Applying heteroatom co-doped carbon nanotube for manifesting high performance in the electrochemical reduction of aqueous nitrogen oxide by gold nanoparticles

Electrochemical NO-to-NH₃ under ambient conditions could be a viable alternative having advantages in terms of energy consumption and exhaust gas recycling of NO, replacing a traditional ammonia synthesis method of the Haber–Bosch process. In synthesizing boron (B-) and nitrogen (N-) co-doped carbon nanotube (CNT) based gold (Au) catalysts, B-dopants elevate the conductivity of carbon nanotube by sp² hybridization on graphene and implant B–N domains within the graphene layer, and result in facilitating the embedding amount of Au accompanied by high dispersibility with low particle size. Theoretical density functional theory (DFT) calculations elucidate that the electron cloud transmitted from B-dopant to the active site of Au induces the Lewis acidic site, and the O-distal pathway occurs following a spontaneous reaction. Increment of the electron-deficient B-doping area accompanied by N-defects and B–O edges retains the major valence state of Au as Au^δ+, and suppresses hydrogen evolution reaction (HER) by repulsing the hindrance of H*. This record exhibits the highest faradaic efficiency (FE) of 94.7%, and NH₃ yield rate of 1877.4 μg·h⁻¹·mg_cat⁻¹, which is the optimal yield over energy consumption in the field of the ambient reduction of aqueous NO.