Theoretical study of the role of the interface of Ag4 nanoclusters deposited on TiO2(110) and TiO2(101).

SCHVVAL A. BELEN; JUAN ALFREDO; CABEZA GABRIELA. F.

APPLIED SURFACE SCIENCE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2019

0169-4332

Metal nanoclusters deposited on oxides as support play an important role for thedesign of catalysts model with applications in heterogeneous catalysis. In general, the oxidecontributes to stabilize the nanoparticles avoiding their sintering. Noble metals such as silver(Ag) supported on reducible oxides such as titania have been shown to be efficient for thereduction of harmful gases such as nitrogen oxides (NOx). In order to improve theperformance of the catalyst and the fundamental knowledge of the nature of the catalyticactivity, it was decided to study the titania as support for this system.From ab initio calculations using the Density Functional Theory (DFT + U), the energeticand structural properties of Ag4 clusters were studied in tetrahedral and planar configurationsdeposited on the stoichiometric surfaces of rutile TiO2(110) and anatase TiO2(101) tocharacterize the different aspects of the metal-oxide interaction that provide valuableinformation for future research. For both surfaces, we find that the tetrahedral configuration ispreferred, as experiments indicate.In all cases studied, the Ag nanoparticles are oxidized, yielding its electrons to thetitania. The highest net charge transfer occurs in the case of the rutile surface and is related tothe highest adsorption energies observed. However in the case of anatase surface a reversal inthe relationship is observed: higher charge transfer, lower adsorption energy.