Hexagonal Cobalt Nanosheets for High-Performance Electrocatalytic NO Reduction to NH₃

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis
• Environmental Science

Background:

• Electrocatalytic nitric oxide (NO) reduction is a key strategy for ambient ammonia (NH3) generation.
• It also helps mitigate disruptions to the natural nitrogen cycle.
• Developing efficient electrocatalysts for NO electroreduction remains a significant challenge.

Purpose of the Study:

• To explore efficient electrocatalysts for enhanced NO electroreduction performance.
• To investigate the catalytic activity of hexagonal-close-packed cobalt (hcp-Co) nanosheets for NO reduction.
• To demonstrate a proof-of-concept device utilizing hcp-Co for energy generation.

Main Methods:

• Synthesis of hexagonal-close-packed cobalt (hcp-Co) nanosheets.
• Electrochemical evaluation of NO reduction reaction (NORR) performance.
• Density functional theory (DFT) calculations and NO temperature-programmed desorption experiments.

Main Results:

• hcp-Co nanosheets achieved a high NH3 yield (439.50 μmol cm⁻² h⁻¹) and Faraday efficiency (72.58%).
• Performance surpassed face-centered cubic cobalt (fcc-Co) and other reported electrocatalysts.
• A Zn-NO battery with hcp-Co cathode demonstrated a high power density (4.66 mW cm⁻²).

Conclusions:

• The superior NORR activity of hcp-Co is attributed to unique electron structures and a proton shuttle effect.
• hcp-Co is a highly efficient electrocatalyst for ammonia synthesis from NO.
• The developed Zn-NO battery showcases potential for practical energy applications.