Defective TiO_{2- x} for High-Performance Electrocatalytic NO Reduction toward Ambient NH₃ Production

Synthesis of green ammonia (NH₃ ) 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 TiO₂ nanoarray supported on Ti plate (TiO_{2- x} /TP) behaves as an efficient catalyst for NO reduction to NH₃ . In 0.2 m phosphate-buffered electrolyte, such TiO_{2- x} /TP shows competitive electrocatalytic NH₃ synthesis activity with a maximum NH₃ 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 TiO₂ (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 NH₃ yield of 241.7 µg h^-1  cm^-2 while providing a peak power density of 0.84 mW cm^-2 .