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The design and construction of transition metal catalysts with high performance and low-cost characteristics are imperative for liquid hydrogen storage materials. In this study, we prepared ultrathin carbon-stabilized Co-doped CoxOy nanofilms (C–Co/CoxOy NFs) using an ionic liquid/water interface strategy for sodium borohydride (NaBH4) hydrolysis. Owing to its two-dimensional (2D) NF structure and the protective effects of the composite carbon, the C–Co/CoxOy NF catalyst exhibited remarkable activity and durability for hydrogen generation from NaBH4 hydrolysis. The hydrogen generation rate reached 8055 mL·min−1·gCo−1 (5106 mL·min−1·gCat−1) and the catalyst could be recycled more than 20 times, surpassing most reported metal-based catalysts under comparable conditions. In addition, the exceptional 2D Co-based NF structures, with numerous active sites, assisted in the activation of NaBH4 and water molecules, promoting hydrogen production. Thus, these results provided an in-depth understanding of hydrogen generation from NaBH4 hydrolysis, and an effective strategy for rationally designing highly active and durable 2D NF catalysts.

Hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are the two branches of artificial overall water splitting (OWS), in which the reaction efficiency usually depends on different specific catalysts. Although effective bifunctional electrocatalyst for OWS (HER and OER) are highly desired, designing and constructing such suitable materials is full of challenges to overcome several difficulties, involving slow kinetics, differences in catalytic mechanisms, large overpotential values, and low round-trip efficiencies. In this work, we reported a new bifunctional electrocatalyst Ru/RuO2-MoO2 catalyst (RRMC) via a redox solid phase reaction (RSPR) strategy to achieve the high electrocatalytic activity of OWS. Briefly, due to the restricted transport behavior of atoms in solid state precursor, the designed redox reaction occurred between the adjacent part of RuO2 and MoS2, forming Ru/RuO2 hybrid NPs and MoO2 plane. Therefore, the newly formed Ru/RuO2 hybrid NPs and MoO2 plane were tightly combined and used as an electrocatalyst for OWS. Benefiting from the exposed active sites and optimized electronic structure, the RRMC sample annealed at 500 °C (RRMC-500) exhibited low overpotential for HER (18 mV) and for OER (260 mV) at 10 mA cm−2 under alkaline conditions. Especially, a low cell voltage of 1.54 V was required at 10 mA cm−2 under alkaline condition.

Ammonia borane (AB) can be catalytically hydrolyzed to provide hydrogen at room temperature due to its high potentaial for hydrogen storage. Non-precious metal heterogeneous catalysts have broad application in the field of energy catalysis. In this article, catalysts precursor is obtained from Co-Ti-resorcinol-formaldehyde resin by sol–gel method. Co/TiO2@N-C (CTC) catalyst is prepared by calcining the precursor under high temperature conditions in nitrogen atmosphere. Co-CoOx/TiO2@N-C (COTC) is generated by the controllable oxidation reaction of CTC. The catalyst can effectively promote the release of hydrogen during the hydrolytic dehydrogenation of AB. High hydrogen generation at a specific rate of 5905 mL min−1 gCo−1 is achieved at room temperature. The catalyst retains its 85% initial catalytic activity even for its fifth time use in AB hydrolysis. The synergistic effect among Co, Co3O4 and TiO2 promotes the rate limiting step with dissociation and activation of water molecules by reducing its activation energy. The applied method in this study promotes the development of non-precious metals in catalysis for utilization in clean energy sources.

It is especially significant to design and construct high-performance and stable three-dimensional (3D) bifunctional nanoarchitecture electrocatalysts toward overall water splitting. Herein, we have constructed 3D self-supported phosphorus-doped ruthenium-cobalt nanowires on nickel foams (RuCoP/NF) via a simple hydrothermal reaction followed by a low-temperature phosphating reaction. Doping P can not merely enhance the intrinsic activity of electrocatalysts for overall water splitting but at the same time increase electrochemical surface areas (ECSAs) to expose more accessible active sites. As a 3D bifunctional catalyst, RuCoP/NF demonstrates superior performance for HER (44 mV@10 mA cm-2) and OER (379 mV@50 mA cm-2) in 1.0 M KOH electrolyte solution. The overall water-splitting system was assembled using RuCoP/NF as both anode and cathode. Besides, it exhibits a voltage of 1.533 V at a current density of 10 mA cm-2 and long-term durability within 24 h. P-dopant changes the electron structure of Ru and Co, which is conducive to the formation of Ruδ- and Coδ+, resulting in the adjustment of binding H*/OH* and the improvement of the overall water-splitting reaction kinetics. This work provides a facile method to produce heteroatom-doped and high-performance catalysts for efficient overall water splitting.

Low-cost and abundant reserved nonmetallic plasmonic materials have been regarded as a promising substitute of noble metals for photocatalysis and surface-enhanced Raman scattering (SERS). In this ...

Plasmonic Bi2WO6 with strong localized surface plasmon resonance (LSPR) around the 500-1400 region is successfully constructed by electron doping. Oxygen vacancies on W-O-W (V1) and Bi-O-Bi (V2) sites are precisely controlled to obtain Bi2WO6-V1 with LSPR and Bi2WO6-V2 with defect absorption. Density functional theory (DFT) calculation demonstrates that the V1-induced energy state facilitates photoelectron collection for a long lifetime, resulting in LSPR of Bi2WO6. Photoelectron trapping on V1 sites is demonstrated by a single-particle photoluminescence (PL) study, and 93% PL quenching efficiency is observed. With strong LSPR, plasmonic Bi2WO6-V1 exhibits highly selective methane generation with a rate of 9.95 μmol g-1 h-1 during the CO2 reduction reaction (CO2-RR), which is 26-fold higher than 0.37 μmol g-1 h-1 of BiWO3-V2 under UV-visible light irradiation. LSPR-dependent methane generation is confirmed by various photocatalytic results of plasmonic Bi2WO6 with tunable LSPR and different light excitations. Furthermore, the DFT-simulated pathway of CO2-RR and in situ Fourier transform infrared spectra on the surface of Bi2WO6 prove that V1 sites facilitate CH4 generation. Our work provides a strategy to obtain nonmetallic plasmonic materials by electron doping.

Heterojunction formation and morphology control have always been regarded as effective ways to improve the performance of visible-light-driven photocatalysts. In this study, a new facile strategy was applied to synthesize the Z-scheme GO/AgI/Bi2O3 heterojunction, where polyvinyl pyrrolidone (PVP) and γ-methacryloxypropyl trimethoxy silane (KH-570) were used to modulate the morphologies. Methyl orange and tetracycline hydrochloride were chosen as target contaminants to evaluate the photocatalytic properties of samples and the results revealed that 2% GO/AgI/Bi2O3 exhibited the best photocatalytic performance under visible-light irradiation. The enhanced photocatalytic activity can mainly attribute to Z-scheme heterojunction formed by the deposing of AgI and GO as well as the sufficient heterogeneous interfaces resulted from the improved morphology, which have effectively promoted the separation and transfer of electron-hole pairs. To deeply realize the enhanced performance of GO/AgI/Bi2O3 photocatalysts, the reaction kinetics, trapping experiments and photocatalytic mechanism were deduced.

Cyclic ethers are important scaffolds employed in the synthesis of various natural products and pharmaceutical ingredients. A novel free radical-initiated reaction between cyclic ethers and maleimide iodides through C-H activation is developed, avoiding the use of transition metallic catalysts. This method provides a simple approach to derive cyclic ethers, which were further applied in various cross coupling reactions.

Ammonia borane is a promising material for hydrogen storage. In particular, its metal-catalyzed hydrolysis, which can occur under mild conditions and release a high amount (7%–8%) of hydrogen, has attracted considerable recent attention. Most previous studies have sought to improve the hydrolysis rate, leading to a relatively asymmetric research trend, where some potential problems must be overcome before its industrialization. A comprehensive analysis and systematic overview of current research would therefore be helpful to future works. This review first discusses the hydrolysis of ammonia borane in detail. It then summarizes and analyzes recent development of metal catalysts. Some challenges related to the hydrolysis system are also discussed, and finally, some perspectives on emerging issues regarding the future development of this system are provided.

In this work, the pillaring of two layered niobium-based oxides (HNb3 O8 and HNbMoO6 ) with zirconia was investigated in detail. Two novel zirconia-pillared layered metal oxides, zirconia-pillared layered HNb3 O8 and zirconia-pillared layered HNbMoO6 , have been successfully prepared. Both pillared products exhibited a higher thermal stability exceeding 673 K. For the pillaring of layered HNb3 O8 , two different pre-expanding agents, 1-dodecanamine and 1,12-dodecanediamine, were alternatively used, and two kinds of zirconium-pillaring solutions containing zirconium(IV) polyoxocations obtained through two different ways were employed. The 1,12-dodecanediamine-pre-expanded layered intermediate was applicable and 1-dodecanamine-pre-expanded one was not applicable to the intercalation of zirconium(IV) polyoxocations in interlayer regions of the layered niobium-based oxides. More interestingly, the zirconium-pillaring solutions prepared by using an appropriate amount of diethylene glycol as stabilizing agent was advantage for constructing the ordered zirconia-pillared product, whereas the zirconium-pillaring solutions obtained in the case of absence of diethylene glycol seemed not to conduct well an ions-exchange reaction with the alkylamine-pre-expanded layered intermediates. The order degree of zirconia-pillared layered transition metal oxides was closely related to the host sheets. The zirconia-pillared layered HNb3 O8 contained more defects, while the zirconia-pillared layered HNbMoO6 had fewer defects.

Chemical hydrogen storage ammonia borane has attracted extensive attention as a method of efficient utilization of hydrogen energy. The high-efficiency catalysts are the main factor restricting the hydrogen production of ammonia borane. In this paper, the synergistic effect of Co and CoOx supported on graphene (named Co-CoOx @GO-II) promotes the efficient hydrogen production of ammonia borane, and its catalytic hydrogen production rate can reach 5813 mL min-1 gCo -1 at 298 K, the corresponding TOF is 15.33 min-1 . After five stability tests, Co-CoOx @GO-II maintained 65% of its original catalytic performance. The synergy of metal and metal oxide and the defects in the atomic arrangement ensure the catalytic activity, the large specific surface area of graphene ensures the dispersion and fixation. This strategy may provide a possibility to design high-performance transition metal catalysts.

Ammonia borane (AB) is an excellent candidate for the chemical storage of hydrogen. However, its practical utilization for hydrogen production is hindered by the need for expensive noble-metal-based catalysts. Herein, we report Co–Co3O4 nanoparticles (NPs) facilely deposited on carbon dots (CDs) as a highly efficient, robust, and noble-metal-free catalyst for the hydrolysis of AB. The incorporation of the multi-interfaces between Co, Co3O4 NPs, and CDs endows this hybrid material with excellent catalytic activity (rB = 6816 m L H 2 min–1 gCo–1) exceeding that of previous non-noble-metal NP systems and even that of some noble-metal NP systems. A further mechanistic study suggests that these interfacial interactions can affect the electronic structures of interfacial atoms and provide abundant adsorption sites for AB and water molecules, resulting in a low energy barrier for the activation of reactive molecules and thus substantial improvement of the catalytic rate.

TiO2-pillared layered niobic acid was prepared through a stepwise ion-exchange route, in which n-decylamine-pre-swelled layered niobic acid was subjected to react with the pillaring solution containing Ti(IV) polycations obtained by using tetrabutyl titanate as titanium source; then, the as-synthesized Ti(IV) polycation-intercalated layered intermediate was calcined at 723 K in air atmosphere. Powder XRD, FT-IR, SEM, and DR-UV–Vis techniques were employed to characterize the structure and photo-absorption property of the TiO2-pillared layered niobic acid products and their precursors. The catalytic performance of the TiO2-pillared layered products for photodegradation reaction of rhodamine B under ultraviolet light irradiation was also evaluated. The laws of Ti(IV) pillaring solution concentration affecting on the intercalating behavior of Ti(IV) polycations in layered niobic acid, and on the structure and photocatalytic performance of the final TiO2-pillared layered products were revealed. Compared with pure TiO2 or un-pillared layered niobic acid, the binary TiO2-pillared layered niobic acid product exhibited an excellent catalytic activity for the photodegradation reaction of rhodamine B.

It is highly desirable to design high-efficiency stable and low-price catalysts in the electrocatalysis field. Herein, we reported a cobalt phosphide (Co2P)-loaded reduced graphene oxide (rGO) composite catalyst (rGO/Co2P) prepared via the convenient hydrothermal and H2 reduction methods. The rGO/Co2P catalyst reduced at 800 °C (rGO/Co2P-800) shows superior electrocatalytic activities for hydrogen evolution reaction and oxygen evolution reaction in 1.0 M KOH solution, achieving an overpotential of 134 and 378 mV, respectively, at a current density of 10 mA cm–2. Moreover, the catalyst can not only maintain stability for a long time in alkaline solution but also in acid media because of the protection of the rGO layers. The superior performance of this catalyst is attributed to the synergy between the carbon layer and transition-metal phosphides. The Co2P nanoparticles have a high degree of dispersion, which prevents agglomeration, thereby exposing more active sites. Moreover, rGO protects the exposed metal particles while providing more electroconductivity to the material. This work provides an efficient route for the development of bifunctional electrocatalysts with excellent performance and stability, which provides new ideas toward overall water splitting.

Hydrogen is an ideal clean, nontoxic, and abundant energy carrier with incomparable potential development value. At present, the electrochemical hydrogen evolution reaction (HER) and the release of hydrogen from storage materials [e.g., ammonia borane (AB)] are the two most promising clean and efficient hydrogen production methods. The development of a catalyst suitable for both processes will reduce the use of resources and achieve two goals with one product. Although many catalysts have been studied to promote these reactions, unified catalysts for both reactions have rarely been reported. Reported here is the development of a novel hydrogen evolution catalyst based on a uniform self-cross-linked carbon layer loaded with ruthenium phosphide nanoparticles. A simple pyrolysis process produced a material with extraordinary catalytic activity for the HER and also outstanding activity for AB hydrolysis. The catalyst remained stable during both the reactions. This work details an innovative and feasible idea for the design and preparation of various supported catalysts.

The one-step hydroalkylation of benzene to cyclohexylbenzene (CHB) needs to occur on bifunctional metal/zeolite catalysts, and introducing more acid sites to match the metal sites plays a key role in improving the matching of acid/metal sites toward the requirements of benzene hydroalkylation. Herein, we designed and constructed a Si–Al framework coating with extra acid sites outside the surface of the Pd/HBeta catalyst and obtained a zeolite-encaged Pd NP structure (Pd@HBeta). Notably, the Pd@HBeta catalysts achieved excellent catalytic performance with 44.0% CHB selectivity at about 85.0% benzene conversion, which is much higher than that of the Pd/HBeta catalyst with a CHB selectivity of 25.1% at the same benzene conversion. The remarkable increment of CHB selectivity of Pd@HBeta is mainly attributed to the extra acid sites provided by the coated Si–Al framework as well as the increase of the B/L ratio. Moreover, the adsorption capacity of benzene and cyclohexene is greatly improved after introducing extra acid sites by coating the Si–Al framework, which is beneficial for both hydrogenation and alkylation. Further DFT calculations reveal that C6H10 can easily desorb from Pd NPs and migrate to the acidic channel of HBeta in the Pd@HBeta catalyst than that in Pd/HBeta. Our work presents an elegant example of catalytic hydroalkylation selectivity regulation by coating an extra Si–Al framework to enhance the matching of acid/metal balance.

Enyne-allene compounds undergo Myers-Saito cyclization at physiological temperature to generate diradical intermediates that are capable of inducing DNA damage and cell death. The high reactivity of enyne-allene however limits their promising prospect as anticancer agents due to the spontaneous cyclization during storage and delivery. Regulating the cyclization process by taking advantage of the characteristics of a tumor cellular microenvironment, such as employing a low pH value to activate the cyclization process, is thus of essential importance. In this work, a novel enediyne (EDY) system with locked carbonyl groups was specifically designed and synthesized. Unlocking the protected carbonyl groups in the presence of acid would facilitate the rearrangement of propargyl moieties into an allene group, enabling the formation of an enyne-allene structure and occurrence of Myers-Saito cyclization. The pH-dependent diradical generation and DNA-cleavage ability of the designed EDY system were confirmed by electron paramagnetic resonance analysis and DNA gel electrophoresis. A promising cytotoxicity against HeLa cells with half inhibition concentrations (IC50) as low as 1.40 μM was obtained, which was comparable to those of many commercially applied anticancer drugs. Further in vitro experiments revealed that this EDY system induced intracellular DNA damage and subsequently resulted in S-phase arrest and cytotoxicity through programmed apoptosis.

The reasonable design and synthesis of Co-based compounds with superior electrochemical activity and durability have aroused tremendous research interests. Herein, a simple molecular precursor pyrolysis strategy is proposed to fabricate Co4S3, Co9S8 nanoparticles hosted on reduced graphene oxide (rGO) sheets (Co4S3–Co9S8/C/rGO, CSG) using a GO-supported Co-coordination polymer as a precursor for the first time. The synthetic method has the advantages of simple operation and high repeatability. Well-dispersed Co4S3–Co9S8 nanoparticles and abundant interfaces maximize the amount of catalytically active sites. The synergistic adsorption of the reaction intermediates on the interface between Co4S3 and Co9S8 is propitious to electrochemical behavior. The rGO supports with high conductivity and enriched defects speed up the reaction kinetics and effectively inhibit the aggregation of cobalt sulfides. In an alkaline environment, the optimized CSG showed the lowest overpotential (134 mV) at 10 mA cm−2 among the studied materials for the hydrogen evolution reaction. In terms of Li-ion batteries, the hybrid composite CSG exhibited a remarkable reversible capacity of 814 mA h g−1 at a current density of 0.2 A g−1 after 200 cycles. Thus, the present design and engineering strategy may offer an idea for the preparation of other metal sulfides to boost electrochemical storage property.

Hydrogen is a potential clean energy carrier for renewable energy sources. The development of high-efficiency and economical catalysts for hydrogen generation is of great importance. In this work, highly dispersed RuFe alloys were prepared and anchored on the surface of microsphere-type N-doped carbon through a facile impregnation-co-reduction process. The spherical N-doped carbon derived from a resorcinol–formaldehyde resin effectively promoted the surface dispersion of the RuFe alloys and the distribution of catalytic active sites on the support surface. According to the density functional theory simulation, the significant positive synergistic effect originated from the coexistence of Ru and Fe in the alloy and effectively reduced the reaction energy barrier. The alloys with various Ru/Fe ratios were more catalytically active for ammonia borane hydrolysis than their supported single Ru or Fe counterparts. This alloy strategy also effectively improved the utilization ratio and stability of Ru. With the optimized Ru2Fe1/N–C catalyst, an unprecedented hydrogen generation specific rate of 9.4 × 104 mL min−1 gRu−1 was achieved at 298 K. The catalytic activity tended to be stable after five consecutive uses. This work provides a beneficial reference for the design of high-efficiency catalysts for hydrogen generation.

High-index all-dielectric nanostructures with Mie-type resonances have promising applications in building optical nanodevices and metasurfaces. Very recently, great efforts have been made to explore the effective active tuning of Mie-type magnetic resonances via applied voltages, heating, etc. for more sensitive optoelectronic and photothermal applications. Here, we constructed a new platform containing vanadium dioxide (VO2) films and tungsten disulfide (WS2) flakes to realize distinctive active tuning of the collective Mie resonances from silicon nanoparticle (Si NP) clusters and measure the resonance-enhanced local heating precisely. Through increasing the thickness of WS2, we found new type active spectral evolution with high sensitivity during the phase change of VO2. The temperature increase caused by local heating of different Si NP clusters can be determined through both scattering and photoluminescence (PL) measurements with the best thermal resolution less than 1 °C. The proposed platform provides a new way to enhance the active tuning of Mie resonance and detect the local heating sensitively. More importantly, we propose a new mechanism for measuring the photothermal effects of single dielectric nanoparticles for future energy and biomedical applications.

Developing high-efficiency and low-cost catalysts for the hydrogen evolution reaction (HER) and hydrogen generation from chemical hydrogen storage materials are both significant and critical for th...

Construction of tightly bonded interfaces is an indispensable and critical strategy for promoting the catalytic performances of composite structures. In this study, a novel two-dimensional (2D) com...

A series of novel two-dimensional composites between layered HTiNbO5 and graphene were prepared by exfoliation-co-flocculation process, in which HTiNbO5 and graphene oxide were firstly obtained, and the two components were then delaminated into the corresponding dispersed systems, and further the colloidal solution containing the exfoliated HTiNbO5 single layers was mixed with the colloidal suspension containing the ultrathin graphene oxide (GO) nanosheets, followed by adding HCl solution to flocculate, and then by reduction hydrothermally with hydrazine hydrate. The original HTiNbO5, and the composites between HTiNbO5 and reduced graphene oxide (designated as HTiNbO5/rGO) were structurally characterized by means of XRD, FT-IR, Raman spectroscopy, N2 adsorption-desorption technique, TEM and SEM. The photo-absorption property of the samples was measured by using DR-UV-Vis technique. The catalytic performance of the original HTiNbO5 and the HTiNbO5/rGO composites for photodegradation of rhodamine B was also investigated. It was found that upon modifying the layered HTiNbO5 with graphene through the exfoliation-co-flocculation way, its visible light response was effectively enhanced, and its photocatalytic activity was improved, in particular that under visible light irradiation. The photocatalytic activity of the HTiNbO5/rGO composites increased with increasing doping amount of graphene.

Selective hydrogenation of benzene toward cyclohexene is an economically interesting and technically challenging reaction, and catalytic system design is the kernel for selective hydrogenation of b...

Ammonia borane can release abundant hydrogen with an applicable catalyst. In this Article, Co–N-doped carbon spherical catalysts (Co@NCS) were synthesized via the composition of Co-metal–organic fr...

The graphene oxide/bentonite (BG) composites are prepared through graphene oxide (GO) nanosheets successfully intercalated into acid-treated bentonite interlayer and deposited onto external surface. The BG composites exhibit a higher uptake capacity of toluidine blue (TB) dye from water solutions than normal bentonite owing to the synergistic effect between bentonite and GO. The as-prepared composites are characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and N2-sorption analysis. The process parameters affecting the adsorption behaviors such as initial pH, temperature, contact time and initial concentration of dye are systematically investigated. The Langmuir isotherm model fit well with the equilibrium adsorption isotherm data and the maximum adsorption capacity is 458.7 mg·g−1 at pH 8 for BG composites modified using 1% GO. The pseudo-second-order kinetic model well describes the adsorption process of TB onto BG composites. The TB adsorption on BG composites is mainly attributed to ion exchange, electrostatic interaction and intermolecular interactions. The outstanding adsorption performances of composites for the removal of TB dye from water demonstrate its significant potential for environmental applications.

The development of clean fuels for hydrogen utilization will benefit from low-cost and active catalysts to produce hydrogen via hydrolytic dehydrogenation by electrochemical and chemical means. Her...

Rational designs of composites of metal compound nanoparticles and carbonaceous matrixes to improve electrochemical kinetics have attracted growing interests in the application as lithium storage anode materials. In this work, novel three dimensional composites of hollow carbonaceous microspheres-reduced graphene oxide with SnO2 nanoparticles are fabricated by an in situ hybridization method. Benefiting from their particles-hollow sphere-sheets ternary structural characters, these composites revealed excellent electrochemical promoting abilities for Li ion storage. The discharge capacity is up to 944 mA h g–1 after 50 cycles at a current density of 200 mA g–1. After the high-rate charge-discharge cycling at 0.2–2.0 mA g–1, the capacity recovers to 909 mA h g–1 when the current density is reduced back to 200 mA g–1. The carbon matrix with three dimensional structure and appropriate surface by introducing hollow carbonaceous microspheres onto reduced graphene oxide nanosheets as promoter is in favor of excellent ion diffusion channel and high electronic conductivity. The hollow sphere-sheet structures effectively accommodate the huge volume change upon Li ion insertion/extraction. These swimming bladder type composites are promising Li storage anode materials with high capacity and superior rate performance via accelerating kinetics and equilibrium.

The follow-up reaction pathways of the diradical species formed from cycloaromatization of enediynes or enyne-allenes determine their ability of H-abstraction from DNA, significantly affecting their biological activity performance. To gain a deeper understanding of subsequent reaction pathways of the diradical intermediates formed from acyclic enediynes based on maleimide-assisted rearrangement and cycloaromatization (MARACA), a maleimide-based enediyne featuring methylene groups adjacent to the propargyl sites of the terminal alkynes was synthesized through the Sonogashira coupling reaction. Three thermal cyclization products after intramolecular hydrogen atom transfer (HAT) were obtained from the thermolysis experiment and their structures were confirmed by 1D and 2D nuclear magnetic resonance spectroscopic analysis. Density functional theory was employed to analyze the important elementary steps including rearrangement, cycloaromatization, and intramolecular HAT processes toward the formation of the cyclized products, where the low-energy barriers of HAT pathways relative to the formation of diradicals from cycloaromatization were successfully identified. Overall, the HAT processes to consume diradicals intramolecularly have become competitive with that of intermolecular H-abstraction, implying that the DNA-cleavage ability of enediynes can be further boosted once the HAT processes are halted. This study offers a promising direction for designing novel and potent acyclic enediynes for antitumor applications.

Acyclic enediynes are generally inactive under physiological conditions to be used as antitumor agents like their natural enediyne counterparts. A new mechanism named as maleimide-assisted rearrangement and cycloaromatization (MARACA) is uncovered to trigger the reactivity of acyclic enediynes. Through this mechanism, cascade 1,3-proton transfer processes are accelerated with the maleimide moiety at the ene position to enable the acyclic enediynes to undergo cycloaromatization and generate reactive radicals under physiological conditions. Computational studies suggest that the highest energy barrier for MARACA is 26.0 kcal/mol, much lower than that of Bergman cyclization pathway (39.6 kcal/mol). Experimental results show that maleimide-based enediynes exhibit low onset temperature, fast generation of radical species at 37 °C, and much faster reaction in aqueous solution than in nonpolar solvent, which is beneficial to achieve both high reactivity in physiological environment and high stability for storage and delivery in nonpolar media. The generated radical species are capable of causing high percentage of double-strand (ds) DNA cleavage, leading to significant cytotoxicity toward a panel of cancer cell lines with half inhibition concentration down to submicromolar level. Overall, the discovery of the MARACA mechanism provides a platform for designing novel acyclic enediynes with high potency for antitumor applications.

Several microRNAs (miRNAs) have been identified to play roles in adipocyte differentiation. However, little is known about their involvement in the differentiation of ovine intramuscular adipocytes. Here, the role of one such miRNA, miR-340-5p, in ovine adipocyte differentiation was investigated. Stromal vascular (SV) cells were isolated from skeletal muscle tissues of 1-month-old lambs and induced to differentiate into mature adipocytes. miRNA mimics and inhibitors were used for miR-340-5p overexpression and knockdown assays. For overexpression and knockdown of activating transcription factor 7 (ATF7), lentivirus infection was performed. Luciferase reporter assay was performed to determine the relationship between miR-340-5p and ATF7. The expression of adipogenesis marker genes, PPARγ, C/EBPα, FABP4, ADIPOQ, and ACC, and formation of lipid droplets were detected after the overexpression and inhibition of miR-340-5p, or upon overexpression or knockdown of ATF7. miR-340-5p inhibited the expression of the marker genes and the formation of lipid droplets. ATF7 positively regulated the expression of the marker genes and the formation of lipids. Thus, ATF7 is the target of miR-340-5p in sheep. Overall, these findings indicate that miR-340-5p acts as an inhibitor of the differentiation of intramuscular adipocytes by targeting ATF7. Our study provides a new theoretical basis for improving sheep meat quality.

Biomass is important precursor to construct environmental functional materials. Polyaniline/lignosulfonate (PANI-LS) was synthesized through one-step method and used as an adsorbent to remove acid red 94 (AR94) dye from aqueous solution. The PANI-LS was characterized using SEM, XPS, FTIR and N2-sorption analysis. The particles of PANI-LS have been considerably changed after lignosulfonate modified polyaniline. From the batch experiment results, the solution pH plays a significant role during the adsorption. The Langmuir model well describes the adsorption data with the maximum sorption capacity of 10.56 g g−1 (10,560 mg g−1). Pseudo-second-order model can fit well the kinetic data obtained from batch AR94 removal experiments. The adsorption of AR94 onto PANI-LS is a spontaneous and exothermic process in nature. After adsorption, the adsorbate and adsorbent formed a gel-like composite responsible for the superior adsorption efficiency.

Fabrication of core-shells on sheets is considered as an effective strategy to explore novel functional composite materials. Herein, a three-component composite was successfully constructed by dispersing and anchoring carbon-coated Fe3O4 nanoparticle core-shell structures onto reduced graphene oxide (rGO) sheets. Carbonization of glucose polymer formed carbon shells existing between the Fe3O4 particles and rGO sheets. The structure of core-shells placed on rGO sheets formed close connections and high structural stability to the Fe3O4@C-rGO (FCG) composite. Reversible specific capacity up to 884 mA h g−1 at 0.2 C with good recyclability was achieved with FCG as an anode material of lithium-ion batteries. These unique three-dimensional structures of core-shells on sheets are beneficial to enhancing lithium-ion battery storage capacity, cycle stability, and rate performances.

The hybrid nanocomposites ZIF@L composed of Zn-based MOFs (ZIF-8) and lignin were successfully synthesized via a simple one-step method at room temperature. The yield of the hybrid nanocomposites ZIF@L were up to 52% and the synthesis time was greatly shortened. Characterization using FT-IR, XRD, SEM and N2-sorption analysis indicated that ZIF@L composites exhibited rhombic dodecahedral structure such as the parent ZIF-8 synthesized in the absence of lignin and the incorporation of lignin did not destroy the framework integrity of ZIF-8. The ZIF@L composites were used to remove methyl violet (MV). The ZIF@L nanocomposites had a remarkable improvement in adsorption capacity of MV compared with the parent ZIF-8. The modified Langmuir model fitted better the equilibrium data of MV adsorption on the ZIF@L-4 composite and the maximum adsorption capacity of MV is 1001.2 mg g−1. The pseudo-second-order model could describe well the kinetics process of MV dye onto the prepared adsorbents.

In heterogeneous catalysis, especially in the presence of a hydrophilic and hydrophobic mixed solution, the relationship between a nano-/microscale dynamic system and catalytic performance is an unknown but very significant issue. Here, from the result of a coupling liquid–liquid–solid CFD-EDEM (CFD, computational fluid dynamics) simulation as well as a high-speed recording system, we found that it is favorable for the solid catalyst granules to stay in electrolyte water drops to construct instant soft core–shell (SCS) structures in an agitating condition. Different morphologies of Ru catalysts resulting in different water shells are responsible for the different hydrogenation performances. Ru nanosphere (NS) catalysts exhibit higher cyclohexene selectivity (S40 = 66.6%) than other morphologies in benzene-selective hydrogenation. Because the water shells formed around Ru NSs are uniform and in appropriate depth, this benefits the diffusion of cyclohexene and the inhibition of cyclohexane. On the basis of ...

The development of functionalized graphene is of significant importance for the application of graphene in solving current energy and environmental problems. In this work, a series of graphene-based hybrid materials including porous graphene (PG) and carbon nanofibers anchored graphene oxide (GCNFs) were synthesized adopting a controllable solid-phase reaction strategy. Co3O4 nanocrystals (NCs) were used as oxidants to modify and adjust graphene sheets. The PG and GCNFs were formed crucially through the red-ox reaction between graphene and Co3O4 NCs during calcinations. As catalyst for NaBH4 hydrolysis at room temperature, CoOx NCs anchored onto PG and CoOx NCs anchored onto GCNFs provided hydrogen generation specific rates of 1472 mL·min–1·gCo–1 and 2696 mL·min–1·gCo–1, respectively. These outstanding catalytic activities are attributed to the synergistic effect of CoOx NCs and PG/GCNFs. A general strategy was proposed for the oxidative cutting and reconstruction of graphene sheets, and the preparation o...

Developing well-defined nanostructures with superior surface-enhanced Raman scattering (SERS) performance is a critical and highly desirable goal for the practical applications of SERS in sensing and analysis. Here, a SERS-active substrate was fabricated by decorating a MoS2 monolayer with Ag nanowire (NW) and nanoparticle (NP) structures, using a spin-coating method. Both experimental and theoretical results indicate that strong SERS signals of rhodamine 6G (R6G) molecules can be achieved at “hotspots” formed in the Ag NW-Ag NP-MoS2 hybrid structure, with an enhancement factor of 106. The SERS enhancement is found to be strongly polarization dependent. The fabricated SERS substrate also exhibits ultrasensitive detection capabilities with a detection limit of 10–11 M, as well as reliable reproducibility and good stability.

In this study, we successfully anchored 2-aminopyrene-3,4,9,10-tetraone (PYT-NH2), a small organic molecule, onto graphene oxide (GO) and then further chemically reduced it to obtain PYT-NH2/reduced graphene oxide (rGO). We observed that, as an electrode material for high-performance supercapacitor application, PYT-NH2/rGO exhibited higher capability and smaller charge transfer resistance in comparison with PYT-NH2/GO, rGO, and PYT-NH2. The specific capacitances were measured as 326.6 and 229.2 F g–1 for PYT-NH2/rGO and PYT-NH2/GO, respectively, at a current density of 0.5 A g–1 in 1 M sulfuric acid (H2SO4) electrolyte. In addition, we obtained the capacitance of 77.2 F g–1 for PYT-NH2/rGO//activated carbon (AC) at 0.5 A g–1 with an energy density of 15.4 W h kg–1. Moreover, for the fabricated hybrid capacitor, the capacitance retention of 25 000 cycles was nearly 100% at 5 A g–1, thus manifesting excellent electrochemical stability and signaling promising potential in energy storage applications.

A green and efficient preparation of hollow titanium silicalite-1 (TS-1) has been developed by using recycled mother liquid in the post-synthesis treatment. The parent TS-1 was hydrothermally treated with different bases, and hollows appeared in the crystals, due to the controlled desilication from framework. In the presence of tetrapropylammonium cation (TPA + ) during post-synthesis treatment, more hollows were generated, and higher concentration of Ti inside crystals was obtained. The reaction substrates could get sufficient contact with the active centers, and this hollow TS-1 exhibited superior catalytic activity in the propylene epoxidation compared to that of parent sample. When the sample was prepared by using ethanolamine and TPABr as desilication medium, the obtained mother liquid can be reused in the next post-synthesis treatment. In the recycling process, the added amount of ethanolamine and TPABr was only 50% and 25% of the amount for the first post-synthesis treatment, respectively. Even the mother liquid was recycled eight times, all obtained hollow TS-1 showed similar catalytic activity in the propylene epoxidation to that of the sample prepared by using TPAOH as desilication medium. This process can almost eliminate the discharge of waste liquid to achieve a sustainable development, and save the cost of hollow TS-1 production.

The conventional Bergman pathway of enediynes to generate diradicals has to overcome a high reaction barrier, which limits the design of enediynes embedded inside a highly strained ring. Here, we proposed an alternative reaction mechanism. By converting the originally inactive enediyne into enyne-allene through possible 1,4-Michael addition, the low barrier Myers-Saito cyclization was triggered. Although direct addition of water or methanol was impossible due to high activation barrier, the 1,4-Michael addition was feasible with the assistance of intermolecular proton transfer at physiological temperature. This mechanism opens a new strategy in the design of structurally simple acyclic enediynes.

Suberin poly phenolic is an important component of healing tissue. We aimed to develop a new method to accelerate wound healing of harvested muskmelons. In this study, the plants and fruits of muskmelons were sprayed with 0.1 % chitosan four times during fruit development to evaluate the effect of chitosan treatment on wound healing of harvested muskmelons. The results showed that preharvest chitosan sprays reduced the weight loss and disease index of harvested muskmelons during healing. Chitosan sprays also accelerated the deposition of suberin poly phenolic at wound sites of harvested muskmelons during healing. The treatment increased the activities of phenylalanine ammonia-lyase and cinnamate-4-hydroxylase, and promoted the accumulation of cinnamic acid, caffeic acid, ferulic acid, p-coumaric acid, total phenols and flavonoids at wound sites. We suggest that preharvest chitosan sprays activated phenylpropanoid metabolism, promoted the deposition of suberin poly phenolic at wound sites of harvested muskmelons.

The central task in efficient heterogeneous catalysis process lies in exploring catalysts with simultaneous superior performance and low cost. The construction of active sites based on low content of noble and non-noble metals is regard as a promising but challenging strategy for the rational design of catalysts. Herein, we report that a NiRu alloy anchored on surface of nitrogen-doped carbon-coated titanium dioxide showed the highest catalytic activity (2.51 × 105 mL·min−1·gRu−1) for NH3BH3 hydrolysis at 298 K. The unprecedented activity is beyond previous reports. The alloy effect in NiRu alloy and the metal-support interaction between alloy and composite support tune the surface d charge. From experimental and DFT simulation results, the optimized surface d charge is positively corresponding to the low active energy in water and ammonia borane molecule activation. This study opens up a new way for the rational design of highly effective non-noble metal heterogeneous catalysts.

The development of high-efficient and economical catalysts is a challenging problem for the utilization of sustainable hydrogen energy. Alloying noble metal with non-noble metal is a promising strategy to achieve high catalytic activity and stability of catalysts. Herein, highly dispersed Ru-Cu alloy nanoparticles were successfully fabricated via solid-surfaces-organic-pyrolysis on N-doped carbon coating TiO2 towards hydrogen evolution in NH3BH3 hydrolysis. Ru-Cu alloys with various molar ratios exhibit markedly enhanced catalytic activity than monometallic counterparts. The optimized Ru0.6Cu0.4/TiO2@C-N catalyst achieves an excellent TOF of 626 molH2 molRu−1 min−1 at room temperature. Experimental analysis and DFT calculation reveal the existence of ensemble-boosting effect between Ru and Cu. Multiatomic active sites in alloy significantly promote hydrogen evolution in NH3BH3 hydrolysis. This research provides further understanding of catalytic mechanism and the rational design of high-efficient and economical bimetallic nanocatalysts.

The searching for novel catalysts is of importance for the industrial application of the green synthesis of adipic acid in the absence of toxic or dangerous oxidants or solvents. Herein, an Anderson-type polyoxometalate, [Ni(OH)6W6O18]4−, has been firstly employed as a highly effective oxidation catalyst for green synthesis of adipic acid with aqueous H2O2 as oxygen donor. Under the organic solvent- and phase-transfer catalyst-free conditions, excellent yields of adipic acid up to 95.6% and 90.9% could be obtained with cyclohexanediol and cyclohexene as substrates, respectively. Based on the spectroscopy characterization and density functional theory calculation, the detailed catalytic mechanism at the atomic level is proposed for this green catalytic synthesis method.

High performance heterogeneous catalysts are strongly dependent on the availability of interfaces. However, the formation of these interfaces is often compromised by harsh synthetic conditions, low structural controllability, and limited active sites. Here, we report that a facile in-situ growth of copper nanoparticles (NPs) in a cobalt metal-organic framework (Cu NPs-Co MOF), via solvothermal and moderate activation process, leads to catalysts with abundant dual sites at their interface. The optimized Cu0.5@Co0.5-MOF/5 composite exhibits outstanding performances with a turnover frequency of 129.8 min−1, stability of over 10 cycles and low activation energy of 26.5 kJ·mol−1 for ammonia borane hydrolysis. Such a prominent activity is achieved by the intimate synergy of Cu°-Co2+ atomic ensembles at the interface, which substantially boost the reaction rate by catalyzing ammonia borane and water in a synchronized manner. This research opens up a new pathway for the rational design of non-noble metal heterogeneous catalysts by fabricating metal NPs-MOFs interfaces at nanoscale.