Highly Selective N2 Electroreduction to NH3 Using a Boron-Vacancy-Rich Diatomic NbB Catalyst

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• The Haber-Bosch process for ammonia synthesis is energy-intensive and polluting.
• Electrochemical nitrogen reduction reaction (NRR) offers a sustainable alternative but faces challenges in N2 activation and hydrogen evolution selectivity.
• Developing efficient catalysts is crucial for advancing ambient NRR.

Purpose of the Study:

• To investigate the potential of niobium diboride (NbB2) nanoflakes as a catalyst for the ambient electrochemical NRR.
• To understand the catalytic mechanism behind NbB2's performance in ammonia synthesis.
• To evaluate the selectivity and durability of NbB2 for NRR applications.

Main Methods:

• Synthesis of NbB2 nanoflakes (NFs).
• Electrochemical testing of NbB2 NFs for NRR.
• Density functional theory (DFT) calculations to elucidate the N2 adsorption and activation mechanism.

Main Results:

• NbB2 NFs demonstrated excellent selectivity and durability for NRR.
• Achieved an ammonia production rate of 30.5 µg h⁻¹ mg⁻¹cat and a high Faraday efficiency (FE) of 40.2%.
• DFT calculations revealed that B vacancies on NbB2 surfaces facilitate N2 adsorption and activation by stretching the N≡N bond.

Conclusions:

• NbB2 nanoflakes are highly effective electrocatalysts for ambient ammonia synthesis via NRR.
• The presence of B vacancies is key to the catalyst's high selectivity and performance.
• This study highlights diatomic catalysis as a promising strategy for engineered N2 adsorption and activation in NRR.