In Situ Synthesis of Cu<sub>x</sub>O/N Doped Graphdiyne with Pyridine N Configuration for Ammonia Production via Nitrate Reduction
Jian Li, Roberto Valenza, Sophia Haussener
Abstract
Abstract Electroreduction of nitrate to ammonia provides an interesting pathway for wastewater treatment and valorization. Cu‐based catalysts are active for the conversion of NO 3 − to NO 2 − but suffer from an inefficient hydrogenation process of NO 2 − . Herein, Cu x O/N‐doped graphdiyne (Cu x O/N‐GDY) with pyridine N configuration are in situ prepared in one pot. Benefiting from the synergistic effect of pyridinic N in GDY and Cu x O, the prepared Cu x O/N‐GDY tested in a commercial H‐cell achieved a faradaic efficiency of 85% toward NH 3 at ‐0.5 V versus RHE with a production rate of 340 µmol h −1 mg cat −1 in 0.1 M KNO 3 . When integrating the Cu x O/N‐GDY in an anion exchange membrane flow electrolyzer, a maximum Faradaic efficiency of 89% is achieved at a voltage of 2.3 V and the production rate is 1680 µmol h −1 mg cat −1 at 3.3 V in 0.1 M KNO 3 at room temperature. Operation at 40 °C further promoted the overall reaction kinetics of NO 3 − to NH 3 , but penalized its selectivity with respect to hydrogen evolution reaction. The high selectivity and production rate in this device configuration demonstrate its potential for industrial application.