Unconventional redox mechanism of gold surfaces revealed by sum frequency generation

Ahmed M. El-Zohry

doi:10.1117/12.3001104

12 March 2024 Unconventional redox mechanism of gold surfaces revealed by sum frequency generation

Ahmed M. El-Zohry

Proceedings Volume 12874, Nanoscale and Quantum Materials: From Synthesis and Laser Processing to Applications 2024; 1287408 (2024) https://doi.org/10.1117/12.3001104
Event: SPIE LASE, 2024, San Francisco, California, United States

Abstract

Combining ultrashort laser pulses at an interface can generate an informative signal called SFG (sum frequency generation). SFG can reveal information about an interface with a thickness of nanometers. Such information can be utilized for instance to understand surface properties under the catalytic process. Herein, we utilized the second-order susceptibility generated from the gold surface to monitor the redox mechanism of gold. Gold is a standard metal surface that is commonly utilized to study surface redox processes such as water oxidation and hydrogen production processes. We found that the redox behavior of gold surfaces, using SFG, adds new mechanistic dimensions to the known mechanism from electrochemistry. For instance, in an acidic medium, two different gold oxides can be formed, the primary one is completely reversible, while the secondary one is not. Such a redox mechanism can lead to stratified gold layers, in which buried gold oxides can be formed. Such stratified structure has been also confirmed by the complementary XPS technique. A similar gold redox mechanism has been found in the basic medium; however, SFG shows that top-atomic gold surface layers can be more active than those in an acidic medium, which can illustrate the catalytic activity of the gold surface layer in the basic medium more than those in the acidic medium. All these implications revealed by SFG about gold will be discussed in my presentation along with the expected challenges to electro-catalysis processes.

Conference Presentation

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Ahmed M. El-Zohry "Unconventional redox mechanism of gold surfaces revealed by sum frequency generation", Proc. SPIE 12874, Nanoscale and Quantum Materials: From Synthesis and Laser Processing to Applications 2024, 1287408 (12 March 2024); https://doi.org/10.1117/12.3001104

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