Regulating Interfacial Microenvironment in Aqueous Electrolyte via a N2 Filtering Membrane for Efficient Electrochemical Ammonia Synthesis

Abstract

Electrochemical synthesis of ammonia (NH₃) in aqueous electrolyte has long been suffered from poor nitrogen (N₂) supply owing to its low solubility and sluggish diffusion kinetics. Therefore, creating a N₂ rich microenvironment around catalyst surface may potentially improve the efficiency of nitrogen reduction reaction (NRR). Herein, a delicately designed N₂ filtering membrane consisted of polydimethylsiloxane is covered on catalyst surface via superspreading. Because this membrane let the dissolved N₂ molecules be accessible to the catalyst but block excess water, the designed N₂ rich microenvironment over catalyst leads to an optimized Faradaic efficiency of 39.4% and an NH₃ yield rate of 109.2 µg h^-1 mg^-1, which is superior to those of the most report metal-based catalysts for electrochemical NRR. This study offers alternative strategy for enhancing NRR performance.

Keywords: N2 filtering membrane; N2 rich microenvironment; ammonia synthesis; nitrogen reduction reaction; polydimethylsiloxane.