Nitrogen-Defective Polymeric Carbon Nitride Nanolayer Enabled Efficient Electrocatalytic Nitrogen Reduction with High...

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrochemical nitrogen reduction reaction (NRR) faces challenges in catalyst selectivity and accurate ammonia (NH3) yield measurement.
• Contamination can lead to false-positive results in NH3 detection.

Purpose of the Study:

• To develop a highly selective electrocatalyst for NRR.
• To establish a reliable method for measuring NH3 yield.
• To investigate the role of nitrogen defects in enhancing NRR performance.

Main Methods:

• Synthesis of N-defective carbon nitride on carbon paper (CN/C) electrocatalysts at varying temperatures (500 °C and 600 °C).
• Reliable NH3 yield determination using the slope of the NH3-time plot.
• Characterization of catalyst properties, including N-defect density.
• Verification of NH3 production using isotope 15N2 experiments.
• Further enhancement of N-defects via plasma etching.

Main Results:

• CN/C600 exhibited a higher NH3 production rate (2.9 μg mgcat.-1 h-1 at -0.3 V) compared to CN/C500.
• CN/C600 demonstrated high Faradaic efficiencies (62.1% at -0.1 V, 33.9% at -0.2 V, 16.8% at -0.3 V).
• Increased N-defects correlated with higher NH3 yield, indicating their role in promoting NRR.

Conclusions:

• N-defective carbon nitride is a highly selective electrocatalyst for NRR.
• The slope method provides a reliable approach for quantifying NH3 yield.
• Nitrogen defects are crucial active sites for enhancing electrochemical nitrogen reduction.