Electrochemical Nitric Oxide Reduction on Metal Surfaces

Area of Science:

• Electrochemistry
• Catalysis
• Environmental Science

Background:

• Electrocatalytic denitrification is a key technology for removing nitrogen oxides (NOx).
• Understanding catalyst selectivity and activity is crucial for optimizing NOx electroreduction (NOx RR).
• Current research lacks a clear strategy for controlling product distribution in NOx RR.

Purpose of the Study:

• To elucidate the selectivity and activity of various catalysts for NOx electroreduction (NOx RR).
• To establish a classification of metal catalysts based on their binding affinities for *NO and *H.
• To provide a strategic framework for enhancing selectivity in NOx RR.

Main Methods:

• Electrocatalytic experiments were conducted to evaluate catalyst performance.
• Metal catalysts were classified based on *NO and *H binding energies.
• Activity-volcano plots were used to assess catalytic activity.

Main Results:

• Copper (Cu) selectively produces ammonia (NH3) by binding *NO but not *H, analogous to CO2 electroreduction.
• Cu exhibits high activity for NOx RR, as indicated by an activity-volcano relationship.
• Metals that do not bind NO terminate the reaction at NO, similar to CO to CO conversion.

Conclusions:

• Catalyst selectivity in NOx RR can be controlled by tuning *NO and *H binding energies.
• Copper presents a promising catalyst for selective ammonia synthesis via NOx electroreduction.
• Further research into N coupling mechanisms at higher potentials may reveal pathways to N2O formation.