Studies of hydrocarbon surface processes by the multipulse potentiodynamic method. Part 3.—Kinetics of adsorption of ethylene and acetylene on platinum and the structure of the adsorbed layer at low potentials

Abstract

A sequence of potential pulses may be used to effect the reproducible adsorption of ethylene or of acetylene from perchloric acid solution. During the course of adsorption (smooth platinum micro-electrode) at 0.4 V and 30°C, measurement was made of the charge corresponding to adsorbed hydrocarbon (through oxidation to CO₂ and H₂O), the charge corresponding to hydrogen co-deposition, and the current corresponding to hydrogen dissociated from ethylene. The results suggest similar compositions of the ad-layers (probably corresponding to the composition C₂H₂) for the two different adsorbates, under the specific conditions employed. The adsorption rate conforms well to a simple diffusion law, establishing the quantitative validity of the MPP measurement technique for these systems.