A metal-free catalyst for electrocatalytic NO reduction to NH₃

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science

Background:

• Electrocatalytic reduction of nitrogen oxides (NOx) to ammonia (NH3) is a key process for environmental remediation and sustainable nitrogen fixation.
• Developing efficient and cost-effective catalysts is crucial for advancing this technology.
• Metal-based catalysts often face challenges related to cost, scarcity, and environmental impact.

Purpose of the Study:

• To investigate the potential of metal-free boron phosphide (BP) as a catalyst for the electrocatalytic reduction of NO to NH3.
• To evaluate the catalytic performance of BP in terms of NH3 selectivity and yield rate.
• To elucidate the underlying catalytic mechanism using theoretical calculations.

Main Methods:

• Electrochemical experiments were conducted to assess the performance of BP for NO reduction.
• Faradaic efficiency and yield rate of NH3 were measured.
• Density Functional Theory (DFT) calculations were employed to understand the reaction pathways and active sites.

Main Results:

• Boron phosphide (BP) exhibited significant catalytic activity for the electrocatalytic reduction of NO to NH3.
• Achieved a high NH3 faradaic efficiency of 83.3% and an NH3 yield rate of 96.6 μmol h⁻¹ cm⁻².
• Outperformed most existing metal-based catalysts in NO reduction to NH3.
• Theoretical analysis revealed that both boron and phosphorus atoms in BP act as dual-active centers, synergistically activating NO and promoting the hydrogenation process while suppressing the hydrogen evolution reaction.

Conclusions:

• Metal-free boron phosphide is a highly effective catalyst for the electrocatalytic reduction of NO to NH3.
• The dual-active sites of B and P atoms in BP are responsible for its superior catalytic performance.
• BP presents a promising alternative to traditional metal catalysts for sustainable ammonia synthesis and environmental applications.