Electroreduction of nitrogen to ammonia on nanoporous gold

Abstract

The electrochemical reduction of nitrogen (N₂) to ammonia (NH₃) has attracted attention as an emerging alternative to the traditional Haber–Bosch process to synthesize NH₃. Unfortunately, electrocatalytic N₂ reduction processes are still very inefficient. Here we report three-dimensional nanoporous gold (NPG) as an efficient and stable electrocatalyst for the N₂ reduction reaction at room temperature and atmospheric pressure. NPG can deliver a high NH₃ yield rate of 45.7 μg h⁻¹ mg⁻¹_cat. and a high faradaic efficiency of 3.41% at an ultralow potential of −0.10 V versus the reversible hydrogen electrode, in 0.1 M HCl solution. These values are much higher than those obtained for most of the reported electrocatalysts under similar experimental conditions. Structural characterization and density functional theory calculations reveal that the excellent electrocatalytic activity of NPG mainly results from the high density of geometrically required surface steps and kinks.