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

Abstract

AbstractElectrochemical nitrate (NO3−) reduction reaction (NO3−RR) is a potential sustainable route for large‐scale ambient ammonia (NH3) synthesis and regulating the nitrogen cycle. However, as this reaction involves multi‐electron transfer steps, it urgently needs efficient electrocatalysts on promoting NH3 selectivity. Herein, a rational design of Co nanoparticles anchored on TiO2 nanobelt array on titanium plate (Co@TiO2/TP) is presented as a high‐efficiency electrocatalyst for NO3−RR. Density theory calculations demonstrate that the constructed Schottky heterostructures coupling metallic Co with semiconductor TiO2 develop a built‐in electric field, which can accelerate the rate determining step and facilitate NO3− adsorption, ensuring the selective conversion to NH3. Expectantly, the Co@TiO2/TP electrocatalyst attains an excellent Faradaic efficiency of 96.7% and a high NH3 yield of 800.0 µmol h−1 cm−2 under neutral solution. More importantly, Co@TiO2/TP heterostructure catalyst also presents a remarkable stability in 50‐h electrolysis test.