Hydrogen binds significantly weaker on metal surfaces in an aqueous electrolyte environment than at solid-gas interfaces. The impact of the liquid phase environment is complex and in addition to a competition between solvent components and hydrogen for sorption sites, part of the weaker bonding is caused by differences in the sorption entropy induced by ordering in the Helmholtz layer and by the electronic impact of the dominating H++e- &lt;--&gt; H redox reaction. Understanding the role of this relatively weakly adsorbed hydrogen (in equilibrium with the gas phase) and the presence of underpotentially deposited hydrogen, which is not reactive toward hydrogenation of organic substrates, is critical for describing and utilizing adsorbed hydrogen for chemical reactions. External electric potential and the chemical composition of the aqueous solution (pH, ionic strength) influences the binding of hydrogen and influences the impact varying the chemical potential of H2 on hydrogenation rates and selectivities.

Hydrogen binding at metal - aqueous phase interfaces and its impact on hydrogenation rates

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.