Constructing Co@TiO2 Nanoarray Heterostructure with Schottky Contact for Selective Electrocatalytic Nitrate Reduction to Ammonia

Abstract Electrochemical nitrate (NO 3 − ) reduction reaction (NO 3 − RR) is a potential sustainable route for large‐scale ambient ammonia (NH 3 ) synthesis and regulating the nitrogen cycle. However, as this reaction involves multi‐electron transfer steps, it urgently needs efficient electrocatalysts on promoting NH 3 selectivity. Herein, a rational design of Co nanoparticles anchored on TiO 2 nanobelt array on titanium plate (Co@TiO 2 /TP) is presented as a high‐efficiency electrocatalyst for NO 3 − RR. Density theory calculations demonstrate that the constructed Schottky heterostructures coupling metallic Co with semiconductor TiO 2 develop a built‐in electric field, which can accelerate the rate determining step and facilitate NO 3 − adsorption, ensuring the selective conversion to NH 3 . Expectantly, the Co@TiO 2 /TP electrocatalyst attains an excellent Faradaic efficiency of 96.7% and a high NH 3 yield of 800.0 µmol h −1 cm −2 under neutral solution. More importantly, Co@TiO 2 /TP heterostructure catalyst also presents a remarkable stability in 50‐h electrolysis test.