N-doped carbon–iron heterointerfaces for boosted electrocatalytic active and selective ammonia production

Abstract

The electrochemical conversion of waste nitrate (NO 3 − ) to valuable ammonia (NH 3 ) is an economical and environmentally friendly technology for sustainable NH 3 production. It is beneficial for environmental nitrogen pollution management and is also an appealing alternative to the current Haber–Bosch process for NH 3 production. However, owing to the competing hydrogen evolution reaction, it is necessary to design highly efficient and stable electrocatalysts with high selectivity. Herein, we report a rational design of Fe nanoparticles wrapped in N-doped carbon (Fe@N 10 -C) as a high NH 3 selective and efficient electrocatalyst using a metal–organic framework precursor. We constructed a catalyst with new active sites by doping with nitrogen, which activated neighboring carbon atoms and enhanced metal-to-carbon electron transfer, resulting in high catalytic activity. These doped N sites play a key role in the NO 3 − electroreduction. As a result, the Fe@N 10 -C nanoparticles with optimal doping of N demonstrated remarkable performance, with a record-high NO 3 − removal capacity of 125.8 ± 0.5 mg N g cat −1 h −1 and nearly 100 % (99.7 ± 0.1%) selectivity. The catalyst also delivers an impressive NH 3 production rate of 2647.7 μg h −1 cm −2 and high faradaic efficiency of 91.8 ± 0.1%. This work provides a new route for N-doped carbon–iron catalysis application and paves the way for addressing energy and environmental issues.