The adsorption and dehydrogenation behaviors of ammonia on W(111) surface have been studied by employing spin-polarized density function theory calculations. In this work, three adsorption sites of the W(111) surface were considered, such as top (T), 3-fold-shallow (S), and 3-fold-deep (D) sites. The most stable structures of each NH x (x = 0−3) species on the W(111) surface have been predicted, and the corresponding dehydrogenation processes were found to be via two specific paths (A and B). In PATH A, the calculated activation energies for NH x (x = 1−3) dehydrogenations are 27.66 kcal/mol (for H 2 N−H bond activation), 32.66 kcal/mol (for HN−H bond activation) and 27.84 kcal/mol (for N−H bond activation), respectively, and the entire process is exothermic by 41.63 kcal/mol. On the other hand, in PATH B, the corresponding activation barriers are 35.97, 29.99, and 29.80 kcal/mol, respectively, and the entire process is 42.19 kcal/mol exothermic. To gain more insight into catalytic processes of the aforementioned conducts, the interaction nature between the adsorbate and substrate is analyzed via detailed electronic analysis.

We carried out a computational study of radical reactions of RNCN (R = H, F, Cl, Br, CH(3)) + NO to investigate how the substitution can influence their corresponding energy barriers and rate coefficients. The preferable reactive sites of RNCN radicals with various substituents are calculated by employing the Fukui functions and hard-and-soft acid-and-base theory, which were generally proved to be successful in the prediction and interpretation of regioselectivity in various types of electrophilic and nucleophilic reactions. Our calculated results clearly show that if the substituted RNCN radical has electron-donating substituent (for R = CH(3)), its corresponding barrier heights for transition states will be substantially decreased. The possible explanations of the observed increase and/or decrease in the energy barriers for the varied substituted RNCN radicals are also analyzed in this article.

We studied the mechanism of the water−gas shift reaction (WGSR; CO + H 2 O → CO 2 + H 2 ) catalyzed by Co 6 @Au 32 core−shell nanoalloy using density-functional theory (DFT) calculations to investigate the bimetallic effects on the catalytic activation. The molecular structures and adsorbate/substrate interaction energies were predicted, along with the potential energy surface constructed using the nudged elastic band (NEB) method. Our results indicated that the energetic barriers of the two hydrogen dissociation reactions are lower on the core−shell nanoalloy than on Au 38 . Furthermore, all of the related chemical species of the WGSR can adsorb stably on Co 6 @Au 32 to allow the reactions to take place under ambient pressure. To gain insight into the synergistic effect in the catalytic activity of the Co 6 @Au 32 nanoalloy, the nature of the interaction between the adsorbate and substrate was analyzed by detailed electronic local densities of states (LDOS) as well as molecular structures.