Boosting Electrocatalytic Nitrate Reduction through Enhanced Mass Transfer in Cu-Bipyridine 2D Covalent Organic...

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrocatalytic nitrate reduction (NO₃RR) is vital for environmental remediation and ammonia synthesis.
• Efficient NO₃RR requires optimized catalytic interfaces and mass transfer.
• Eight electrons and nine protons are involved in the NO₃RR process.

Purpose of the Study:

• To design and fabricate advanced catalytic interfaces for enhanced NO₃RR.
• To improve ammonia yield rates and Faradaic efficiency (FE) through rational catalyst design.
• To investigate the role of morphology and interface engineering in NO₃RR performance.

Main Methods:

• Fabrication of crystalline 2D covalent organic framework (COF) films.
• Incorporation of a Copper-bipyridine (Cu-bipyridine) catalytic interface within the COF.
• In situ characterizations and theoretical calculations to elucidate reaction mechanisms.

Main Results:

• Achieved high FE (92.7%) and NH₃ yield rate (14.9 mg·h⁻¹cm⁻²) in 0.5 M nitrate.
• Demonstrated superior performance compared to bulk catalysts and most reported NO₃RR electrocatalysts.
• Film-like morphology significantly enhanced mass transfer across the Cu-bipyridine interface.

Conclusions:

• The 2D COF film structure with exposed Cu-bipyridine sites optimizes mass transfer and catalytic activity.
• Cu sites activate nitrate, while bipyridine facilitates water dissociation and proton-coupled electron transfer.
• Rational control of morphology is a viable strategy to boost catalyst performance in NO₃RR.