Self-Supported Pd Nanorod Arrays for High-Efficient Nitrate Electroreduction to Ammonia

Area of Science:

• Electrochemistry
• Materials Science
• Environmental Engineering

Background:

• Electrochemical nitrate reduction to ammonia (NH3) is a key process for wastewater remediation and sustainable ammonia synthesis.
• Current electrocatalysts face challenges with low efficiency and hydrogen evolution side reactions.
• Developing efficient and stable catalysts is crucial for industrial applications.

Purpose of the Study:

• To develop a high-performance electrocatalyst for nitrate reduction reaction (NO3- RR) to ammonia.
• To investigate the catalytic mechanism and stability of the proposed electrocatalyst.
• To evaluate the potential for large-scale industrial application.

Main Methods:

• Fabrication of self-supported Palladium (Pd) nanorod arrays on porous nickel foam (NF).
• Electrochemical characterization including cyclic voltammetry and chronoamperometry.
• In situ Fourier-transform infrared spectroscopy (FTIR) and density functional theory (DFT) calculations.
• Assessment of ammonia yield rate, Faradaic efficiency, and long-term stability.

Main Results:

• The Pd/NF electrode demonstrated a high NH3 yield rate of 1.52 mmol cm-2 h-1 and a Faradaic efficiency of 78% at -1.4 V vs RHE.
• The catalyst exhibited excellent stability, maintaining high performance over 50 cycles (25 h).
• A large-area (25 cm2) Pd/NF electrode achieved an NH3 yield of 174.25 mg h-1, indicating scalability.

Conclusions:

• Self-supported Pd nanorod arrays on nickel foam are highly effective for electrochemical nitrate reduction to ammonia.
• The catalyst's nanostructure enhances active sites for nitrate activation and suppresses hydrogen evolution.
• This work presents a promising strategy for designing advanced catalysts for sustainable ammonia production and wastewater treatment.