Defective TiO2−x for High‐Performance Electrocatalytic NO Reduction toward Ambient NH3 Production

Abstract Synthesis of green ammonia (NH 3 ) via electrolysis of nitric oxide (NO) is extraordinarily sustainable, but multielectron/proton‐involved hydrogenation steps as well as low concentrations of NO can lead to poor activities and selectivities of electrocatalysts. Herein, it is reported that oxygen‐defective TiO 2 nanoarray supported on Ti plate (TiO 2− x /TP) behaves as an efficient catalyst for NO reduction to NH 3 . In 0.2 m phosphate‐buffered electrolyte, such TiO 2− x /TP shows competitive electrocatalytic NH 3 synthesis activity with a maximum NH 3 yield of 1233.2 µg h −1 cm −2 and Faradaic efficiency of 92.5%. Density functional theory calculations further thermodynamically faster NO deoxygenation and protonation processes on TiO 2− x (101) compared to perfect TiO 2 (101). And the low energy barrier of 0.7 eV on TiO 2− x (101) for the potential‐determining step further highlights the greatly improved intrinsic activity. In addition, a Zn‐NO battery is fabricated with TiO 2− x /TP and Zn plate to obtain an NH 3 yield of 241.7 µg h −1 cm −2 while providing a peak power density of 0.84 mW cm −2 .