Oxygen-Incorporation-Engineered Interfacial Water Modulation on Single-Atom Cu Sites for Enhanced Dilute Nitrate...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• The nitrate reduction reaction (NO3RR) is crucial for environmental remediation and ammonia synthesis.
• Catalyst interfacial microenvironments, influenced by cations, water, and ion adsorption, significantly impact NO3RR efficiency and selectivity.
• Understanding catalyst structural control over these microenvironments is key for developing effective catalytic systems.

Purpose of the Study:

• To develop oxygen-engineered Cu-NCOx single-atom catalysts (SACs) with tunable oxygen functional groups.
• To investigate the role of structural engineering in controlling the interfacial microenvironment for enhanced NO3RR.
• To elucidate the mechanism of nitrate reduction in dilute nitrate solutions.

Main Methods:

• Synthesis of oxygen-engineered Cu-NCOx SACs with asymmetric Cu-N3O1 active sites.
• Electrochemical experiments to evaluate NO3RR performance (Faradaic efficiency, yield rate).
• Theoretical calculations (e.g., DFT) to understand Cu-O coordination, NO3- adsorption, and interfacial water interactions.

Main Results:

• The introduction of Cu-O coordination creates electron-deficient Cu sites, enhancing NO3- adsorption and activation.
• Electron-rich oxygen functionalities effectively trap Na+-hydrated water via electrostatic interactions.
• NO3RR performance exhibits a volcano relationship with interfacial Na+-hydrated water concentration due to competing hydrogen evolution reaction (HER).

Conclusions:

• Oxygen incorporation into Cu SACs is an effective strategy to boost NO3RR in dilute nitrate solutions.
• Precise control over interfacial water structure around asymmetric Cu SACs centers is critical for high performance.
• The optimized Cu-NCO M electrocatalyst achieved 96.7% NH3 Faradaic efficiency and a yield rate of 10.5 mol h-1 gCu-1.