Electrochemical Stability and Degradation Mechanisms of Commercial Carbon-Supported Gold Nanoparticles in Acidic Media

Milutin Smiljanić; Urša Petek; Marjan Bele; Francisco Ruiz-Zepeda; Martin Šala; Primož Jovanovič; Miran Gaberšček; Nejc Hodnik

doi:10.1021/acs.jpcc.0c10033

Electrochemical Stability and Degradation Mechanisms of Commercial Carbon-Supported Gold Nanoparticles in Acidic Media

J Phys Chem C Nanomater Interfaces. 2021 Jan 14;125(1):635-647. doi: 10.1021/acs.jpcc.0c10033. Epub 2021 Jan 6.

Authors

Milutin Smiljanić^{1

2}, Urša Petek¹, Marjan Bele¹, Francisco Ruiz-Zepeda^{1

3}, Martin Šala⁴, Primož Jovanovič¹, Miran Gaberšček^{1

5}, Nejc Hodnik^{1

6}

Affiliations

¹ Department of Materials Chemistry, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia.
² Laboratory for Atomic Physics, Institute for Nuclear Sciences Vinča, University of Belgrade, Mike Alasa 12-14, 11001 Belgrade, Serbia.
³ Department of Physics and Chemistry of Materials, Institute of Metals and Technology, Lepi pot 11, 1000 Ljubljana, Slovenia.
⁴ Department of Analytical Chemistry, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia.
⁵ Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia.
⁶ University of Nova Gorica, Vipavska 13, 5000 Nova Gorica, Slovenia.

Abstract

Electrochemical stability of a commercial Au/C catalyst in an acidic electrolyte has been investigated by an accelerated stress test (AST), which consisted of 10,000 voltammetric scans (1 V/s) in the potential range between 0.58 and 1.41 V_RHE. Loss of Au electrochemical surface area (ESA) during the AST pointed out to the degradation of Au/C. Coupling of an electrochemical flow cell with ICP-MS showed that only a minor amount of gold is dissolved despite the substantial loss of gold ESA during the AST (∼35% of initial value remains at the end of the AST). According to the electrochemical mass spectrometry experiments, carbon corrosion occurs during the AST but to a minor extent. By using identical location scanning electron microscopy and identical location transmission electron microscopy, it was possible to discern that the dissolution of small Au particles (<5 nm) within the polydisperse Au/C sample is the main degradation mechanism. The mass of such particles gives only a minor contribution to the overall Au mass of the polydisperse sample while giving a major contribution to the overall ESA, which explains a significant loss of ESA and minor loss of mass during the AST. The addition of low amounts of chloride anions (10^-4 M) substantially promoted the degradation of gold nanoparticles. At an even higher concentration of chlorides (10^-2 M), the dissolution of gold was rather effective, which is useful from the recycling point of view when rapid leaching of gold is desirable.