Ni doping enabled improvement in electrocatalytic nitrite-to-ammonia conversion over TiO2 nanoribbon

Electrochemical nitrite (NO2−) reduction can produce value-added ammonia (NH3) and simultaneously eliminate NO2− pollutants in surface water and underground water. However, the complicated six-electron NO2− reduction reaction (NO2RR) needs efficient electrocatalysts with high selectivity. Herein, we report that Ni-doped TiO2 nanoribbon array on titanium plate (Ni–TiO2/TP) acts as a high-active NO2RR electrocatalyst with a large NH3 yield of 380.27 μmol/h/cm2 and a high Faradaic efficiency of 94.89%, superior to TiO2/TP. Density functional theory calculations reveal that Ni doping can enhance the intrinsic electrical conductivity and optimize the adsorptive free energy of intermediates for high NO2−-to-NH3 selectivity.