Co-Ni Synergy Engineered in a Perovskite for Highly Selective Nitrate Electroreduction to Ammonia

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Perovskite oxides are explored as electrocatalysts for nitrate reduction reaction (NO₃RR) to ammonia.
• Challenges include low ammonia selectivity, yield, and suppression of competing reactions.

Purpose of the Study:

• To develop a novel multimetallic perovskite electrocatalyst for efficient NO₃RR to ammonia.
• To investigate the catalytic mechanism and performance of the new material.

Main Methods:

• Synthesis of La_0.5Sr_0.5Co_0.5Ni_0.5O₃ (LSCNO) via a sol-gel method.
• Density functional theory (DFT) calculations to understand electronic structure and reaction kinetics.
• Electrochemical testing in a flow-cell system and assembly of a Zn-NO₃^- battery.

Main Results:

• LSCNO demonstrated high Faradaic efficiency (94.96%) and ammonia yield (9475.9 μg h^-1 cm^-2) at -0.5 V vs RHE.
• Excellent stability was observed over 12 cycles and prolonged operation.
• The Zn-NO₃^- battery achieved a peak power density of 10.19 mW cm^-2 with long-term durability.

Conclusions:

• Ni doping in LSCNO optimizes electronic structure, lowering the energy barrier for NO₃RR.
• LSCNO is a highly efficient and stable electrocatalyst for nitrate-to-ammonia conversion.
• The catalyst shows significant potential for nitrogen resource recovery and sustainable energy storage.