CO adsorption on a LaNi5 hydrogen storage alloy surface: a theoretical investigation.

Density functional theory calculations are carried out to study CO adsorption on the (001) surface of a LaNi(5) hydrogen storage alloy. At low coverages, CO favors adsorption on Ni-Ni bridge sites. With an increase in CO coverage, the decrease in the adsorption energy is much larger for Ni-Ni-CO bridge adsorption than that for Ni-CO on-top adsorption. Thus, the latter sites in the relatively stable adsorption structure are preferentially utilized at high CO coverages. The nature of the bonding between CO and the LaNi(5) (001) surface is analyzed in detail.

Dehydrogenation reaction for Na-O-H system: a first-principles study.

The crystal structures, electronic, dielectric, and vibrational properties of NaH, Na(2)O and NaOH are systematically investigated by first-principles calculations and the quasiharmonic approximation. The phonon dispersion relations and the phonon density of states of the phases and their thermodynamic functions including the heat capacity, the vibrational enthalpy, and the vibrational entropy are calculated using a direct force-constant method. Based on these results, the dehydrogenation reaction, NaH+NaOH-->H(2)+Na(2)O, is predicted to take place at 528 K, which is in agreement with the experimental observed value.

Tuning the formation of cadmium(II) urocanate frameworks by control of reaction conditions: crystal structure, properties, and theoretical investigation.

The reaction of cadmium(II) perchlorate with urocanic acid under different conditions created three novel coordination compounds: [Cd2(L2)2-(L3)2(H2O)8] (1), {[Cd(L)(L2)](H2O)(1/2)}n (2), and {[Cd(L3)2](H2O)(3/2)(EtOH)}n (3), in which L, L2, and L3 are three urocanate tautomers. Complex 1 consists of two separate mononuclear units with different urocanate tautomers, which self-assemble into a 3D hydrogen-bonding network constructed by alternating 2D layers, whereas complexes 2 and 3 self-assemble into 3D alpha-polonium and four-fold interpenetrated diamondoid networks, respectively. The tautomerism of the urocanate ligands and the enormous structural diversity of their complexes are present in this system, which illustrates that the reaction temperature, pressure, and the metal ions themselves act cooperatively to tune the tautomerism of the ligands and the frameworks of their metal coordination compounds. The fluorescence-emission and nitrogen-adsorption properties of these complexes are also investigated.