Efficient interlayer confined nitrate reduction reaction and oxygen generation enabled by interlayer expansion

Area of Science:

• Electrochemistry
• Materials Science
• Environmental Science

Background:

• Electrochemical nitrate reduction to ammonia offers a sustainable route for pollution control and ammonia synthesis.
• Existing catalysts typically perform single electrode reactions, limiting bifunctional applications.
• Developing bifunctional catalysts for both nitrate reduction and oxygen evolution is crucial for efficient overall water electrolysis.

Purpose of the Study:

• To develop an efficient bifunctional catalyst for both nitrate reduction reaction (NRR) and oxygen evolution reaction (OER).
• To investigate the role of Fe-doping and expanded interlayer spacing in α-Ni(OH)2 for catalytic activity.
• To demonstrate the catalyst's performance in overall water electrolysis for ammonia production and pollution remediation.

Main Methods:

• Synthesis of Fe-doped layered α-Ni(OH)2 with expanded interlayer spacing.
• Electrochemical characterization including cyclic voltammetry and chronoamperometry.
• In situ Raman spectroscopy to study reaction mechanisms.
• Performance evaluation in overall water electrolysis.

Main Results:

• Fe-doped α-Ni(OH)2 exhibits bifunctional catalytic activity for NRR and OER.
• Expanded interlayer spacing facilitates in situ potassium ion intercalation, triggering reactions.
• High ammonia yield rate (8.1 mol gcat.-1 h-1) and faradaic efficiency (97.5%) achieved for NRR.
• Reduced overpotential for OER (254 mV at 10 mA cm-2) and stable performance in overall electrolysis (24.8 mA cm-2 at 2.0 V for 50 h).

Conclusions:

• Fe-doped layered α-Ni(OH)2 is an efficient bifunctional catalyst for electrochemical nitrate conversion and water splitting.
• The catalyst's performance is attributed to expanded interlayer spacing and in situ ion intercalation.
• This work presents a promising strategy for simultaneous water pollution control and valuable chemical production.