The Effect of Resorcinol on the Kinetics of Underpotentially Deposited Hydrogen and the Oxygen Evolution Reaction, Studied on Polycrystalline Pt in a 0.5 M H2SO4 Solution

Abstract

This article reports on the influence of resorcinol (RC) on the kinetics of underpotential deposition of hydrogen (UPD of H) and the oxygen evolution reaction (OER), studied on a polycrystalline Pt electrode in a 0.5 M sulphuric acid supporting solution. It is well known that both PEM fuel cells and water electrolysers’ electrodes often contain significant amounts of nanostructured Pt or other types of noble metal particles. These materials provide the superior catalytic activity of electrochemical reactions such as OER (oxygen evolution reaction), HER (hydrogen evolution reaction) and ORR (oxygen reduction reaction). The trace amounts of phenolic substances contained in air or water could be harmful (when in contact with a fuel cell/water electrolyser’s working environment) to the abovementioned catalytic surfaces. Hence, they could potentially have severe detrimental effects on the kinetics of these processes. The results obtained in this work provided evidence for the detrimental role of Pt surface-adsorbed resorcinol molecules (or their electrodegradation products) on the kinetics of UPD of H and the oxygen evolution reaction. The above was revealed through evaluation of the associated charge-transfer resistance and capacitance parameters, comparatively derived on a platinum electrode, for the initial and the resorcinol-modified H2SO4 electrolyte.

Electro-Reactivity of Resorcinol on Pt(111) Single-Crystal Plane and Its Influence on the Kinetics of Underpotentially Deposited Hydrogen and Hydrogen Evolution Reaction Processes in 0.1 M NaOH Solution

“…However, further laboratory work (perhaps with the involvement of additional, in-situ infrared experiments) would be required in order to provide detailed understanding of the process of RC-ion adsorption on the surface of Pt(111) plane and to provide more insights into competitive RC-ion-to-UPD of H adsorption, especially on how it might affect the kinetics and mechanisms of processes of UPD and OPD of H, and HER Faradaic reaction, also in relation to the behaviour recently reported in Ref. [8] for 0.5 M H 2 SO 4 .…”

“…Interestingly, in recent work from this laboratory [8], resorcinol has been found to have a detrimental effect on the kinetics of the process of UPD of H on polycrystalline Pt electrode in 0.5 M H 2 SO 4 , already at the concentration of 1.0 × 10 −5 M RC (with θ H/RC ≈ 0.29). The latter most likely results from the fact that under alkaline conditions (in contrast to the behaviour in acidic solution) surface electrosorption of resorcinol species is significantly limited, due to the existing repulsive interactions, exhibited between the adsorbed RC anions (Pt-RC --to--RC-Pt).…”

“…The exceptional catalytic properties of platinum catalysts have led to wide-ranging research into the electrochemical performance of different organic molecules and wellordered single-crystal Pt planes [1,2]. The current research can be traced back to some earlier works published from this laboratory on the electrochemical reactivity of small organic molecules, including guanidine [3], acetamidine [4], formamidoxime [5], urea [6,7] and single Pt crystals, as well as recently published articles on resorcinol (RC) [8,9] on polycrystalline Pt electrodes, examined in both H 2 SO 4 and NaOH solutions.…”