N₂ Electroreduction to NH₃ by Selenium Vacancy-Rich ReSe₂ Catalysis at an Abrupt Interface

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Vacancy engineering is a key strategy for enhancing electrocatalysis.
• Poor selectivity, particularly competition from hydrogen evolution reaction (HER), limits nitrogen reduction reaction (NRR) applications.
• Selenium vacancies in ReSe2 can enhance electroactivity but require strategies to improve NRR selectivity.

Purpose of the Study:

• To investigate the effect of selenium vacancies in ReSe2 on electrocatalytic activity for NRR.
• To develop a method to enhance NRR selectivity by suppressing HER.
• To achieve high ammonia yield and Faradaic efficiency for NRR.

Main Methods:

• Density functional theory (DFT) calculations to understand electronic structure changes.
• Fabrication of selenium vacancy-rich ReSe2 encapsulated within carbonized bacterial cellulose (V_r-ReSe2@CBC) nanofibers.
• Electrochemical measurements to evaluate NRR performance and HER selectivity.
• Surface characterization including nitrogen bubble adhesion, hydrophilicity, and COMSOL simulations.

Main Results:

• DFT calculations showed selenium vacancies shift the d-band center of ReSe2, enhancing electroactivity.
• The V_r-ReSe2@CBC structure demonstrated a Faradaic efficiency of 42.5% and ammonia yield of 28.3 μg h⁻¹ cm⁻² at -0.25 V.
• Hydrophobic CBC layers effectively prevented water coverage, exposing active sites for N2 reduction and suppressing HER.

Conclusions:

• Encapsulating V_r-ReSe2 within hydrophobic CBC layers is an effective strategy to enhance NRR selectivity.
• The proposed material design significantly boosts ammonia production while suppressing competing HER.
• This work offers a promising approach for developing efficient electrocatalysts for nitrogen reduction.