Acetonitrile Adsorption on Pt Single-Crystal Electrodes and Its Effect on Oxygen Reduction Reaction in Acidic and Alkaline Aqueous Solutions

Abstract

The adsorption and reactivity of acetonitrile (CH 3 CN) have been studied on Pt(111) and Pt(100) electrodes in 0.1 M HClO 4 and 0.1 M NaOH solutions with CH 3 CN concentrations ranging from 10-3 M to 1 M. Cyclic voltammetry results show that these processes are structure sensitive and that the hydrogen adsorption/desorption region is partially blocked on Pt(111) in acidic solutions while the inhibition is almost complete on Pt(100) in both acidic and alkaline media. However, for Pt(111) hydrogen adsorption is practically unaltered in the 0.1 M NaOH electrolyte. In-situ infrared measurements and DFT calculations suggest that rehybridized adsorbed acetonitrile reacts with adsorbed hydroxyl species at high potentials forming a hydroxylated adsorbed species.

A Detrimental Effect of Acetonitrile on the Kinetics of Underpotentially Deposited Hydrogen and Hydrogen Evolution Reaction, Examined on Pt Electrode in H2SO4 and NaOH Solutions

“…0.50 V) appeared over the double-layer charging potential range of the CV profile (0.40-0.60 V/RHE). The latter observations are in-line with those originally presented in [7,8], where a two-electron reduction-oxidation process occurs over the potential range about 0.40-0.60 V with a reactive species being in the chemisorbed state.…”

“…Acetonitrile, CH 3 CN (AcN) is a simple-structure, highly polar and volatile organic solvent, commonly used in numerous industrial applications, including: extraction, plastics molding and casting and battery technologies. Its presence in the air could have a substantial detrimental effect on the catalytic performance of otherwise highly reactive, noble metal-based electrochemical catalysts [7][8][9][10][11][12].…”

Controlling palladium morphology in electrodeposition from nanoparticles to dendritesviathe use of mixed solvents

“…53 MeCN has been shown to adsorb on Pt in a similar fashion, with the C-CuN plane parallel to the surface. 54,55 Whilst MeCN coverage is not high enough to completely impede electrodeposition, we suggest it plays a significant role in slowing down the growth process, retarding (or blocking) both ad-atom mobility on the surface of growing nanostructures and coalescence events. On Pt, for example, MeCN adsorption has been shown to drastically decrease limiting current densities for the oxygen reduction reaction (ORR) and shift the onset potential to more negative values in aqueous (acidic) media.…”

“…On Pt, for example, MeCN adsorption has been shown to drastically decrease limiting current densities for the oxygen reduction reaction (ORR) and shift the onset potential to more negative values in aqueous (acidic) media. 54 Crystal orientation was also found to influence the strength of the MeCN-Pt interaction. 54,55 As we expect similar behaviour for MeCN-Pd for future studies it would be of interest to simulate the strength of MeCN-Pd chemisorption on different crystal faces through density functional theory (DFT) simulations.…”

“…54 Crystal orientation was also found to influence the strength of the MeCN-Pt interaction. 54,55 As we expect similar behaviour for MeCN-Pd for future studies it would be of interest to simulate the strength of MeCN-Pd chemisorption on different crystal faces through density functional theory (DFT) simulations.…”