from first principles PP-I-1

OP-I-6Self-Induced Electric Fields in the System of Supported MetalNanoparticles: The Impact on Heterogeneous CatalysisGurevich S.A. 1 , Kozhevin V.M. 1 , Yavsin D.A. 1 , Rostovshchikova T.N. 2 , Lokteva E.S. 21 Ioffe Physical-Technical Institute of RAS, St. Petersburg, Russia2 Lomonosov Moscow State University, Moscow, Russiagurevich@quantel.ioffe.ruExternal electric fields are known to affect the catalytic processes [1]. In general, applicationof the electric field can result in significant enhancement of the catalytic reaction rate if thefield intensity is high enough, comparable with intramolecular fields. In practice, however,application of such strong field may cause undesirable heating or even breakdown of thereaction area. In case of heterogeneous catalysis the reasonable solution would beconcentration of strong electric field in close vicinity of the catalyst surface.In a system of supported metal nanoparticles, electrons can jump between the neighboringparticles or between the particles conducting support giving rise to the appearance of fastfluctuatingcharge dipoles [2]. Associated with such dipoles local electric fields may havepeak intensity up to 10 7 V/cm with life span in a wide range from 10 -8 s to 10 -13 s. Thesefields persist in rather small area, within particle-particle or particle-support gaps. For typicalsupported metal nanocatalysts the size of this area is still bigger than the size of reactingmolecules. This consideration suggests that the property of supported metal catalyst willessentially depend on the surface density of nanoparticles. One can expect such dependencebecause in a given system the particle density determines both the field strength and thepossibility for the reacting molecules to enter the field area.The experiments were performed with the catalysts comprising supported amorphous metalnanoparticles. Specific features of these particles are fixed size and enhanced coagulationstability which opens the possibility to thoroughly trace the catalytic activity against particledensity. At certain densities, when the field effects are expected to be most pronounced,unusually high catalytic activity was observed in different reactions with the use of differentmetals and corresponding supports. This clearly shows that the impact of self-induced electricfields on the properties of supported metal catalysts is very general phenomenon.This work was supported by RFBR (№ 10-03-00372, 11-03-00403).References:[1] P. Deshlahra, et.al., J. Phys. Chem. A, 113 (2009) 4125[2] S.A. Gurevich, et.al., Physico-Chemical Phenomena in Thin Films and at Solid Surfaces,L. I. Trakhtenberg, S. H. Lin, O. J. Ilegbusi, eds. Amsterdam: Elsevier 34 (2007) 72634