Enabling Effective Electrocatalytic N₂ Conversion to NH₃ by the TiO₂ Nanosheets Array under Ambient Conditions

Area of Science:

• Materials Science
• Electrochemistry
• Sustainable Energy

Background:

• Ammonia (NH3) is a key energy carrier and chemical feedstock.
• Electrochemical nitrogen reduction reaction (NRR) offers a sustainable route to ammonia synthesis.
• Efficient electrocatalysts are crucial for overcoming the challenge of nitrogen activation.

Purpose of the Study:

• To investigate the efficacy of TiO2 nanosheets on a Ti plate (TiO2/Ti) as an electrocatalyst for NRR.
• To evaluate the performance of TiO2/Ti in terms of ammonia yield, Faradaic efficiency, and selectivity.
• To understand the role of oxygen vacancies in enhancing NRR activity.

Main Methods:

• Electrochemical synthesis of TiO2 nanosheets array on a Ti plate.
• Testing the TiO2/Ti electrode in 0.1 M Na2SO4 electrolyte for NRR.
• Quantification of ammonia yield and Faradaic efficiency at -0.7 V vs reversible hydrogen electrode.
• Analysis of electrochemical stability and selectivity.

Main Results:

• TiO2/Ti achieved a high NH3 yield of 9.16 × 10^-11 mol s^-1·cm^-2.
• A Faradaic efficiency of 2.50% for NH3 formation was recorded at -0.7 V vs RHE.
• The catalyst demonstrated excellent selectivity and electrochemical stability.
• In situ generated oxygen vacancies were identified as key to enhanced N2 adsorption and activation.

Conclusions:

• TiO2/Ti is a highly effective electrocatalyst for ambient NRR in aqueous media.
• The presence of oxygen vacancies significantly boosts the NRR performance.
• This finding presents a promising pathway for sustainable ammonia production.