Active sites and the catalytic mechanism of nitrogen-doped graphene in an oxygen reduction reaction (ORR) have been extensively studied but are still inconclusive, partly due to the lack of an experimental method that can detect the active sites. It is proposed in this report that the active sites on nitrogen-doped graphene can be determined via the examination of its chemical composition change before and after ORR. Synchrotron-based X-ray photoelectron spectroscopy analyses of three nitrogen-doped multilayer graphene samples reveal that oxygen reduction intermediate OH(ads), which should chemically attach to the active sites, remains on the carbon atoms neighboring pyridinic nitrogen after ORR. In addition, a high amount of the OH(ads) attachment after ORR corresponds to a high catalytic efficiency and vice versa. These pinpoint that the carbon atoms close to pyridinic nitrogen are the main active sites among the different nitrogen doping configurations.

Poly(triazine imide) with intercalation of lithium and chloride ions (PTI/Li(+)Cl(-)) was synthesized by temperature-induced condensation of dicyandiamide in a eutectic mixture of lithium chloride and potassium chloride as solvent. By using this ionothermal approach the well-known problem of insufficient crystallinity of carbon nitride (CN) condensation products could be overcome. The structural characterization of PTI/Li(+)Cl(-) resulted from a complementary approach using spectroscopic methods as well as different diffraction techniques. Due to the high crystallinity of PTI/Li(+)Cl(-) a structure solution from both powder X-ray and electron diffraction patterns using direct methods was possible; this yielded a triazine-based structure model, in contrast to the proposed fully condensed heptazine-based structure that has been reported recently. Further information from solid-state NMR and FTIR spectroscopy as well as high-resolution TEM investigations was used for Rietveld refinement with a goodness-of-fit (χ(2)) of 5.035 and wRp=0.05937. PTI/Li(+)Cl(-) (P6(3)cm (no. 185); a=846.82(10), c=675.02(9) pm) is a 2D network composed of essentially planar layers made up from imide-bridged triazine units. Voids in these layers are stacked upon each other forming channels running parallel to [001], filled with Li(+) and Cl(-) ions. The presence of salt ions in the nanocrystallites as well as the existence of sp(2)-hybridized carbon and nitrogen atoms typical of graphitic structures was confirmed by electron energy-loss spectroscopy (EELS) measurements. Solid-state NMR spectroscopy investigations using (15)N-labeled PTI/Li(+)Cl(-) proved the absence of heptazine building blocks and NH(2) groups and corroborated the highly condensed, triazine-based structure model.

Aluminum aminoterephthalate Al(OH)[H(2)N-BDC] x 0.3 (H(2)N-H(2)BDC (denoted MIL-53-NH(2)(as)) was synthesized under hydrothermal conditions. The activation of the compound can be achieved in two steps. The treatment with DMF at 150 degrees C leads to Al(OH)[H(2)N-BDC] x 0.95 DMF (MIL-53-NH(2)(DMF)). In the second step, DMF is thermally removed at 130 degrees C. Upon cooling in air, the hydrated form Al(OH)[H(2)N-BDC] x 0.9 H(2)O (MIL-53-NH(2)(lt)) is obtained. The dehydration leads to a porous compound that exhibits hysteresis behavior in the N(2) sorption experiments. The MIL-53-NH(2)(lt) can be modified by postsynthetic functionalization using formic acid, and the corresponding amide Al(OH)[HC(O)N(H)-BDC] x H(2)O (MIL-53-NHCHO) is formed. All four phases were thoroughly characterized by X-ray powder diffraction, solid-state NMR and IR spectroscopy, and sorption measurements, as well as thermogravimetric and elemental analysis. Based on the refined lattice parameter similar breathing behavior of the framework as found in the unfunctionalized MIL-53 can be deduced. Solid-state NMR spectra unequivocally demonstrate the presence of the guest species, as well as the successful postsynthetic functionalization.

ARTICLE This journal isWith the expected theoretical capacity of 2,596 mAh g -1 , phosphorus is considered to be the highest capacity anode material for sodium-ion batteries and one of the most attractive anode materials for lithium-ion systems. This work presents a comprehensive study of phosphoruscarbon nanocomposite anodes for both lithium-ion and sodium-ion batteries. The composite electrodes are able to display high initial capacities of approximately 1,700 and 1,300 mAh g -1 in lithium and sodium half-cells, respectively, when the cells are tested within a larger potential windows of 2.0 -0.01 V vs Li/Li + and Na/Na + . The level of demonstrated capacity is underpinned by the storage mechanism, based on the transformation of phosphorus to Li 3 P phase for lithium cells and an incomplete transformation to Na 3 P phase for sodium cells. The capacity deteriorates upon cycling, which is shown to originate from disintegration of electrodes and their delamination from current collectors by post-cycling ex-situ electron microscopy. Stable cyclic performance at the level of ~700 and ~350-400 mAh g -1 can be achieved if the potential windows are restricted to 2.0 -0.67 V vs Li/Li + for lithium and 2 -0.33 vs Na/Na + for sodium half-cells. The results are critically discussed in light of existing literature reports. Figure 4. TEM analysis of phosphorus and phosphorus-carbon samples . (a, b) Selected area electron diffraction patterns of the red and black phases of phosphorus (bright-field images are shown as insets); (c, d, e) an elastic image, carbon and phosphorus energy-filtered elemental maps of the composite C-1; (f, g, h) an elastic image, carbon and phosphorus energy-filtered elemental maps of the composite C-2 (colour scheme: green -carbon, red -phosporus).Phosphorus -carbon nanocomposites were systematically evaluated as high capacity anodes for both lithium-ion and sodium-ion batteries. The composites are able to provide attractive capacities based on alloying-dealloying operating mechanism but their cyclic performance depends significantly on the operating potential window; the capacity declines monotonously within the window of 2 -0.01 V vs Li/Li + or Na/Na + and is very stable in a narrower potential window.

Al together now! A new stable aluminum aminoterephthalate system contains octameric building blocks that are connected by organic linkers to form a 12-connected net (see picture). The structure adopts a cubic centered packing motive in which octameric units replace individual atoms, thus forming distorted octahedral (red sphere) and tetrahedral cages (green spheres) with effective accessible diameters of 1 and 0.45 nm, respectively.