Interfacial Defect Engineering Triggered by Single Atom Doping for Highly Efficient Electrocatalytic Nitrate Reduction to Ammonia

Electrochemical reduction of nitrate (NO3RR), a widespread water pollutant, to high-valued ammonia is encouraging for sustainable artificial nutrient recycling and environmental-friendly pollution management. However, the limited available catalytic active sites and competitive hydrogen evolution make the catalytic performance still unsatisfactory. In this work, interfacial defect engineering via single atom doping was conducted to achieve highly efficient electrocatalytic NO3RR. Upon introduction of isolated Fe atoms, abundant oxygen vacancies are generated over atomic interface of TiO2, and the induced charge redistribution triggers the formation of considerable active sites for nitrate reduction, which plays a crucial role in inhibiting the proton reduction and promoting the adsorption and activation of nitrate. As expected, single atom Fe modified TiO2 exhibits a maximum ammonia yield rate of 137.3 mg h-1 mgcat.-1 and a Faradaic efficiency of 92.3% at -1.4 V (vs RHE), which are among the best of all the reported values yet. This work provides valuable insights into the exploration of highly efficient electrocatalysts toward nitrate reduction through the heteroatom doping and defect engineering over atomic interface.