Promoting N2 electroreduction into NH3 over porous carbon by introducing oxygen-containing groups

The electroreduction of N 2 into NH 3 is regarded as an environmentally-benign and sustainable strategy for artificial N 2 fixation at ambient conditions. Nevertheless, most of the catalysts suffer from low yield rate and Faradaic efficiency in this process. In this work, we developed a porous carbon with oxygen-containing groups (denoted as oxidized carbon) to promote N 2 electroreduction into NH 3 . At −0.3 V versus reversible hydrogen electrode ( vs RHE), oxidized carbon achieves a high Faradaic efficiency of 16.50% for NH 3 , which is 3.3 times as high as porous carbon (denoted as pristine carbon) (5.07%). Notably, the yield rate of oxidized carbon for NH 3 reaches 32.20 μg NH3 mg −1 cat. h −1 , higher than that (14.52 μg NH3 mg −1 cat. h −1 ) of pristine carbon at −0.5 V vs RHE. Mechanistic studies revealed that the introduction of oxygen-containing groups into porous carbon effectively decreased the energy barrier of hydrogenation and suppressed the competing hydrogen evolution reaction, thereby promoting N 2 electroreduction to NH 3 .