Beyond Conventional Doping: Sulfur-Induced Electronic and Interfacial Dynamics for Advanced Nitrate Reduction

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrochemical nitrate reduction reaction (NO₃⁻RR) to ammonia (NH₃) is key for sustainable synthesis and environmental remediation.
• Sluggish kinetics, inefficient proton-coupled electron transfer (PCET), and poor electrocatalyst design hinder NO₃⁻RR.
• Current methods overlook interfacial water dynamics, focusing only on bulk electronic properties.

Purpose of the Study:

• To develop a dual-functional sulfur-doping strategy in Co₃O₄ (S-Co₃O₄) for enhanced NO₃⁻RR.
• To simultaneously improve bulk conductivity and interfacial proton transfer in electrocatalysts.
• To investigate the synergistic effects of electronic and interfacial modifications on NO₃⁻RR performance.

Main Methods:

• Sulfur doping of Co₃O₄ to create S-Co₃O₄.
• Benzene sulfonyl chloride blocking experiments to probe interfacial water.
• In situ spectroscopic analyses to study electronic structure and water behavior.
• Kinetic isotope effect studies to understand reaction mechanisms.

Main Results:

• Sulfur doping narrows the bandgap of Co₃O₄, enhancing bulk charge transport.
• Sulfur doping disrupts the water hydrogen-bond network at the interface.
• Weakly hydrogen-bonded water facilitates proton supply for nitrate hydrogenation.
• S-Co₃O₄ exhibits improved electrocatalytic performance for NO₃⁻RR.

Conclusions:

• The "electronic-interfacial synergy" strategy offers a new paradigm for electrocatalyst design.
• Optimizing interfacial water dynamics is crucial for efficient PCET-driven reactions.
• This approach advances sustainable energy conversion and environmental remediation technologies.