Search

The construction of heterostructures with engineered phases and interfaces is crucial to essentially reform the oxygen evolution reaction (OER) in water splitting. Herein, a fine ion exchange route combined with subsequent phosphorization and sulfurization processes is developed for the controllable synthesis of a novel MoPxSy@NiFePxSy@NPS-C hierarchical heterostructure. The well-designed MoPxSy@NiFePxSy@NPS-C consists of multiple components (NiFePx, NiFeSy, and MoPxSy) anchored on N,P,S co-doped carbon, forming abundant engineered phases and interfaces, which have shown an impressive OER activity and long-term stability. The density functional theory (DFT) calculations have revealed the enhanced electronic interactions and favorable charge transfer at engineered interfaces. The introduction of N, P, and S in the engineered phases helps to tune the electronic structure of the heterostructure and promote the adsorption and desorption of the OER intermediates over the heterostructure because of the lowered energy barrier involved in the electrocatalytic OER. The new approach to multiple engineered interfaces and multiple phases may pave a way for construction of high performance heterostructure electrocatalysts. [ABSTRACT FROM AUTHOR]

A cation exchange strategy is proposed to convert layered Ti3C2–Na–TiO2 MXene nanofibers into Ti3C2–Co–TiO2 MXene nanoparticle arrays with open-layered 3D structure and numerous heterogeneous interfaces, which deliver excellent oxygen evolution reaction (OER) activity. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have diverse structures and compositions, inspiring the boundless enthusiasm and creativity of researchers in the field of electromagnetism. The synthesis of MOF-derived nanomaterials for electromagnetic wave (EMW) absorption with ultrathin matching thickness (below 1.6 mm) is highly desired and challenging. Here, we demonstrate a general synthesis strategy for metal (Co, Ni, Fe)-based MOFs, which transformed into metal/metal-oxide nanoparticles (NPs) of being coated by nitrogen (N)-doped graphitized carbon. The obtained carbon-coated NPs show excellent EMW absorption properties. Specifically, Co-based MOFs are pyrolyzed into rhombic dodecahedrons with numerous ultrasmall Co NPs coated by N-doped carbon (Co-NC core–shell NPs). The synthesized Co-NC core–shell NPs possess a unique porous structure, abundant defects, and doped N heteroatoms, resulting in good magnetic loss (eddy current loss), dielectric loss (multiple reflections, interfacial polarization, conduction loss), and impedance matching. Therefore, the Co-NC core–shell NPs exhibit an excellent EMW absorption property with a very strong reflection loss of −56.5 dB at a matching thickness of only 1.58 mm. The effective absorption bandwidth (EAB) is 4.4 GHz. In addition, the EAB between 1 and 5 mm in thickness is up to 13.2 GHz, which already includes all C bands and X bands, even the absolute S bands and Ku bands. This work provides an avenue to design high-performance EMW absorption devices based on MOF-derived nanomaterials. [ABSTRACT FROM AUTHOR]

Sodium‐metal batteries (SMBs) employing transition‐metal‐free cathodes are of great importance for energy storage applications that require low cost and high energy density. A strategy to enhance the energy density of transition‐metal‐free‐cathode SMBs by transforming the electrolyte from a dead mass to an energy‐storage contributor is reported. NaI is used for the partial substitution of NaClO4 in the electrolyte and thus provides the additional electrochemistry of I3−/I− redox couple to enhance battery performance. Graphene oxide (GO) encapsulated mesoporous (10 nm) carbon spheres (N‐MCS@GO) that are nitrogen‐doped (15.71 at%) are fabricated as the cathode for the I3−/I− redox enhanced SMBs. It is experimentally demonstrated that: the mesoporous structure increases the capacitive energy storage by providing a substantial interface that enhances the electrochemistry of I3−/I− redox couples; and encapsulation of the mesoporous carbon spheres with GO suppresses self‐discharge and increases Coulombic efficiencies from 70.4% to 91.9%. In full‐cell configuration, N‐MCS@GO working with the NaI‐activated electrolyte can deliver a capacity of 279.6 mAh g−1 with an energy density of 459.2 Wh kg−1 in 0.5–3 V at 200 mA g−1. I3−/I− redox in the full cell maintains its activity without obvious decay after 1000 cycles at 1 A g−1, highlighting the practical application of the I3−/I− redox enhanced SMBs. [ABSTRACT FROM AUTHOR]

Thermoelectric properties and phase evolution have been studied in biphasic Ti-Ni-Sn materials containing full-Heusler TiNi2Sn embedded within half-Heusler thermoelectric TiNiSn. Materials, prepared by levitation induction melting followed by annealing, were of the nominal starting composition of TiNi1+xSn, with x between 0.00 and 0.25. Phases and microstructure were determined using synchrotron X-ray diffraction and optical and electron microscopy. The full-Heusler phase is observed to be semi-coherent with the half-Heusler majority phase. Differential thermal analysis was performed to determine melting temperatures of the end-member compounds. The thermal conductivity is reduced with the introduction of a dispersed, full-Heusler phase within the half-Heusler material. This leads to an increased thermoelectric figure of merit, ZT, from 0.35 for the stoichiometric compound to 0.44 for TiNi1.15Sn. Beyond x=0.15 ZT decreases due to a rise in thermal conductivity. Density functional theory calculations using hybrid functionals were performed to determine band alignments between the half- and full-Heusler compounds, as well as comparative energies of formation. The hybrid functional band structure of TiNiSn is presented as well. [ABSTRACT FROM AUTHOR]

Zone melting purification experiments have been carried out on the clathrate, Ba[sub 8]Ga[sub 16]Ge[sub 30]. The impurities present have been identified and their approximate concentrations measured. Trace impurities were determined to be approximately 240 parts per million (ppm) in the most impure sample to 17 ppm in the most pure sample. The temperature-dependent Seebeck coefficient, thermal conductivity, and electrical conductivity are reported as a function of sample purity as well as the room-temperature Hall coefficient. Microprobe analysis suggests that the samples are nonstoichiometric with excess Ge relative to Ga, and there are indications of the presence of defects. Single-crystal x-ray investigations as well as synchrotron powder diffraction measurements support the presence of defects, but the x-ray data cannot accurately determine the relative amounts of Ga and Ge. Band-structure calculations in the generalized gradient approximation show that the measured Hall and Seebeck coefficients are consistent with a defect lattice of approximate stoichiometry Ba[sub 8]Ga[sub 14]Ge[sub 31]. Although the figure of merit (ZT) is found to be the highest for the purest sample, the dominant contribution to transport is conjectured to arise from deviations from the ideal stoichiometry and not impurities. [ABSTRACT FROM AUTHOR]

Density functional calculations in the generalized gradient approximation are used to study the transport properties of the clathrates Ba[sub 8]Ga[sub 16]Ge[sub 30], Sr[sub 8]Ga[sub 16]Ge[sub 30], Ba[sub 8]Ga[sub 16]Si[sub 30], and Ba[sub 8]In[sub 16]Sn[sub 30]. The band structures of these clathrates indicate that they are all semiconductors. Seebeck coefficients, conductivities and Hall coefficients are calculated, to assess the effects of carrier concentration on the quantity S[sup 2]σ/τ (where S is the Seebeck coefficient, σ is the conductivity, and τ the electron relaxation time) which is proportional to the thermoelectric power factor. In each compound we find that both p- and n-doping will significantly enhance the thermoelectric capabilities of these compounds. For p-doping, the power factors of all four clathrates are of comparable magnitude and have similar temperature dependence, while for n-doping we see significant variations from compound to compound. We estimate that room-temperature ZT values of 0.5 may be possible for optimally n-doped Sr[sub 8]Ga[sub 16]Ge[sub 30] or Ba[sub 8]In[sub 16]Sn[sub 30]; at 800 K ZT values as large as 1.7 may be possible. For single crystals of high quality, with substantially increased scattering times, the power factor of these materials will be significantly higher. Recent experiments are reviewed in the light of these calculations. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Prolonged exposure of colorless dry sodalite to alkali vapor causes the material to gradually turn blue, dark blue, and finally black. The blue color observed at low sodium uptake appears because the absorbed sodium atoms are spontaneously ionized. The electron produced by ionization is shared by the four sodium ions present in the sodalite cage (three initially there and the fourth originating from the absorbed atom). The color center created in this way is represented by the formula (Na+)4eF3-. Here, e stands for the electron and F3- for the negatively charged frame surrounding a zeolite cage. At the highest loading, when each cage contains an absorbed alkali atom, the color centers are arranged in a body-centered cubic lattice, allowing the electrons associated with the centers to form bands. This may explain the black color observed at high concentration. In this paper we present measurements of the absorption coefficient of the black sodalite for photon energies between 0 and 3 eV, and interpret them by performing one-electron band structure calculations for a fully loaded compound. These calculations deal only with the ‘‘solvated’’ electrons. The effect of the other electrons is taken into account through an empirical potential energy representing the interaction of a solvated electron with the zeolite frame. Because of this we study only the bands formed by the electrons of the color centers. Since the gap in the electron energy bands of the dry sodalite is over 6 eV, the color of the black sodalite is controlled by the solvated-electron bands formed in this gap. The measured spectrum has a threshold of about 0.6 eV which seems to suggest that the system has a gap in the electronic structure and is therefore a semiconductor. The calculations indicate, however, that, if the one-electron picture is valid, the fully doped black sodalite is a narrow-band metal. The threshold in the spectrum appears because the transition matrix... [ABSTRACT FROM AUTHOR]

Abstract: The nanoscale integration of copper metal, frequently with semiconductor heterostructure interfaces, is a promising route for fabricating new micro‐/nanoelectronic devices. Synthesizing such systems using wet‐chemistry methods requires stabilization of nano‐Cu against corrosion/oxidation, which has proven to be challenging. Here we report a methodology for the facile preparation of Cu@TiO2 core‐shell nanowires (NWs). The synthesis combines redox formation of Cu NWs with kinetically controlled hydrolysis of a titania precursor in a single‐pot microwave reaction. The final core‐shell NWs can be precisely tailored with 20‐nm to 140‐nm Cu core diameters, aspect ratios >250, and a 10‐nm porous titania shell. This metal/semiconductor heterojunction is particularly important for its excellent photocatalytic activity. The rapid microwave‐assisted synthesis provides a potentially generalizable paradigm for the rational design of heterogeneous nanostructures with metals and oxides. [ABSTRACT FROM AUTHOR]

© 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A large (40 mm Φ) composite membrane with mesoporous silica nanotubes (F127MST) was coated with a thin carbon layer (1–2 graphene sheets) by carrying out chemical vapor deposition (CVD) using acetylene, and the obtained carbon-coated F127MST (C/F127MST) was used directly as an electrode. After evaluating the electrical conductivity inside the continuous mesopore network, the enzyme bilirubin oxidase (BOD) was loaded into the mesopores of C/F127MST to form BOD–C/F127MST. Indeed, this loading procedure was effective and achieved direct electron transfer between the enzymes and electrodes. The loading also was found to enhance the stability of stored BOD (it was stable for 15 days) and could be used to control the enzymatic reaction by varying the electric potential. We therefore consider BOD–C/F127MST to be a promising candidate as an effective bioelectrode in various fields. [ABSTRACT FROM AUTHOR]

We present a sensitive and quantitative protein detection assay that can efficiently distinguish between specific and nonspecific target binding. Our technique combines dual affinity reagents with surface-enhanced Raman spectroscopy (SERS) and chemometric analysis. We link one Raman reporter-tagged affinity reagent to gold nanoparticles and another to a gold film, such that protein-binding events create a “hot spot” with strong SERS spectra from both Raman reporter molecules. Any signal generated in this context is indicative of recognition by both affinity labels, whereas signals generated by nonspecific binding lack one or the other label, enabling us to efficiently distinguish true from false positives. We show that the number of hot spots per unit area of our substrate offers a quantitative measure of analyte concentration and demonstrate that this dual-label, SERS-linked aptasensor assay can sensitively and selectively detect human α-thrombin in 1% human serum with a limit of detection of 86 pM. [ABSTRACT FROM AUTHOR]

Janus nanoparticles (JNPs) offer unique features, including the precisely controlled distribution of compositions, surface charges, dipole moments, modular and combined functionalities, which enable excellent applications that are unavailable to their symmetrical counterparts. Assemblies of NPs exhibit coupled optical, electronic and magnetic properties that are different from single NPs. Herein, we report a new class of double-layered plasmonic-magnetic vesicle assembled from Janus amphiphilic Au-Fe3O4 NPs grafted with polymer brushes of different hydrophilicity on Au and Fe3O4 surfaces separately. Like liposomes, the vesicle shell is composed of two layers of Au-Fe3O4 NPs in opposite direction, and the orientation of Au or Fe3O4 in the shell can be well controlled by exploiting the amphiphilic property of the two types of polymers. [ABSTRACT FROM AUTHOR]

Janus nanoparticles (JNPs) offer unique features, including the precisely controlled distribution of compositions, surface charges, dipole moments, modular and combined functionalities, which enable excellent applications that are unavailable to their symmetrical counterparts. Assemblies of NPs exhibit coupled optical, electronic and magnetic properties that are different from single NPs. Herein, we report a new class of double-layered plasmonic-magnetic vesicle assembled from Janus amphiphilic Au-Fe3O4 NPs grafted with polymer brushes of different hydrophilicity on Au and Fe3O4 surfaces separately. Like liposomes, the vesicle shell is composed of two layers of Au-Fe3O4 NPs in opposite direction, and the orientation of Au or Fe3O4 in the shell can be well controlled by exploiting the amphiphilic property of the two types of polymers. [ABSTRACT FROM AUTHOR]

AgPd alloy nanoparticles deposited on carbon nitride have been synthesized by a facile one-step reduction method and exhibit high catalytic activity at near room temperature (30 °C) for formic acid dehydrogenation, both under visible light and in darkness. The study proves that using the synergistic combination of alloying effects and metal-support interactions greatly enhances the catalytic activity of Pd-based nanocatalysts for hydrogen generation. [ABSTRACT FROM AUTHOR]

A general, substrate-independent method for plasma deposition of nanostructured, crystalline metal oxides is presented. The technique uses a flow-through, micro-hollow cathode plasma discharge (supersonic microplasma jet) with a "remote" ring anode to deliver a highly directed flux of growth species to the substrate. A diverse range of nanostructured materials (e.g., CuO, α-Fe2O3, and NiO) can be deposited on any room temperature surface, e.g., conductors, insulators, plastics, fibers, and patterned surfaces, in a conformal fashion. The effects of deposition conditions, substrate type, and patterning on film morphology, nanostructure, and surface coverage are highlighted. The synthesis approach presented herein provides a general and tunable method to deposit a variety of functional and hierarchical metal oxide materials on many different surfaces. High surface area, conversiontype CuO electrodes for Li-ion batteries are demonstrated as a proof-of-concept example. [ABSTRACT FROM AUTHOR]

We report utilization of graphitic carbon nitride (g-CN) as an electrocatalyst for dye-sensitized solar cells (DSSCs). Crystalline poly(triazine imide) based g-CN was synthesized via a modified ionothermal method, and deposited onto the counter electrodes along with a conductive additive and a sacrificial polymer binder. The resulting DSSCs exhibited a power conversion efficiency (7.8%) comparable to that of conventional Pt catalyst (7.9%), confirming the excellent catalytic activity of poly(triazine imide) g-CN as a non-precious metal electrocatalyst. [ABSTRACT FROM AUTHOR]

A high-yielding synthesis of a series of polyimide dendrimers, including decacyclene- and perylene-containing dendrimer D6, in which two types of polyimide dyes are present, is reported. In these constructs, the branching unit is represented by trisphenylamine, and the solubilizing chains by N-9-heptadecanyl-substituted perylene diimides. The photophysical properties of the dendrimers have been studied by absorption, steady-state, and time-resolved emission spectroscopy and pump-probe transient absorption spectroscopy. Photoinduced charge-separated (CS) states are formed on the femtosecond timescale upon visible excitation. In particular, in D6, two different CS states can be formed, involving different subunits that decays independently with different lifetimes (ca. 10-100 ps). [ABSTRACT FROM AUTHOR]

A high-yielding synthesis of a series of polyimide dendrimers, including decacyclene- and perylene-containing dendrimer D6, in which two types of polyimide dyes are present, is reported. In these constructs, the branching unit is represented by trisphenylamine, and the solubilizing chains by N-9-heptadecanyl-substituted perylene diimides. The photophysical properties of the dendrimers have been studied by absorption, steady-state, and time-resolved emission spectroscopy and pump-probe transient absorption spectroscopy. Photoinduced charge-separated (CS) states are formed on the femtosecond timescale upon visible excitation. In particular, in D6, two different CS states can be formed, involving different subunits that decays independently with different lifetimes (ca. 10-100 ps). [ABSTRACT FROM AUTHOR]

Plasmonic nanosystems have recently been shown to be capable of functioning as photovoltaics and of carrying out redox photochemistry, purportedly using the energetic electrons and holes created following plasmonic decay as charge carriers. Although such devices currently have low efficiency, they already manifest a number of favorable characteristics, such as their tunability over the entire solar spectrum and a remarkable resistance to photocorrosion. Here, we report a plasmonic photovoltaic using a 25 μm thick electrolytic liquid junction which supports the iodide/triiodide (I−/I3−) redox couple. The device produces photocurrent densities in excess of 40 μA cm−2, an open circuit voltage (Voc) of ∼0.24 V and a fill factor of ∼0.5 using AM 1.5 G solar radiation at 100 mW cm−2. The photocurrent and the power conversion efficiency are primarily limited by the low light absorption in the 2-D gold nanoparticle arrays. The use of a liquid junction greatly reduces dielectric breakdown in the oxide layers utilized, which must be very thin for optimal performance, leading to a great improvement in the long-term stability of the cell's performance. [ABSTRACT FROM AUTHOR]

We present a silica nanoparticle (SNP) functionalized with polyphosphate (polyP) that accelerates the natural clotting process of the body. SNPs initiate the contact pathway of the blood-clotting system; short-chain polyP accelerates the common pathway by the rapid formation of thrombin, which enhances the overall blood-clotting system, both by accelerating fibrin generation and by facilitating the regulatory anticoagulation mechanisms essential for hemostasis. Analysis of the clotting properties of bare SNPs, bare polyP, and polyP-functionalized SNPs in plasma demonstrated that the attachment of polyP to SNPs to form polyP-SNPs creates a substantially enhanced synergistic effect that lowers clotting time and increases thrombin production at low concentrations. PolyP-SNP even retains its clotting function at ambient temperature. The polyP-SNP system has the potential to significantly improve trauma-treatment protocols and outcomes in hospital and prehospital settings. [ABSTRACT FROM AUTHOR]

We present a silica nanoparticle (SNP) functionalized with polyphosphate (polyP) that accelerates the natural clotting process of the body. SNPs initiate the contact pathway of the blood-clotting system; short-chain polyP accelerates the common pathway by the rapid formation of thrombin, which enhances the overall blood-clotting system, both by accelerating fibrin generation and by facilitating the regulatory anticoagulation mechanisms essential for hemostasis. Analysis of the clotting properties of bare SNPs, bare polyP, and polyP-functionalized SNPs in plasma demonstrated that the attachment of polyP to SNPs to form polyP-SNPs creates a substantially enhanced synergistic effect that lowers clotting time and increases thrombin production at low concentrations. PolyP-SNP even retains its clotting function at ambient temperature. The polyP-SNP system has the potential to significantly improve trauma-treatment protocols and outcomes in hospital and prehospital settings. [ABSTRACT FROM AUTHOR]

An acetylcholinesterase-immobilized sensor unit was successfully prepared by encapsulating the enzyme within hybrid mesoporous silica membranes (F127-MST). Through a novel combination with tetracyanoquinodimethane, both acetylcholine and organophosphorus pesticides were successfully detected with high sensitivity. Furthermore, we manufactured the working prototype of an enzyme sensor with this sensor unit for detecting dichlorvos, aldicarb and parathion. At present, the detection limit in this working prototype either equaled or surpassed that of others. Also, we have the advantage of increased stability of the enzyme against the outer environment by encapsulation of the enzymes into a silica nanospace. Consequently, acetylcholinesterase immobilized in F127-MST is a practical sensor with high sensitivity, reusability, and storage stability. [ABSTRACT FROM AUTHOR]

The thermoelectric properties of the Magnéli phase WO2.90 were investigated, with special attention to how the thermoelectric performance can be altered by changing its microstructure. Spark plasma sintering (SPS) allowed the direct preparation of large amounts of consolidated material. Adding Ta2O5 to the reaction mixture lead to the formation of solid solutions W1 -- xTaxO2.90 via a concurrent reaction between WO3 and Ta2O5 during the SPS treatment. In addition, micron-sized inclusions containing tungsten surrounded by WOx embedded in a WO2.90 matrix were formed, which act as additional scattering centers. As a result, the thermal conductivity of the Ta-containing samples was reduced by ≈ 30% over the temperature range from 300 to 1100 K while the electronic properties remained unaffected, which in turn enhanced the thermoelectric performance and led to a relatively high zT value of 0.15 at 1100 K for n-type metal oxides. [ABSTRACT FROM AUTHOR]

Because of microbial resistance to conventional antibiotics, there is increasing interest in silver, including silver nanoparticles (nano-Ag), in antimicrobial applications. However, questions remain regarding the relative roles of nano-Ag particles, versus Ag+ ions released from nano-Ag dissolution, in imparting bacterial toxicity. Here, we developed a novel nano-Ag that, based on its cysteine cap, was expected to dissolve slowly and thus potentially allow for differentiating nanoparticle, versus ionic, effects of Ag. The nano-Ag was systematically tested for its differential toxicity to Escherichia coli and Pseudomonas aeruginosa. Bacterial growth, reactive oxygen species (ROS) generation, particle dissolution, cellular electron transfer activity, and cell membrane damage and potential were evaluated. In minimal growth medium, E. coli and P. aeruginosa growth were slowed at 100 mg L−1 (0.93 mM) and 5 mg L−1 (0.046 mM), respectively; P. aeruginosa was completely inhibited at and above 10 mg L−1 (0.093 mM). For both strains, toxicity was associated with ROS and cell membrane damage. Based on comparisons to AgNO3 exposures, toxicity from nano-Ag was due to Ag+ ions and not intact nano-Ag, even though nanoparticle dissolution was less than 2% in minimal growth medium. Because of their stability and slow Ag+ ion release, the cysteine-capped nano-Ag particles here are useful to antimicrobial applications. Additionally, our systematic approach to evaluating toxicity, membrane damage, and ROS generation can be applied with other nanomaterials and bacteria. [ABSTRACT FROM AUTHOR]

Nitrogen-rich carbon microporous spheres (NCMSs) are synthesized for the first time by carbonizing melamine-formaldehyde spheres (MFSs). The surface area of NCMSs is increased approximately 100 times after the carbonization process. The NCMS synthetic process is facile and convenient to reproduce since the hard template production step is eliminated. In addition, the 13C MAS NMR spectrum for the NCMSs shows that the spheres are consisting of carbon atoms with multiple sp2 bonding configurations. Moreover, we find that nanopores in NCMSs offer high uptake capacity for hydrogen molecules. [ABSTRACT FROM AUTHOR]

We present a rapid microwave-assisted sol-gel approach to Pd-substituted LnFeO3 (Ln = Y, La) for applications in C-C coupling reactions. These materials could be prepared in household microwave ovens in less than 15 minutes of reaction time with the final materials displaying well-defined structure and morphology. Phase evolution was studied using time-dependent microwave heatings and then compared with the results obtained from thermogravimetric analyses. Materials were confirmed to be phase pure by laboratory and synchrotron X-ray diffraction. Substituted Pd is ionic as shown by the binding energy shift from X-ray photoelectron spectroscopy. The short heating periods required for phase purity allow these materials less time for sintering as compared to conventional solid state preparation methods, making relatively high surface areas achievable. These materials have been successfully used as catalyst precursor materials for C-C coupling reactions in which the active species is Pd0. Pd-substituted LnFeO3 (Ln = Y, La) provides Pd0 in solution which can be complexed by the ligand SPhos, allowing for aryl chloride coupling. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-CN) is a promising heterogeneous metal-free catalyst for organic photosynthesis, solar energy conversion, and photodegradation of pollutants. Its catalytic performance is easily adjustable by modifying texture, optical, and electronic properties via nanocasting, doping, and copolymerization. However, simultaneous optimization has yet to be achieved. Here, a facile synthesis of mesoporous g-CN using molecular cooperative assembly between triazine molecules is reported. Flower-like, layered spherical aggregates of melamine cyanuric acid complex (MCA) are formed by precipitation from equimolecular mixtures in dimethyl sulfoxide (DMSO). Thermal polycondensation of MCA under nitrogen at 550 °C produces mesoporous hollow spheres comprised of tri- s-triazine based g-CN nanosheets (MCA-CN) with the composition of C3N4.14H1.98. The layered structure succeeded from MCA induces stronger optical absorption, widens the bandgap by 0.16 eV, and increases the lifetime of photoexcited charge carriers by twice compared to that of the bulk g-CN, while the chemical structure remains similar to that of the bulk g-CN. As a result of these simultaneous modifications, the photodegradation kinetics of rhodamine B on the catalyst surface can be improved by 10 times. [ABSTRACT FROM AUTHOR]

We describe the preparation and simultaneous consolidation of WO2.90 by spark plasma sintering (SPS). SPS allows for the direct manufacturing of large amounts of consolidated material. Synchrotron powder X-ray diffraction indicates that the material is single phase. Microstructure analysis indicates that the pellet is fully dense, allowing high-temperature thermoelectric properties to be reliably measured. The as-prepared samples of WO2.90 reach a ZT of 0.1 at 1100 K. [ABSTRACT FROM AUTHOR]

Einfache kooperative Zusammenlagerung organischer Triazinmoleküle führt zu dreidimensionalen makroskopischen Aggregaten aus niederdimensionalen graphitischen Kohlenstoffnitriden in Form von Nanopartikeln, ‐ röhren und ‐ blättern. Kooperative Eigenschaften und photokatalytische Aktivitäten dieser Materialien in der Wasserstoffentwicklung aus Wasser unter Bestrahlung mit sichtbarem Licht wurden charakterisiert. [ABSTRACT FROM AUTHOR]

Simple organic cooperative assembly of triazine molecules leads to three‐dimensional macroscopic assemblies of low‐dimensional graphitic carbon nitrides (g‐CNs), for example, nanoparticles, nanotubes, and nanosheets. The approach enables the characterization of the cooperative properties and photocatalytic activities of low‐dimensional g‐CN materials in hydrogen evolution reactions from water under visible light. [ABSTRACT FROM AUTHOR]

Delafossite CuCrO2 and spinel CuCr2O4 with mesoporous structures have been successfully synthesized using nanocasting methods based on a KIT-6 template. The functional activity of the mesoporous materials was evaluated in applications as heterogeneous catalysts. The activity for photocatalytic hydrogen production of the delafossite structures with different morphologies was characterized and the oxidation state changes associated with photocorrosion of Cu+ investigated using electron energy loss spectroscopy (EELS). Mg2+ doping was found to facilitate the casting of ordered structures for CuCrO2 and improves the photocorrosion resistance of delafossite structures. The mesoporous spinel CuCr2O4 nanostructures were found to be active for low temperature CO oxidation. [ABSTRACT FROM AUTHOR]

Highly ordered mesoporous crystalline MoSe2 is synthesized using mesoporous silica SBA-15 as a hard template via a nanocasting strategy. Selenium powder and phosphomolybdic acid (H3PMo12O40) are used as Se and Mo sources, respectively. The obtained products have a highly ordered hexagonal mesostructure and a rod-like particle morphology, analogous to the mother template SBA-15. The UV-vis-NIR spectrum of the material shows a strong light absorption throughout the entire visible wavelength region. The direct bandgap is estimated to be 1.37 eV. The high surface area MoSe2 mesostructure shows remarkable photocatalytic activity for the degradation of rhodamine B, a model organic dye, in aqueous solution under visible light irradiation. In addition, the synthesized mesoporous MoSe2 possess a reversible lithium storage capacity of 630 mAh g−1 for at least 35 cycles without any notable decrease. The rate performance of mesoporous MoSe2 is much better than that of analogously synthesized mesoporous MoS2, making it a promising anode for the lithium ion battery. [ABSTRACT FROM AUTHOR]

Conversion reaction cells afford the ability to explore new energy storage paradigms that transcend the dogma of small, low-charge cations essential to intercalative processes. Here we report the use of earth-abundant and green calcium and sulfur in unprecedented conversion reaction Ca-S primary cells. Using S-infiltrated mesoporous carbon (abbreviated S@ meso-C) cathodes, we achieve discharge capacities as high as 600 mAh g−1 (S basis) within the geometry Ca|Ca(ClO4)2/CH3CN|S@ meso-C, at a discharge rate of C/3.5. The electrolyte system in the Ca-S battery is of paramount importance as the solid electrolyte interface (SEI) formed on the Ca anode limits the capacity and stability of the cell. We determine that 0.5 M Ca(ClO4)2 in CH3CN forms an SEI that advantageously breaks down under anodic bias to allow oxidation of the anode. This same SEI, however, exhibits high impedance which increases over time at open circuit limiting the shelf life of the cell. [ABSTRACT FROM AUTHOR]