High-performance electrochemical nitrate reduction to ammonia under ambient conditions using NiFe2O4 nanosheet arrays

Abstract

Ambient ammonia synthesis via the electrochemical reduction of nitrate (NO₃⁻) offers us a sustainable alternative to the industrial energy-intensive Haber–Bosch process. Here, we report on the development of NiFe₂O₄ nanosheet arrays on carbon cloth (NiFe₂O₄/CC) for high-efficiency NH₃ electrosynthesis via the selective reduction of NO₃⁻ under ambient conditions. When operated in 0.1 M phosphate-buffered solution with additional 0.1 M NaNO₃, such NiFe₂O₄/CC achieves a remarkable faradaic efficiency of 96.6% and a high NH₃ yield of up to 10.3 mg h⁻¹ cm⁻². Furthermore, it possesses excellent electrochemical and structural stability. The theoretical calculations reveal that the metallic NiFe₂O₄ surface has strong interactions with NO₃⁻ and can seriously inhibit the HER aiding in more efficient NO₃⁻ reduction to NH₃.