Fe2O3 Embedded in N-Doped Porous Carbon Derived from Hemin Loaded on Active Carbon for Supercapacitors.

The high power density and long cyclic stability of N-doped carbon make it an attractive material for supercapacitor electrodes. Nevertheless, its low energy density limits its practical application. To solve the above issues, Fe2O3 embedded in N-doped porous carbon (Fe2O3/N-PC) was designed by pyrolyzing Hemin/activated carbon (Hemin/AC) composites. A porous structure allows rapid diffusion of electrons and ions during charge-discharge due to its large surface area and conductive channels. The redox reactions of Fe2O3 particles and N heteroatoms contribute to pseudocapacitance, which greatly enhances the supercapacitive performance. Fe2O3/N-PC showed a superior capacitance of 290.3 F g-1 at 1 A g-1 with 93.1% capacity retention after 10,000 charge-discharge cycles. Eventually, a high energy density of 37.6 Wh kg-1 at a power density of 1.6 kW kg-1 could be delivered with a solid symmetric device.

New Covalent Triazine Framework Rich in Nitrogen and Oxygen as a Host Material for Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries have been widely considered as the next-generation energy storage system but hindered by the soluble polysulfide intermediate-induced shuttle effect. Doping heteroatoms was confirmed to enhance the affinity of polysulfide and the carbon host, release the shuttle effect, and improve the battery performance. To enhance the Lewis acidity and reinforce the interaction between polysulfide and the carbon skeleton, a novel covalent triazine framework (CTFO) was designed and fabricated by copolymerizing 2,4,6-triphenoxy-s-triazine and 2,4,6-trichloro-1,3,5-triazine through Friedel-Crafts alkylation. Polymerization led to triazine substitution on the para-position of the phenoxy groups of 2,4,6-triphenoxy-triazine and produced two-dimensional three-connected honeycomb nanosheets. These nanosheets were confirmed to exhibit packing in the AB style through the intralayer π-π interaction to form a three-dimensional layered network with micropores of 0.5 nm. The practical and simulated results manifested the enhanced polysulfide capture capability due to the abundant N and O heteroatoms in CTFO. The unique porous polar network endowed CTFO with improved Li-S battery performance with high Coulombic efficiency, rate capability, and cycling stability. The S@CTFO cathode delivered an initial discharge capacity of 791 mAh g-1 at 1C and retained a residual capacity of 512 mAh g-1 after 300 charge-discharge cycles with an attenuation rate of 0.117%. The present results confirmed that multiple heteroatom doping enhances the interaction between the porous polar CTF skeleton and polysulfide intermediates to improve the Li-S battery performance.

Facile synthesis of Nafion-supported Pt nanoparticles with ultra-low loading as a high-performance electrocatalyst for hydrogen evolution reaction.

x%Pt-Naf-CV (Pt-Nafion-Cyclic Voltammetry) catalysts with homogeneously distributed platinum nanoparticles and ultra-low Pt loading are successfully synthesized by using a facile potential cycling approach. The as-synthesized 0.8%Pt-Naf-CV catalyst exhibits an enhanced electrocatalytic activity for hydrogen evolution reaction (HER) in 0.5 M H2SO4 solution, which obtains a low overpotential of 34 mV at 10 mA cm-2. The linear sweep voltammetry (LSV) curve of 0.8%Pt-Naf-CV catalyst is almost consistent with that of commercial Pt/C. However, the 0.8%Pt-Naf-CV catalyst displays a more excellent stability and durability in comparison with commercial Pt/C. Besides, the Pt loading of Pt/C (Pt-10 wt%) is about 10 times that of 0.8%Pt-Naf-CV catalyst. The improved electrocatalytic performances are derived from the synergistic effects of Pt and Nafion. The Nafion plays a significant role as a dispersant, carrier and structure directing agent on the morphology and size of the Pt catalyst. This result contributes a promising method to enhance the catalytic activity and reduce the amount of Pt.

Controllable fabrication of Pt nanocatalyst supported on N-doped carbon containing nickel nanoparticles for ethanol oxidation.

In this paper, platinum nanoparticles were deposited on a carbon carrier with the partly graphitized carbon and the highly dispersive carbon-coated nickel particles. An efficient electron transfer structure can be fabricated by controlling the contents of the deposited platinum. The high resolution transmission electron microscopy images of Pt2/Ni@CN-doped sample prove the electron transfer channel from Pt (1 1 1) crystal planes to graphite (1 0 0) or Ni (1 1 1) crystal planes due to these linked together crystal planes. The Pt3/Ni@CN-doped with low Pt contents cannot form the electron transfer structure and the Pt1/Ni@CN-doped with high Pt contents show an obvious aggregation of Pt nanoparticles. The electrochemical tests of all the catalysts show that the Pt2/Ni@CN-doped sample presents the highest catalytic activity, the strongest CO tolerance and the best catalytic stability. The high performance is attributed to the efficient electronic transport structure of the Pt2/Ni@CN-doped sample and the synergistic effect between Pt and Ni nanoparticles. This paper provides a promising method for enhancing the conductivity of electrode material.

Self-supported fibrous porous aromatic membranes for efficient CO2/N2 separations.

In this paper, we describe a new synthesis protocol for the preparation of self-supported hollow fiber membranes composed of porous aromatic framework PAF-56P and PSF. PAF-56P was facilely prepared by the cross-coupling reaction of triangle-shaped cyanuric chloride and linear p-terophenyl monomers. The prepared PAF-56P material possesses an extended conjugated network, the structure of which is confirmed by nuclear magnetic resonance and infrared characterizations, as well as a permanent porosity with a BET surface area of 553.4 m(2) g(-1) and a pore size of 1.2 nm. PAF-56P was subsequently integrated with PSF matrix into PAF-56P/PSF asymmetric hollow fiber membranes via the dry jet-wet quench method employing PAF-56P/PSF suspensions. Scanning electron microscopy studies show that PAF-56P particles are embedded in the PSF matrix to form continuous membranes. Fabricated PAF-56P/PSF membranes were further exploited for CO2 capture, which was exemplified by gas separations of CO2/N2 mixtures. The PAF-56P/PSF membranes show a high selectivity of CO2 over N2 with a separation factor of 38.9 due to the abundant nitrogen groups in the PAF-56P framework. A preferred permeance for CO2 in the binary CO2/N2 gas mixture is obtained in the range of 93-141 GPU due to the large CO2 adsorption capacity and a large pore size of PAF-56P. Additionally, PAF-56P/PSF membranes exhibit excellent thermal and mechanical stabilities, which were examined by thermal analysis and gas separation tests with the dependencies of temperatures and pressures. The merits of high selectivity for CO2, good stability, and easy scale up make PAF-56P/PSF hollow fiber membranes of great interest for the industrial separations of CO2 from the gas exhausts.

The crystallinity effect of mesocrystalline BaZrO3 hollow nanospheres on charge separation for photocatalysis.

Highly crystalline mesocrystalline BaZrO3 hollow nanospheres offered higher photocatalytic activities. It is found that the highly crystalline sample can function as a "highway" for electron transport with less grain boundaries, resulting in better charge separation and thus photocatalytic performance.

Controllable synthesis and photoluminescence of single-crystalline BaHfO3 hollow micro- and nanospheres.

This paper presents a facile hydrothermal route to synthesize monodispersive and single-crystalline BaHfO(3) hollow micro- and nanospheres in a concentrated basic environment. The hollow spheres were size tunable from submicrometer to nanoscale by simply adjusting the base concentration at a suitable temperature. The base concentration played the key role on forming BaHfO(3) hollow spheres. Detailed investigations on base concentration, reaction temperature, and duration indicated that the formation of BaHfO(3) hollow spheres was driven by Ostwald ripening process. Because of the abundance of defects, the as-prepared BaHfO(3) hollow nanospheres exhibited a blue light emission under UV-light excitation at room temperature. Calcination led to the photoluminescence declination due to the decrease of defects.

Rationally fabricating hollow particles of complex oxides by a templateless hydrothermal route: the case of single-crystalline SrHfO3 hollow cuboidal nanoshells.

Based on the theory of sol-gel science, perovskite SrHfO(3) hollow cuboidal particles with tunable sizes were rationally synthesized by templateless hydrothermal reactions in KOH solutions. The concentrated KOH solution not only elevated the supersaturation of the reactants to promote the grain growth of SrHfO(3) but also controlled the aggregated particle sizes by compressing the electrical double layers of the primary particulates. The following Ostwald ripening process produced hollow particles with sizes ranging from submicrometer to hundred nanometre. The HRTEM image and SAED pattern revealed the single crystal nature of each hollow cuboidal nanoshell. The KOH concentration and reaction time related experiments confirmed that the formation of SrHfO(3) hollow cuboidal nanoshell was driven by the Ostwald ripening process and followed our assumption. The particles experienced solid, core-shell and hollow morphologies as the reaction proceeded. Also, the formation of SrHfO(3) hollow cuboidal nanoshells favored high reaction temperature which initiated and accelerated the ripening process. The as-prepared hollow cuboidal nanoshells displayed blue light emission under UV laser excitation at room temperature. After calcination, the photoluminescence intensity declined due to the improvement of crystallinity.

4,4'-Bipyridine-3-nitro-benzoic acid (1/2).

The title compound, C(10)H(8)N(2)·2C(7)H(5)NO(4),was obtained unintentionally as the harvested product of the hydro-thermal reaction between Co(OAc)(2)·4H(2)O and 4,4'-bipyridine in the presence of 3-nitro-phthalic acid. In the reaction, 3-nitro-phthalic acid is transformed into 3-nitro-benzoic acid by an in situ deca-rboxylation reaction, in which the carboxyl-ate group is not deprotonated and is uncoordinated. In the crystal, the uncoordinated 3-nitro-benzoic acid and free 4,4'-bipyridine mol-ecules are linked alternately by O-H⋯N hydrogen bonds into chains, which are assembled by C-H⋯O hydrogen bonds into a three-dimensional supra-molecular network.

Poly[[di-mu-aqua-tetraaquadi-mu-hydroxido-bis(mu3-3-nitrophthalato)tricopper(II)] dihydrate].

The novel title complex, {[Cu(3)(C(8)H(3)NO(6))(2)(OH)(2)(H(2)O)(6)].2H(2)O}(n), has a one-dimensional polymeric double chain structure where the three Cu atoms are linked by mu(2)-OH and mu(2)-H(2)O groups, and these trinuclear centres are bridged by two 3-nitrophthalate ligands. The asymmetric unit contains one and a half crystallographically independent Cu atoms (one lying on a centre of inversion), both coordinated by six O atoms and exhibiting distorted octahedral coordination geometries, but with different coordination environments. Each 3-nitrophthalate ligand connects to three Cu atoms through two O atoms of one carboxylate group and one O atom of the nitro group. The remaining carboxylate group is free and is involved in intrachain hydrogen bonds, reinforcing the chain linkage.

Doping-induced structure variation of 1,3-cyclohexane- bis(methylamine)-templated zinc-phosphorus open structures.

By using 1,3-cyclohexane-bis(methylamine) (CHBMA) as the template, a novel zinc phosphatophosphite (TJPU-3) with extra-large 20-ring channels was synthesized. Cobalt doping produced a bimetallic phosphite (TJPU-6) with 12-ring apertures. While the templates sit in the cis configuration in TJPU-3, they are in the trans configuration in TJPU-6. This result has the potential for separation and recognition of CHBMA isomers.