Heterolytic Adsorption of H2 on ZnO(101̄0) Surface: An ab initio SPC Cluster Model Study

Methanol formation by catalytic hydrogenation of CO2 on a nitrogen doped zinc oxide surface: an evaluative study on the mechanistic pathway by density functional theory

Computational evaluation of reaction pathway for simultaneous activation of CO₂ and water on N doped ZnO surface revealed carbamate mediated methanol formation.

Characterization of hydrogen dissociation over aluminium-doped zinc oxide using an efficient massively parallel framework for QM/MM calculations

A task-farm parallelization framework has been implemented in the ChemShell computational chemistry environment to provide a facility for parallelizing common chemical calculations, including finite-difference Hessian evaluation, the nudged elastic band method for reaction path optimization, and population-based methods for global optimization. The optimization methods are provided by a parallel interface to the DL-FIND optimization library. As ChemShell can already exploit parallel external programs for energy and gradient evaluations, the new methods result in a two-level approach to parallelization that gives significantly improved performance for massively parallel calculations. For typical systems, speed-up factors of five to eight times have been observed compared with non-task-farmed calculations. The task-farming version of ChemShell has been used to study the heterolytic dissociation of a hydrogen molecule over a polar oxygen-terminated surface of aluminium-doped zinc oxide using an embedded cluster hybrid QM/MM approach. We calculate a 42 kcal mol −1 heat of reaction and a 30 kcal mol −1 activation energy, which is equivalent to a high backward reaction barrier of 72 kcal mol −1 per H 2 molecule, in close agreement with temperature programmed desorption experiments. The dissociation path includes a stable intermediate comprising a hydride ion in an oxygen vacancy and physisorbed atomic hydrogen.

The identification of hydroxyl groups on ZnO nanoparticles by infrared spectroscopy

The interaction of water with ZnO nanoparticles has been studied by means of diffuse reflectance infrared spectroscopy (DRIFTS) and ultra-high vacuum FTIR spectroscopy (UHV-FTIRS). Exposing clean ZnO powder to water at 323 K leads to both molecular and dissociative adsorption of H2O forming a number of hydroxyl species. All the OH bands are clearly identified by the adsorption of D2O showing the expected isotopic shifts. According to the vibrational and thermal stability data obtained from single crystal surfaces, the OH species observed on ZnO nanoparticles are identified as follows: (1) OH group (3620 cm(-1)) on the polar O-ZnO(0001[combining macron]) surface formed via dissociation of water on oxygen vacancy sites; (2) partial dissociation of water on the mixed-terminated ZnO(101[combining macron]0) surface yielding coexistent H2O ( approximately 3150 and 3687 cm(-1)) and OH species (3672 cm(-1)), where the molecularly adsorbed H2O is further identified by the characteristic scissoring mode at 1617 cm(-1); (3) isolated OH species (3639 and 3656 cm(-1)) formed on the mixed-terminated ZnO(101[combining macron]0) surface; (4) interaction of water with defects forming hydroxyl (or O-HO) species (3564 and 3448 cm(-1)).