Surface fractal dimension of small metallic particles

Structural effects in the kinetic behavior of the monomer–dimer surface reaction over nondeterministic fractal surfaces

A study is made of the segregation effect of adsorbed species related to the inner structure of two bidimensional adsorbent fractals, the incipient percolation cluster (IPC) and the backbone of the IPC, and their connection with the rate-determining step of the kinetic mechanism of the monomer-dimer (MD) surface reaction on those fractals. Production, R(AB), is proportional to the concentration of A in the gas phase y(A) and to the fraction of vacant superficial sites x(E) (R(AB)=y(A)x(E)), and it is shown that adsorption of the monomer is the rate-controlling step of the reaction mechanism.

Fractal analysis of size effects and surface morphology effects in catalysis and electrocatalysis

Fractal geometry tools are used in order to analyze several related problems in surface science, catalysis, and electrocatalysis. The effects of complex morphologies of adsorbents, catalysts, and electrodes on various molecular processes with these materials are determined both theoretically and experimentally. It is shown that fractal geometry provides a convenient and natural tool for the elucidation of geometry-performance relations in heterogeneous chemistry. Issues covered are particle size effects in physisorption and chemisorption; morphology effects on a variety of catalytic processes with unsupported catalysts (including coal liquefaction, alkene polymerizations, oxidations, dehydrogenations, and esterifications); surface accessibility effects on molecular interactions in an Eley-Rideal mechanism; surface patterning effects on concentration profiles near the surface; and electrode-morphology effects on a variety of electrochemical and electrocatalytic processes. The domains of applicability of the fractal approach to these problems is discussed.