites. Co in SiBeta zeolite (0.5 wt%) showed state-of-the-art propylene productivity with propane conversion of about 72% and propylene selectivity of over 92% at 600 °C, which is far better than that of the other reported Co catalysts and comparable to that of industrial catalysts. This work proves the high catalytic ability and product selectivity of small confined Co particles, as well as providing novel inspiration for the design of low-cost, ecofriendly, and advanced catalysts for PDH.
Ordered mesoporous carbon materials have recently aroused great research interest because of their widespread applications in many areas such as adsorbents, catalysts and supports, gas storage hosts, ...and electrode materials. The direct synthesis strategy from organic-organic self-assembly involving the combination of polymerizable precursors and block copolymer templates is expected to be more flexible in preparing mesoporous carbons, compared with the traditional nanocasting strategy of complicated and high-cost procedures using mesoporous silica materials as the hard template. In this review, we present the fundamentals and recent advances related to the field of ordered mesoporous carbon materials from the direct synthesis strategy of block copolymer soft-templating, with a focus on their controllable preparation, modification and potential applications. Under the guidance of their formation mechanism, the preparation of ordered mesoporous carbons are discussed in detail by consulting different experimental conditions, including synthetic pathways, precursors, catalysts and templates. Both the mesopore size and morphology control are introduced. The potential applications of pure mesoporous carbons, nonmetallic- and metallic-modified mesoporous carbons, and some interpenetrating carbon-based composites are demonstrated. Furthermore, remarks on the challenges and perspectives of research directions are proposed for further development of the ordered mesoporous carbons (232 references).
, which is one of the largest genera of Gentianoideae, most of which had potential pharmaceutical value, and applied to local traditional medical treatment. Because of the phytochemical diversity and ...difference of bioactive compounds among species, which makes it crucial to accurately identify authentic
species. In this paper, the feasibility of using the infrared spectroscopy technique combined with chemometrics analysis to identify
and its related species was studied. A total of 180 batches of raw spectral fingerprints were obtained from 18 species of
and
by near-infrared (NIR: 10,000-4000 cm
) and Fourier transform mid-infrared (MIR: 4000-600 cm
) spectrum. Firstly, principal component analysis (PCA) was utilized to explore the natural grouping of the 180 samples. Secondly, random forests (RF), support vector machine (SVM), and K-nearest neighbors (KNN) models were built while using full spectra (including 1487 NIR variables and 1214 FT-MIR variables, respectively). The MIR-SVM model had a higher classification accuracy rate than the other models that were based on the results of the calibration sets and prediction sets. The five feature selection strategies, VIP (variable importance in the projection), Boruta, GARF (genetic algorithm combined with random forest), GASVM (genetic algorithm combined with support vector machine), and Venn diagram calculation, were used to reduce the dimensions of the data variable in order to further reduce numbers of variables for modeling. Finally, 101 NIR and 73 FT-MIR bands were selected as the feature variables, respectively. Thirdly, stacking models were built based on the optimal spectral dataset. Most of the stacking models performed better than the full spectra-based models. RF and SVM (as base learners), combined with the SVM meta-classifier, was the optimal stacked generalization strategy. For the SG-Ven-MIR-SVM model, the accuracy (ACC) of the calibration set and validation set were both 100%. Sensitivity (SE), specificity (SP), efficiency (EFF), Matthews correlation coefficient (MCC), and Cohen's kappa coefficient (K) were all 1, which showed that the model had the optimal authenticity identification performance. Those parameters indicated that stacked generalization combined with feature selection is probably an important technique for improving the classification model predictive accuracy and avoid overfitting. The study result can provide a valuable reference for the safety and effectiveness of the clinical application of medicinal
.
This review gives the insights into the various strategies of surface/interface engineering of high-efficiency noble metal-free electrocatalysts for energy-related electrochemical reactions.
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To date, much efforts have been devoted to the high-efficiency noble metal-free electrocatalysts for hydrogen- and oxygen-involving energy conversion reactions, due to their abundance, low cost and multifunctionally. Surface/interface engineering is found to be effective in achieving novel physicochemical properties and synergistic effects in nanomaterials for electrocatalysis. Among various engineering strategies, heteroatom-doping has been regarded as a most promising method to improve the electrocatalytic performance via the regulation of electronic structure of catalysts, and numerous works were reported on the synthesis method and mechanism investigation of heteroatom-doping electrocatalysts, though the heteroatom-doping can only provide limited active sites. Engineering of other defects such as vacancies and edge sites and construction of heterostructure have shown to open up a potential avenue for the development of noble metal-free electrocatalysts. In addition, surface functionalization can attach various molecules onto the surface of materials to easily modify their physical or chemical properties, being as a promising complement or substitute for offering materials with catalytic properties. This paper gives the insights into the diverse strategies of surface/interface engineering of the high-efficiency noble metal-free electrocatalysts for energy-related electrochemical reactions. The significant advances are summarized. The unique advantages and mechanisms for specific applications are highlighted. The current challenges and outlook of this growing field are also discussed.
Developing an efficient and low-cost synthetic approach to controllably synthesize non-precious-metal counter electrode (CE) electrocatalysts with superior catalytic activity and electrochemical ...stability is critically important for the mass production of dye-sensitized solar cells (DSSCs). Herein, we proposed a simple, economical, and easily scalable synthetic route for copyrolysis of melamine and nickel acetate precursors to access the well-defined Ni-encapsulated and nitrogen-doped carbon nanotubes (Ni-NCNTs). The synthetic mechanism was comprehensively investigated by creatively analyzing the phase structure evolution and dynamical decomposition behaviors, and revealed the construction of Ni-NCNTs based on the Ni-catalyzed tip-growth mechanism. Furthermore, the meticulous structural design of Ni nanoparticles intercalated in N-doped CNTs endows Ni-NCNTs with homogeneously distributed Ni–C interfaces, abundant structural defects, and a porous architecture, as well as good electrical conductivity and corrosion-resistance properties. When used as counter electrode for DSSCs, the device delivers a high power conversion efficiency of 8.94% under simulated sunlight (AM 1.5, 100 mW cm–2) and long-term stability with a remnant efficiency of 8.34% after 100 h of illumination, superior to those of conventional Pt. The outstanding catalytic performance of Ni-NCNTs was mainly attributed to the synergetic effect of intercalated Ni with N-doped CNTs at the unique Ni–C interfaces, and the concomitant electronic interaction of Ni and N with C atoms in the interfacial nanoregime. The systematic studies on the synthetic mechanism and structure–activity relationship provide a new insight into the rational design of structural and electronic properties for high-performance Ni-NCNT CEs, as well as into the fundamental understanding of their catalytic mechanism for triiodide reduction.
Graphitic carbon nitride (g-C3N4) has been deemed a promising heterogeneous metal-free catalyst for a wide range of applications, such as solar energy utilization toward water splitting, and its ...photocatalytic performance is reasonably adjustable through tailoring its texture and its electronic and optical properties. Here phosphorus-doped graphitic carbon nitride nanostructured flowers of in-plane mesopores are synthesized by a co-condensation method in the absence of any templates. The interesting structures, together with the phosphorus doping, can promote light trapping, mass transfer, and charge separation, enabling it to perform as a more impressive catalyst than its pristine carbon nitride counterpart for catalytic hydrogen evolution under visible light irradiation. The catalyst has low cost, is environmentally friendly, and represents a potential candidate in photoelectrochemistry.
Over the last decade, significant effort has been devoted to the applications of hierarchically structured porous materials owing to their outstanding properties such as high surface area, excellent ...accessibility to active sites, and enhanced mass transport and diffusion. The hierarchy of porosity, structural, morphological and component levels in these materials is key for their high performance in all kinds of applications. The introduction of hierarchical porosity into materials has led to a significant improvement in the performance of materials. Herein, recent progress in the applications of hierarchically structured porous materials from energy conversion and storage, catalysis, photocatalysis, adsorption, separation, and sensing to biomedicine is reviewed. Their potential future applications are also highlighted. We particularly dwell on the relationship between hierarchically porous structures and properties, with examples of each type of hierarchically structured porous material according to its chemical composition and physical characteristics. The present review aims to open up a new avenue to guide the readers to quickly obtain in-depth knowledge of applications of hierarchically porous materials and to have a good idea about selecting and designing suitable hierarchically porous materials for a specific application. In addition to focusing on the applications of hierarchically porous materials, this comprehensive review could stimulate researchers to synthesize new advanced hierarchically porous solids.
SUMMARY
Vitis amurensis (Shanputao) is the most cold tolerant Vitis species and so is of great interest to grape breeders and producers in areas with low winter temperatures. Here, we report its ...high‐quality, chromosome‐level genome assembly based on a combination of sequence data from Illumina and PacBio platforms, BioNano optical mapping and high‐throughput chromosome conformation Capture (Hi‐C) mapping. The 604.56‐Mb genome contains 32 885 protein‐coding genes. Shanputao was found to share a common ancestor with PN40024 (V. vinifera) approximately 2.17–2.91 million years ago, and gene expansion observed in Shanputao might contribute to the enhancement of cold tolerance. Transcriptome analysis revealed 17 genes involved in cold signal transduction, suggesting that there was a different response mechanism to chilling temperature and freezing conditions. Furthermore, a genome‐wide association study uncovered a phosphoglycerate kinase gene that may contribute to the freezing resistance of buds in the winter. The Shanputao genome sequence not only represents a valuable resource for grape breeders, but also is important for clarifying the molecular mechanisms involved in cold tolerance.
Significance Statement
We provided a high‐quality genome of Vitis amurensis, and found that there were difference response mechanisms to low temperature and cold conditions through transcriptome analysis. We also found that a phosphoglycerate kinase gene might contribute to the cold resistance of buds in the winter.
Versatile electrocatalysis at higher current densities for natural seawater splitting to produce hydrogen demands active and robust catalysts to overcome the severe chloride corrosion, competing ...chlorine evolution, and catalyst poisoning. Hereto, the core‐shell‐structured heterostructures composed of amorphous NiFe hydroxide layer capped Ni3S2 nanopyramids which are directly grown on nickel foam skeleton (NiS@LDH/NF) are rationally prepared to regulate cooperatively electronic structure and mass transport for boosting oxygen evolution reaction (OER) performance at larger current densities. The prepared NiS@LDH/NF delivers the anodic current density of 1000 mA cm−2 at the overpotential of 341 mV in 1.0 m KOH seawater. The feasible surface reconstruction of Ni3S2‐FeNi LDH interfaces improves the chemical stability and corrosion resistance, ensuring the robust electrocatalytic activity in seawater electrolytes for continuous and stable oxygen evolution without any hypochlorite production. Meanwhile, the designed Ni3S2 nanopyramids coated with FeNi2P layer (NiS@FeNiP/NF) still exhibit the improved hydrogen evolution reaction (HER) activity in 1.0 m KOH seawater. Furthermore, the NiS@FeNiP/NF||NiS@LDH/NF pair requires cell voltage of 1.636 V to attain 100 mA cm−2 with a 100% Faradaic efficiency, exhibiting tremendous potential for hydrogen production from seawater.
Herein, core‐shell structured Ni3S2‐FeNi layer double hydroxides (LDH) heterointerfaces are rationally prepared. Abundant hydroxide/sulfide interfaces boost alkaline water oxidation. Impressively, electrochemical results indicate that the in situ formed sulfate layer in LDH shell largely enhances the corrosion resistance of the catalysts in the alkaline salty‐water electrolytes.
The collapse or folding of an individual polymer chain into a nanoscale particle gives rise to single‐chain nanoparticles (SCNPs), which share a soft nature with biological protein particles. The ...precise control of their properties, including morphology, internal structure, size, and deformability, are a long‐standing and challenging pursuit. Herein, a new strategy based on amphiphilic alternating copolymers for producing SCNPs with ultrasmall size and uniform structure is presented. SCNPs are obtained by folding the designed alternating copolymer in N,N‐dimethylformamide (DMF) and fixing it through a photocatalyzed cycloaddition reaction of anthracene units. Molecular dynamics simulation confirms the solvophilic outer corona and solvophobic inner core structure of SCNPs. Furthermore, by adjusting the length of PEG units, precise control over the mean size of SCNPs is achieved within the range of 2.8 to 3.9 nm. These findings highlight a new synthetic strategy that enables enhanced control over morphology and internal structure while achieving ultrasmall and uniform size for SCNPs.
In this study, a novel approach based on amphiphilic alternating copolymers for the synthesis of small‐sized and compact single‐chain nanoparticles (SCNPs) structures is proposed. Precise control over the average size of SCNPs is achieved within the range of 2.8 to 3.9 nm. These findings underscore a new synthetic strategy that enables enhanced manipulation of morphology and internal architecture.
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