OH^–···Au Hydrogen Bond and Its Effect on the Oxygen Reduction Reaction on Au(100) in Alkaline Media

Abstract

Using ab initio molecular dynamics simulations with fully solvated ions, we demonstrate that solvated OH– forms a stable hydrogen bond with Au(100). Unlike the hydrogen bond between H2O and Au reported previously, which is more favorable for negatively charged Au, the OH–···Au interaction is stabilized when a small positive charge is added to the metal slab. For electro-catalysis, this means that while OH2···Au plays a significant role in the hydrogen evolution reaction, OH–···Au could be a significant factor in the oxygen reduction reaction in alkaline media. It also points to a fundamental difference in the mechanism of oxygen reduction between gold and platinum electrodes.

Circumventing the Sabatier Principle in Electrocatalysis: the Case of Oxygen Reduction Reaction on Au(100) in Alkaline Medium

“…15 The higher value on Au(100) is partly due to the smaller OH* adsorption energy. Furthermore, as recently demonstrated in our AIMD simulations, 52…”

“…While the production of OH* is known to be promoted by the presence of water, [17][18] OH* desorption could be a key factor in determining the ORR current. 52 Again, it's instructive to compare the relevant steps on Pt(111) and Au(100). Hydrogenation of O* could go through two possible channels, either…”

Double-Layer Distribution of Hydronium and Hydroxide Ions in the Air–Water Interface

“…Aqueous interfaces are ubiquitous in nature and in engineering applications. − The acid–base chemistry of aqueous interfaces is critical in fields as diverse as biology, atmospheric science, geochemistry, and engineering. ,, The accumulated water self-ions at aqueous interfaces, hydroxide OH – and hydronium H 3 O + , may not only influence the interfacial reactions by changing electrostatic field, − such as oxygen reduction reaction, hydrogen evolution reaction, , as well as the formation reactions of hydrogen peroxide, − ammonia, , sulfate and phenol, but also directly participate in interfacial physical and chemical processes. − ,, Great efforts have been devoted to exploring the preference of water self-ions in the interfaces, as well as their electronic and geometrical structures and dynamic properties for the deep understanding of interfacial acid–base chemistry. − However, the acid–base chemical characteristics near the interfaces are still elusive, ,,− and even whether excess hydroxides and/or hydroniums accumulate in the air–water interface remains controversial. − ,− …”

“…1−4 The acid−base chemistry of aqueous interfaces is critical in fields as diverse as biology, atmospheric science, geochemistry, and engineering. 1,5,6 The accumulated water self-ions at aqueous interfaces, hydroxide OH − and hydronium H 3 O + , may not only influence the interfacial reactions by changing electrostatic field, 6−9 such as oxygen reduction reaction, 10 hydrogen evolution reaction, 9,11 as well as the formation reactions of hydrogen peroxide, 12−14 ammonia, 15,16 sulfate 17 and phenol, 18 but also directly participate in interfacial physical and chemical processes. [9][10][11][12][13][14]19,20 Great efforts have been devoted to exploring the preference of water self-ions in the interfaces, as well as their electronic and geometrical structures and dynamic properties for the deep understanding of interfacial acid−base chemistry.…”

Electrocatalysis of Oxygen Reduction on Te-Modified Platinum Stepped Crystal Surfaces

“…For that, it is necessary to understand the ORR mechanism and factors that affect ORR kinetics on the electrocatalysts . However, the complex catalyst structure in practical electrode materials limits the in-depth study of ORR kinetics. − Single-crystal electrodes with well-defined surfaces and a controlled atomic arrangement − are of great help in elucidating the reaction mechanism and unraveling the structure–activity relationship. Systematic studies of the platinum stepped surfaces with different terrace widths have provided rich information, such as the chemical properties of the electrode/electrolyte interface at the atomic level and how these properties affect its behavior. − The information gained from such studies has shed important insights into real electrocatalysts in PEMFCs. − …”