Kinetics of dissociative adsorption of formaldehyde on a Pt(111) electrode in sulphuric acid solutions studied using a programmed potential step technique and time-resolved Fourier transform IR spectroscopy

Abstract

The kinetics of dissociative adsorption of formaldehyde on Pt(111) electrodes was investigated using a programmed potential step technique and in situ time-resolved Fourier transform IR spectroscopy (TR-FTIRS). We have demonstrated that the products of dissociative adsorption of HCHO on Pt(111) consist of both linear and bridge bonded CO. In contrast, the adsorption of CO from CO saturated solution yields only linearly adsorbed CO species on this electrode. In the potential range between −0.25 and 0.25 V the rate of dissociative adsorption of HCHO on Pt(111) displays a volcano curve with two maxima located at −0.06 and 0.15 V respectively. The reaction rate maintains relatively high values between the two maxima. However, at potentials below −0.06 or above 0.15 V, the rate drops quickly towards zero. The initial rate ν i of the dissociative adsorption of HCHO on Pt(111) was found to be on the order of 10 −11 mol cm −2 s −1 . The TR-FTIRS studies confirmed the dynamic properties of the dissociative adsorption of HCHO on Pt(111) electrodes.