Favoring the Originally Unfavored Oxygen for Enhancing Nitrogen-to-Nitrate Electroconversion

Current nitrate production involves a two-step thermochemical process that is energy-intensive and generates substantial CO₂ emissions. Sustainable NO₃^- production via the nitrogen electrooxidation reaction powered by renewable electricity is highly desirable, but the Faradaic efficiency (FE) at high production rates is unsatisfactory due to competition from the oxygen evolution reaction (OER). In this study, we propose reengineering the catalyst’s microstructure-to-macroenvironment interface by particularly utilizing the previously considered unfavored oxygen from the OER. We demonstrate that the re-engineered interface facilitates a record-breaking FE of 35.52% under 8 atm air, with an impressive increase in FE (41.56%) observed during a continuous electrochemical process lasting for 60 h due to the in situ formation of the O₂-rich macro-interface environment. The revelation is anticipated to furnish groundbreaking perspectives for the reaction systems design in electrochemical nitrate production and other electrocatalytic fields.