Hongqi Ye

Free-standing nitrogen-doped graphene paper as electrodes for high-performance lithium/dissolved polysulfide batteries.

Free-standing N-doped graphene papers (NGP), generated by pyrolysis of polydiallyldimethylammonium chloride, were successfully used as binder-free electrodes for the state-of-the-art Li/polysulfide-catholyte batteries. They exhibited high specific capacities of approximately 1000 mA h g(-1) (based on S) after 100 cycles and coulombic efficiencies great than 98%, significantly better than undoped graphene paper (GP). These NGP were characterized with XRD, X-ray photoelectron spectroscopy, thermogravimetric analysis, AFM, electron microscopy, and Raman and impedance spectroscopy before and after cycling. Spectroscopic evidence suggested stronger binding of sulfide to NGP relative to GP, and modelling results from DFT calculation, substantiated with experimental data, indicated that pyrrolic and pyridinic N atoms interacted more strongly with Li polysulfides than quaternary N atoms. Thus, more favorable partition of polysulfides between the electrode and the electrolyte and the corresponding effect on the morphology of the passivation layer were the causes of the beneficial effect of N doping.

G-C3N4-coated activated carbon-supported Pd catalysts for 4-CBA hydrogenation: effect of nitrogen species

We report here a g-C3N4-coated activated carbon as the support for Pd catalysts and investigate the effect of nitrogen species in g-C3N4 on the dispersity and stability of Pd.

A highly stable and active Pd catalyst on monolithic cordierite with graphene coating assisted by PDDA

A Pd catalyst on monolithic cordierite with graphene coating was prepared with assistance from poly(diallyldimethylammonium chloride) (PDDA). The obtained catalyst exhibits both high stability and activity in the liquid hydrogenation reaction of styrene due to the improved interaction between the graphene coating and cordierite and enhanced dispersion of Pd particles.

Effect of the replacement of Al–O by Si–N on the properties of Sr6Si25.6Al6.4N41.6O4.4:Eu2+ phosphors for white light-emitting diodes

Oxynitride phosphors Sr6Si25.6−xAl6.4+xN41.6−xO4.4+x:Eu2+ are synthesized by gas pressure sintering of powder mixture of SrCO3, AlN, Si3N4 and Eu2O3 at 1800 °C and 0.5 MPa of N2 for 10 h, and their photoluminescence properties are investigated. Sr6Si25.6−xAl6.4+xN41.6−xO4.4+x:Eu2+ can be efficiently excited over a broad spectral range between 300 and 500 nm, and exhibit an intense green emission centered at about 515 nm with a full width at half maximum of 65 nm due to the 4f65d1–4f7 transition of Eu2+ ions. The influence of the replacement of Si–N by Al–O on luminescence properties and crystal structure is reported in a series of Sr6Si25.6−xAl6.4+xN41.6−xO4.4+x:Eu2+ phosphors. Different Sr sites are found in the crystal structure. The thermal quenching properties of the green phosphors are better than that of typical orthosilicate Ba2SiO4:Eu2+ phosphor. Their interesting photoluminescence properties indicate that the Sr6Si25.6Al6.4N41.6O4.4 phosphor is a promising green emitting candidate for white LEDs applications.

Pd confined in grass-like graphene layers on monolithic cordierite as the catalyst for hydrogenation of 4-carboxybenzaldehyde

Pd nanoparticles were confined in grass-like graphene layers on monolithic cordierite by using nh2-ion liquid c(7)h(14)cln(3)functionalized graphene sheets. these were used as the catalyst for the hydrogenation of 4-carboxybenzaldehyde. the catalyst exhibited high stability compared to pd/activated carbon catalyst due to the inhibition of pd leaching and aggregation. (c) 2015, dalian institute of chemical physics, chinese academy of sciences. published by elsevier b.v. all rights reserved.