Interfacial Engineering of MoxSy via Boron-Doping for Electrochemical N2-to-NH3 Conversion.

Abstract

The electrocatalytic synthesis of ammonia (NH₃) through the nitrogen reduction reaction (NRR) under ambient temperature and pressure is emerging as an alternative approach to the conventional Haber-Bosch process. However, it remains a significant challenge due to poor kinetics, low nitrogen (N₂) solubility in aqueous electrolytes, and the competing hydrogen evolution reaction (HER), which can significantly impact NH₃ production rates and Faradaic efficiency (FE). Herein, a rationally designed boron-doped molybdenum sulfide (B-Mo-Mo_xS_y) electrocatalyst is reported that effectively enhances N₂ reduction to  NH₃ with an onset potential of -0.15 V versus RHE, achieving a FE of 78% and an NH₃ yield of 5.83 µg h⁻¹ cm⁻² in a 0.05 m H₂SO₄(aq). Theoretical studies suggest that the effectiveness of NRR originates from electron density redistribution due to boron (B) doping, which provides an ideal pathway for nitrogenous species to bind with electron-deficient B sites. This work demonstrates a significant exploration, showing that Mo-based electrocatalysts are capable of facilitating artificial N₂ fixation.