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

The electroreduction of N-2 into NH3 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 NH3. At-0.3 V versus reversible hydrogen electrode (vs RHE), oxidized carbon achieves a high Faradaic efficiency of 16.50% for NH3, which is 3.3 times as high as porous carbon (denoted as pristine carbon) (5.07%). Notably, the yield rate of oxidized carbon for NH3 reaches 32.20 mu gNH(3)mg(-1)cat. h(-1), higher than that (14.52 mu gNH(3) mg(cat.)(-1) 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 NH3.

Automated summary

In this study, a porous carbon material with oxygen-containing groups was developed to enhance the yield rate and Faradaic efficiency of nitrogen electroreduction to ammonia. The introduction of oxygen-containing groups effectively lowered the energy barrier of hydrogenation and suppressed the competing hydrogen evolution reaction, thereby promoting nitrogen electroreduction to ammonia.