Theoretical Insights into Metal-Catalyzed Associative Electrochemical Conversion of NOx in Aqueous Solution
Year: 2025
Type: article
Abstract: The present study investigated a mechanistic analysis of the electrocatalytic reduction of nitrogen oxides (NO x; x = 1, 2) into ammonia (NH 3 ) on flat surfaces of selected middle-to-late d -block metals, viz., Fe, Co, Ni, Cu, Zn, Mo, Ru, Rh, Pd, Ag, Os, Ir, Pt, and Au. Our DFT calculations were carried out in aqueous solution via an implicit solvation model, also providing insights into the impact of the pH on the reduction process. At a mechanistic level, the first four reductive steps entail the O-hydrogenation from NO x via the path *NO 2 → *NO 2 H → *NO (+H 2 O) → *NOH → *N (+H 2 O). Subsequently, the as-generated N adatoms are hydrogenated to form ammonia following the path *N → *NH → *NH 2 → *NH 3 . In this mechanism, the conversions of *NO 2 into *NO 2 H and *NO into *NOH were generally identified as the rate-determining steps. In addition, binding of NO 2 and NO has been computed to be stronger than NH 3 adsorption in most cases, which prevents ammonia poisoning on the metal surfaces. Finally, our results show the existence of periodic behaviors in all of the modeled stages of the NO x reduction mechanism, revealing strong correlation among the free energies involved in the steps *NO to *NOH and *NOH or *N to *NH x at different levels of hydrogenation.
Language: English
Subfield: Catalysis
Field: Chemical Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W4409461982