The strong catalytic effect of Pb(ii) on the oxygen reduction reaction on 5 nm gold nanoparticles

Abstract

Citrate-capped gold nanoparticles (AuNPs) of 5 nm in diameter are synthesized via wet chemistry and deposited on a glassy carbon electrode through electrophoresis. The kinetics of the oxygen reduction reaction (ORR) on the modified electrode is determined quantitatively in oxygen-saturated 0.5 M sulphuric acid solution by modelling the cathode as an array of interactive nanoelectrodes. Quantitative analysis of the cyclic voltammetry shows that no apparent ORR electrocatalysis takes place, the kinetics on AuNPs being effectively the same as on bulk gold. Contrasting with the above, a strong ORR catalysis is found when Pb(2+) is added to the oxygen saturated solution or when the modified electrode is cycled in lead alkaline solution such that lead dioxide is repeatedly electrodeposited and stripped off on the nanoparticles. In both cases, the underpotential deposition of lead on the gold nanoparticles is found to be related to the catalysis.

Understanding mass transport influenced electrocatalysis at the nanoscale via numerical simulation

“…The electron-transfer rate constant of the rate-determining step and the transfer coefficient measured from AuNPs of 5~40 nm radii are almost identical with the results on the Au macroelectrode, showing there is no significant nanoeffect on the electrocatalytic kinetics for ORR on Au. [68][69] However, a negative effect was found for 2 nm AuNPs,…”

“…Nanoeffects on the ORR kinetics for a series of gold nanoparticles (AuNP) of 2~40 nm radii were investigated by Compton et al via comparing the kinetic parameters measured from AuNP modified electrodes and a gold macroelectrode. 62,[68][69] The mechanism of ORR was inferred to be the twoelectron-two-proton transfer mechanism and the product to be H2O2: 68…”

Oxygen reduction reaction features in neutral media on glassy carbon electrode functionalized by chemically prepared gold nanoparticles

“…− that follow the transfer of the first electron [31,32]. In both media, electrochemical techniques such as cyclic voltammetry [33,34], impedance spectroscopy [35], rotating disk [36,37], and ring disk electrode [24,38] and SECM experiments [27] have allowed kinetic features to be reached. Surprisingly, very few works dealing with ORR on AuNPs in neutral media have been reported in the literature [39][40][41] although it would be of great interest for applications such as environmental survey [42] or clinical analysis [43].…”

Shape‐Dependent Electrocatalysis: Oxygen Reduction on Carbon‐Supported Gold Nanoparticles

“…However, a strong enhancement of electrocatalytic activity was observed in the presence of small amounts of underpotentially deposited lead. [28] Sarapuu et al studied the electroreduction of O 2 on thin Au films prepared by vacuum evaporation and found that the specific activity (SA) does not depend on film thickness in H 2 SO 4 solution, but in KOH solution the SA decreases with film thickness. [29,30] Zeis et al have demonstrated the high electrocatalytic activity of nanoporous Au for the reduction of O 2 and H 2 O 2 .…”