Surface-Engineered Molybdenum Oxide with Cucurbit[6]uril for Enhanced Nitrogen Reduction Electrocatalysis

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrocatalytic nitrogen reduction (NRR) is a sustainable method for ammonia (NH3) production.
• Key challenges include low N2 solubility, high N2 activation energy, and competing hydrogen evolution reaction (HER).

Purpose of the Study:

• To develop an efficient catalyst for aqueous NRR by addressing limitations of N2 activation and HER.
• To investigate the role of supramolecular engineering in enhancing NRR performance.

Main Methods:

• Immobilization of cucurbit[6]uril (CB[6]) onto molybdenum oxide (MoO2) to create CB[6]@MoO2 catalyst.
• Electrocatalytic performance evaluation in a flow cell using Cs2SO4 electrolyte.
• Mechanistic studies using host-guest complex formation and interfacial electric field analysis.

Main Results:

• CB[6]@MoO2 achieved a high NH3 production rate (27.7 µg h-1 mg-1) and Faradaic efficiency (25.3%) at -0.35 V.
• The catalyst significantly outperformed bare MoO2.
• Mechanistic studies confirmed N2 stabilization, HER suppression, and enhanced N2 activation via CB[6] encapsulation and electric field induction.

Conclusions:

• Supramolecular surface engineering with CB[6] on MoO2 effectively enhances NRR efficiency.
• The strategy addresses N2 solubility, activation barriers, and HER competition in aqueous NRR.
• This work demonstrates a promising approach for sustainable ammonia synthesis.