Electrochemical ammonia synthesis via nitrate reduction on Fe single atom catalyst

Abstract

Electrochemically converting nitrate, a widespread water pollutant, back to valuable ammonia is a green and delocalized route for ammonia synthesis, and can be an appealing and supplementary alternative to the Haber-Bosch process. However, as there are other nitrate reduction pathways present, selectively guiding the reaction pathway towards ammonia is currently challenged by the lack of efficient catalysts. Here we report a selective and active nitrate reduction to ammonia on Fe single atom catalyst, with a maximal ammonia Faradaic efficiency of ~ 75% and a yield rate of up to ~ 20,000 μg h−1 mgcat.−1 (0.46 mmol h−1 cm−2). Our Fe single atom catalyst can effectively prevent the N-N coupling step required for N2 due to the lack of neighboring metal sites, promoting ammonia product selectivity. Density functional theory calculations reveal the reaction mechanisms and the potential limiting steps for nitrate reduction on atomically dispersed Fe sites.

Subnanometric alkaline-earth oxide clusters for sustainable nitrate to ammonia photosynthesis

“…From an energy viewpoint, nitrate ions (NO 3 − ), as a sustainable N-containing alternative, can be disintegrated at lower dissociation energy of 204 kJ mol −1 , contributing to an accelerated reaction kinetics for NH 3 synthesis 9 – 13 . Besides, the highest valence state of N-element in NO 3 − ensures that the deep reduction reaction can be achieved for selective NH 4 + synthesis.…”

Efficient electrocatalytic reduction of nitrate to nitrogen gas by a cubic Cu2O film with predominant (111) orientation

“…16,17 Fe-based electrodes were also reported for nitrate electrocatalytic reduction with high selectivity for N 2 , 18 and for ammonia production as well in other reports. 19 It is well known that Cu has an outstanding capacity to inhibit the hydrogen evolution reaction, which could be the most primary competing reduction on the cathode, resulting in high faradaic efficiency for the target reaction. Moreover, Cu-based materials have attracted increasing attention for reduction of nitrate due to additional advantages, for instance, low cost compared with other noble metals.…”

Shell isolated nanoparticle enhanced Raman spectroscopy for mechanistic investigation of electrochemical reactions

“…The Haber–Bosch process, which requires high temperatures and pressures, is mainly used to manufacture NH 3 industrially. Industrial NH 3 production causes a 1.44% increase in global CO 2 emissions because of its harsh synthesis conditions [ 72 ]. Currently, the removal of nitrate from industrial wastewater and its electrochemical conversion into NH 3 has been an important topic in the environmental research field.…”