The effect of Nafion on electrochemical nitrate reduction over CoRu alloy catalyst

Abstract

In the electrochemical nitrate reduction reaction (eNO3-RR), the microenvironment at the catalyst-electrolyte interface plays a crucial role in regulating reaction kinetics and product selectivity. As a commonly used electrode modifier, Nafion can enhance catalyst performance by adjusting the microenvironment at the catalyst-electrolyte interface. However, the atomic-level interaction mechanisms between Nafion and catalyst surfaces are still not fully understood. This study investigates the eNO3-RR mechanism with Co9Ru1 catalyst, especially how Nafion influences the reaction under alkaline conditions. The results illustrate that Nafion promotes water dissociation to supply protons by reducing the energy barrier, without affecting the proton or nitrate ion (NO3-) transfer distances. Furthermore, Nafion strengthens NO3- adsorption through orbital interactions with adsorbed nitrate (*NO3), thereby promoting the transport of NO3- from the electrolyte to the electrochemical interface. We have determined that the N-side pathway is the most thermodynamically favorable route for eNO3-RR with Nafion-modified Co9Ru1. Notably, Nafion remains inert toward the competing hydrogen evolution reaction (HER) while selectively promoting eNO3-RR. These insights offer a strategic framework for designing catalyst-electrolyte interfaces.