Nitrogen-Defective Polymeric Carbon Nitride Nanolayer Enabled Efficient Electrocatalytic Nitrogen Reduction with High Faradaic Efficiency

Identifying highly selective catalysts and accurately measuring NH 3 yield without false-positives from contaminations remain two challenges in electrochemical nitrogen reduction reaction (NRR). Here, we report N-defective carbon nitride grown on carbon paper (CN/C) as a highly selective electrocatalyst. The NH 3 yield was determined reliably by the slope of m NH3 -time plot rather than averaging the accumulated amount over time. Results showed the as-synthesized CN/C 600 (synthesized at 600 °C) with a higher density of C=N–C N 2C vacancies achieved an NH 3 production of 2.9 μg mg cat. –1 h –1 at −0.3 V (versus RHE), ∼5.7-fold higher than CN/C 500 . The Faradaic efficiency for CN/C 600 is among the highest of 62.1%, 33.9%, and 16.8% at −0.1 V, −0.2 V, and −0.3 V, respectively. The NH 3 production was verified by isotope 15 N 2 experiments. Further increase of N-defects on CN/C 600 using plasma etching led to higher NH 3 yield than comparably larger current, pointing to N-defects sites for promoting NRR.