Ordered Hierarchical Mesoporous/Microporous Carbon Derived from Mesoporous Titanium‐Carbide/Carbon Composites and its Electrochemical Performance in Supercapacitor

Novel ordered hierarchical mesoporous/microporous carbon (OHMMC) derived from mesoporous titanium‐carbide/carbon composites was prepared for the first time by synthesizing ordered mesoporous nanocrystalline titanium‐carbide/carbon composites, followed by chlorination of titanium carbides. The mesostructure and microstructure can be conveniently tuned by controlling the TiC contents of mesoporous TiC/C composite precursor, and chlorination temperature. By optimal condition, the OHMMC has a high surface area (1917 m²g^?1), large pore volumes (1.24 cm³g^?1), narrow mesopore‐size distributions (centered at about 3 nm), and micropore size of 0.69 and 1.25 nm, and shows a great potential as electrode for supercapacitor applications: it exhibits a high capacitance of 146 Fg^?1 in noaqueous electrolyte and excellent rate capability. The ordered mesoporous channel pores are favorable for retention and immersion of the electrolyte, providing a more favorable path for electrolyte penetration and transportation to achieve promising rate capability performance. Meanwhile, the micropores drilled on the mesopore‐walls can increase the specific surface area to provide more sites for charge storage.     

介孔碳纳米材料的制备及其在药物传递方面的应用进展

新型功能性纳米材料在设计和制备技术方面的进步为纳米医学的发展提供了很大的机遇。在过去十年中,介孔碳纳米材料在制备和应用方面获得了巨大的进步。作为一种新型无机材料体系,介孔碳纳米材料结合了介孔的结构以及碳质组成的特点,显示出不同于传统介孔二氧化硅以及其它一些碳基材料体系(碳纳米管、石墨烯、富勒烯等)的优越特性。介孔碳纳米材料在药物的吸附与控释、光热治疗、协同治疗、肿瘤细胞的荧光标记、催化、生物传感、生物大分子的分离等诸多领域表现出其他多孔材料难以达到的优越性和应用潜力。本文对介孔碳纳米材料的制备和修饰技术进行介绍,重点关注介孔碳纳米颗粒在药物负载和光热控释方面的应用,最后对介孔碳纳米材料在生物医学领域的应用前景和所面临的关键问题进行讨论。     

Egg‐Derived Mesoporous Carbon Microspheres as Bifunctional Oxygen Evolution and Oxygen Reduction Electrocatalysts

A bifunctional evolution reaction (OER) and oxygen reduction reaction (ORR) electrocatalysts are developed, based on codoped mesoporous carbon microspheres from ecofriendly biomass of eggs without the introduction of extrinsic dopants, via a facile and high‐throughput spray‐drying process. The obtained egg‐derived mesoporous carbon microspheres (egg‐CMS) present large specific surface area and high pore volume, as well as abundant dopant types including nitrogen, phosphorous, and iron that are originated from the innate protein and small organic molecule contents. When fabricated as OER or ORR catalysts, these egg‐CMS exhibit low onset potentials, high current densities, small Tafel slopes, and excellent stabilities. As a proof‐of‐concept, a rechargeable Zn‐air battery is demonstrated using the high‐active egg‐CMS as a bifunctional OER and ORR catalyst, suggesting the capability of utilizing full biomass materials for efficient energy storage and utilization.     

Short‐Range Order in Mesoporous Carbon Boosts Potassium‐Ion Battery Performance

The adequate potassium resource on the earth has driven the researchers to explore new‐concept potassium‐ion batteries (KIBs) with high energy density. Graphite is a common anode for KIBs; however, the main challenge faced by KIBs is that K ions have the larger size than Li and Na ions, hindering the intercalation of K ions into electrodes and thus leading to poor rate performance, low capacity, and cycle stability during the potassiation and depotassiation process. Herein, an amorphous ordered mesoporous carbon (OMC) is reported as a new anode material for high‐performance KIBs. Unlike the well‐crystallized graphite, in which the K ions are squeezed into the restricted interlayer spacing, it is found that the amorphous OMC possesses larger interlayer spacing in short range and fewer carbon atoms in one carbon‐layers cluster, making it more flexible to the deformation of carbon layers. The larger interlayer spacing and the unique layered structure in short range can intercalate more K ions into the carbon layer, accommodate the increase of the interlayer spacing, and tolerate the volume expansion, resulting in a battery behavior with high capacity, high rate capability, and long cycle life.     

Li4Ti5O12 Nanoparticles Embedded in a Mesoporous Carbon Matrix as a Superior Anode Material for High Rate Lithium Ion Batteries

A mesoporous Li₄Ti₅O₁₂/C nanocomposite is synthesized by a nanocasting technique using the porous carbon material CMK‐3 as a hard template. Modified CMK‐3 template is impregnated with Li₄Ti₅O₁₂ precursor, followed by heat treatment at 750 °C for 6 h under N₂. Li₄Ti₅O₁₂ nanocrystals of up to several tens of nanometers are successfully synthesized in micrometer‐sized porous carbon foam to form a highly conductive network, as confirmed by field emission scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, Raman spectroscopy, and nitrogen sorption isotherms. The composite is then evaluated as an anode material for lithium ion batteries. It exhibits greatly improved electrochemical performance compared with bulk Li₄Ti₅O₁₂, and shows an excellent rate capability (73.4 mA h g^?1 at 80 C) with significantly enhanced cycling performance (only 5.6% capacity loss after 1000 cycles at a high rate of 20 C). The greatly enhanced lithium storage properties of the mesoporous Li₄Ti₅O₁₂/C nanocomposite may be attributed to the interpenetrating conductive carbon network, ordered mesoporous structure, and the small Li₄Ti₅O₁₂ nanocrystallites that increase the ionic and electronic conduction throughout the electrode.     

Post Iron Decoration of Mesoporous Nitrogen‐Doped Carbon Spheres for Efficient Electrochemical Oxygen Reduction

Iron–nitrogen–carbon (Fe–N–C) catalysts are considered as the most promising nonprecious metal catalysts for oxygen reduction reactions (ORRs). Their synthesis generally involves complex pyrolysis reactions at high temperature, making it difficult to optimize their composition, pore structure, and active sites. This study reports a simple synthesis strategy by reacting preformed nitrogen‐doped carbon scaffolds with iron pentacarbonyl, a liquid precursor that can effectively form active sites with the nitrogen sites, enabling more effective control of the catalyst. The resultant catalyst possesses a well‐defined mesoporous structure, a high surface area, and optimized active sites. The catalysts exhibit high ORR activity comparable to that of Pt/C catalyst (40% Pt loading) in alkaline media, with excellent stability and methanol tolerance. The synthetic strategy can be extended to synthesize other metal–N–C catalysts.     

Heteroatom‐Doped Mesoporous Hollow Carbon Spheres for Fast Sodium Storage with an Ultralong Cycle Life

Carbon materials have attracted significant attention as anode materials for sodium ion batteries (SIBs). Developing a carbon anode with long‐term cycling stability under ultrahigh rate is essential for practical application of SIBs in energy storage systems. Herein, sulfur and nitrogen codoped mesoporous hollow carbon spheres are developed, exhibiting high rate performance of 144 mA h g^?1 at 20 A g^?1, and excellent cycling durability under ultrahigh current density. Interestingly, during 7000 cycles at a current density of 20 A g^?1, the capacity of the electrode gradually increases to 180 mA h g^?1. The mechanisms for the superior electrochemical performance and capacity improvement of the cells are studied by electrochemical tests, ex situ transmission electron microscopy, X‐ray diffraction, X‐ray photoelectron spectroscopy, and Raman analysis of fresh and cycled electrodes. The unique and robust structure of the material can enhance transport kinetics of electrons and sodium ions, and maintain fast sodium storage from the capacitive process under high rate. The self‐rearrangement of the carbon structure, induced by continuous discharge and charge, lead to the capacity improvement with cycles. These results demonstrate a new avenue to design advanced anode materials for SIBs.     

Polysulfide Confinement and Highly Efficient Conversion on Hierarchical Mesoporous Carbon Nanosheets for Li–S Batteries

Lithium–sulfur (Li–S) batteries have attracted increasing attention due to their extremely high theoretical specific capacity and a promising power density. However, practical applications of Li–S batteries are still limited by the relatively low performance, owing to poor conductivity of sulfur itself and discharge products (Li₂S/Li₂S₂) as well as the shuttle effect of the intermediate polysulfide. Herein, honeycomb‐like mesoporous Co, N‐doped carbon nanosheets (MC‐NS) with a high specific surface area and abundant defects are developed which, simultaneously enable polysulfide confinement and highly efficient conversion. Moreover, density functional theory calculations and experiments show that the Co‐N‐C catalytic site as well as defects on the carbon skeleton of the MC‐NS facilitate high efficiency in suppressing the shuttle effect of polysulfides. In situ Raman spectra further demonstrate the enhancement of adsorption ability and conversion efficiency of polysulfides on this host. As a result, the MC‐NS enables much increased specific capacity and cycling stability of Li–S batteries. This work provides a useful strategy for realizing practical applications of high‐performance Li–S batteries.     

Optical Detection of E. coli Bacteria by Mesoporous Silicon Biosensors

A label-free optical biosensor based on a nanostructured porous Si is designed for rapid capture and detection of Escherichia coli K12 bacteria, as a model microorganism. The biosensor relies on direct binding of the target bacteria cells onto its surface, while no pretreatment (e.g. by cell lysis) of the studied sample is required. A mesoporous Si thin film is used as the optical transducer element of the biosensor. Under white light illumination, the porous layer displays well-resolved Fabry-Pérot fringe patterns in its reflectivity spectrum. Applying a fast Fourier transform (FFT) to reflectivity data results in a single peak. Changes in the intensity of the FFT peak are monitored. Thus, target bacteria capture onto the biosensor surface, through antibody-antigen interactions, induces measurable changes in the intensity of the FFT peaks, allowing for a ''real time'' observation of bacteria attachment.The mesoporous Si film, fabricated by an electrochemical anodization process, is conjugated with monoclonal antibodies, specific to the target bacteria. The immobilization, immunoactivity and specificity of the antibodies are confirmed by fluorescent labeling experiments. Once the biosensor is exposed to the target bacteria, the cells are directly captured onto the antibody-modified porous Si surface. These specific capturing events result in intensity changes in the thin-film optical interference spectrum of the biosensor. We demonstrate that these biosensors can detect relatively low bacteria concentrations (detection limit of 10⁴ cells/ml) in less than an hour.     

Cu,Co‐Embedded N‐Enriched Mesoporous Carbon for Efficient Oxygen Reduction and Hydrogen Evolution Reactions

Rational synthesis of hybrid, earth‐abundant materials with efficient electrocatalytic functionalities are critical for sustainable energy applications. Copper is theoretically proposed to exhibit high reduction capability close to Pt, but its high diffusion behavior at elevated fabrication temperatures limits its homogeneous incorporation with carbon. Here, a Cu, Co‐embedded nitrogen‐enriched mesoporous carbon framework (CuCo@NC) is developed using, a facile Cu‐confined thermal conversion strategy of zeolitic imidazolate frameworks (ZIF‐67) pre‐grown on Cu(OH)₂ nanowires. Cu ions formed below 450 °C are homogeneously confined within the pores of ZIF‐67 to avoid self‐aggregation, while the existence of Cu? N bonds further increases the nitrogen content in carbon frameworks derived from ZIF‐67 at higher pyrolysis temperatures. This CuCo@NC electrocatalyst provides abundant active sites, high nitrogen doping, strong synergetic coupling, and improved mass transfer, thus significantly boosting electrocatalytic performances in oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER). A high half‐wave potential (0.884 V vs reversible hydrogen potential, RHE) and a large diffusion‐limited current density are achieved for ORR, comparable to or exceeding the best reported earth‐abundant ORR electrocatalysts. In addition, a low overpotential (145 mV vs RHE) at 10 mA cm^?2 is demonstrated for HER, further suggesting its great potential as an efficient electrocatalyst for sustainable energy applications.     

Morin Flavonoid Adsorbed on Mesoporous Silica,a Novel Antioxidant Nanomaterial

Morin (2´,3, 4´,5,7-pentahydroxyflavone) is a flavonoid with several beneficial health effects. However, its poor water solubility and it sensitivity to several environmental factors avoid its use in applications like pharmaceutical and cosmetic. In this work, we synthetized morin-modified mesoporous silica nanoparticles (AMSNPs-MOR) as useful material to be used as potential nanoantioxidant. To achieve this, we characterized its adsorption kinetics, isotherm and the antioxidant capacity as hydroxyl radical (HO•) scavenger and singlet oxygen (¹O₂) quencher. The experimental data could be well fitted with Langmuir, Freundlich and Temkin isotherm models, besides the pseudo-second order kinetics model. The total quenching rate constant obtained for singlet oxygen deactivation by AMSNPs-MOR was one order of magnitude lower than the morin rate constant reported previously in neat solvents and lipid membranes. The AMSNPs-MOR have good antioxidant properties by itself and exhibit a synergic effect with morin on the antioxidant property against hydroxyl radical. This effect, in the range of concentrations studied, was increased when the amount of morin adsorbed increased.     

Mesoporous silica nanoparticles in nanotechnology

Mesoporous silica nanoparticles (MSNs) are a versatile drug delivery system that can be used for loading of different guest molecules such as peptides, proteins, anticancer agents, and genetic material. MSNs are considered promising drug carriers due to their tuneable particle size, pore structure, and surface functionalization. Thus, MSNs provide opportunities for their effective application in a wide variety of fields. In the current review, we discuss both conventional and advanced MSNs synthesis methods, including their applications for drug delivery, gatekeepers, and biosensors. In addition, the research progress in biocompatibility, cytotoxicity, and internalization mechanisms is reported.     

Graphitic Nanoshell/Mesoporous Carbon Nanohybrids as Highly Efficient and Stable Bifunctional Oxygen Electrocatalysts for Rechargeable Aqueous Na–Air Batteries

Efficient and cost‐effective bifunctional electrocatalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are of vital importance in energy conversion and storage devices. Despite the recent progress in bifunctional oxygen electrocatalysts, their unbalanced and insufficient OER and ORR activities has continued to pose challenges for the practical application of such energy devices. The design of highly integrated, high‐performance, bifunctional oxygen electrocatalysts composed of highly graphitic nanoshells embedded in mesoporous carbon (GNS/MC) is reported. The GNS/MC exhibits very high oxygen electrode activity, which is one of the best performances among nonprecious metal bifunctional oxygen electrocatalysts, and substantially outperforms Ir‐ and Pt‐based catalysts. Moreover, the GNS/MC shows excellent durability for both OER and ORR. In situ X‐ray absorption spectroscopy and square wave voltammetry reveal the roles of residual Ni and Fe entities in enhancing OER and ORR activities. Raman spectra indicate highly graphitic, defect‐rich nature of the GNS/MC, which can contribute to the enhanced OER activity and to high stability for the OER and ORR. In aqueous Na–air battery tests, the GNS/MC air cathode‐based cell exhibits superior performance to Ir/C‐ and Pt/C‐based batteries. Significantly, the GNS/MC‐based cell demonstrates the first example of rechargeable aqueous Na–air battery.     

Carbon metabolism in model microbial systems from a temperate salt marsh.

The metabolism of a saltwater leachate of 14C-labeled Spartina alterniflora was examined in laboratory systems using mixed, salt marsh microbial communities and, by addition of appropriate antibiotics, communities with bacteria or eukaryotes inhibited. Label uptake was more rapid in the systems with bacteria alone and with the mixed microbial community than with fungi alone. Mineralization of the added label was more extensive in the mixed and bacterial systems, whereas the fungi appear more efficient at converting the label into particulate biomass. Particulate biomass production efficiencies ranged from a high of 0.82 for the fungal system to 0.21 in the mixed community, with the bacterial system giving an intermediate value of 0.54. The presence of protozoa and microcrustaceans in the mixed system appears to account for an increase in the mineralization of the label assimilated. Additional experiments with whole labeled Spartina, a leachate from Spartina, and Spartina after leaching revealed that the seawater-soluble portions of the plants were attacked most rapidly by the microbial community.     

Studies on Choanephoraceae. IV. Carbon requirements

Summary The comparative utilization of different carbon compounds byBlakeslea trispora, Choanephora cucurbitarum, Choanephora infundibulifera, Choanephora conjuncta, Choanephora heterospora andChoanephora circinans was studied under controlled conditions. Of the monosaccharides, rhamnose and sorbose were poorly utilized, while the rest of them were favourably utilized by all the species. Amongst the disaccharides, maltose proved to be the best. Sucrose, lactose and melibiose were poor sources. Raffinose, the only trisaccharide used supported poor growth of all the species. Of the polysaccharides used, starch and glycogen supported good growth of all the species. Dextrin and inulin were used in varying degrees by the present species. Both sorbitol and mannitol supported growth of the fungi in varying degrees. All the organic acids used, proved to be valueless in the present investigation.In some cases good sporulation was accompanied with good or moderate growth. No correlation with regard to the growth and sporulation could be established. The final pH of media showed a tendency to drift towards the alkaline side in most of the cases.     

Preparation of Mesoporous Nano-Hydroxyapatite Using a Surfactant Template Method for Protein Delivery

Mesoporous nano-hydroxyapatite (n-HA) has gained more and more attention as drug storage and release hosts.The aim of this study is to observe the effect of the ratio of surfactant to the theoretical yield of HA on the mesoporous n-HA,then to reveal the effect of the mesoporous nanostrueture on protein delivery.The mesoporous n-HA was synthesized using the wet precipitation in the presence of cetyltrimethylammonium bromide (CTAB) at ambient temperature and normal atmospheric pressure.The morphology,size,crystalline phase,chemical composition and textural characteristics of the product were well characterized by X-ray Powder Diffraction (XRD),Fourier Transform Infrared Spectroscopy (FTIR),Scanning Electron Microscopy (SEM),Transmission Electron Microscopy (TEM),Dynamic Light Scattering (DLS) and N2 adsorption/desorption,respectively.The protein adsorption/release studies were also carried out by using Bovine Serum Albumin (BSA) as a model protein.The results reveal that the mesoporous n-HA synthesized with CTAB exhibits high pure phase,low crystallinity and the typical characteristics of the mesostructure.The BSA loading increases with the specific surface area and the pore volume of n-HA,and the release rates of BSA are different due to their different pore sizes and pore structures,n-HA synthesized with 0.5％ CTAB has the highest BSA loading and the slowest release rate because of its highest surface area and smaller pore size.These mesoporous n-HA materials demonstrate a potential application in the field of protein delivery due to their bioaetive,biocompatible and mesoporous properties.