Unveiling selective nitrate reduction to ammonia with CoO nanosheets/TiO nanobelt heterostructure catalyst.

Electrochemical nitrate (NO) reduction reaction (NORR) possesses two-pronged properties for sustainable ammonia (NH) synthesis and mitigating NO contamination in water. However, the sluggish kinetics for the direct eight-electron NO-to-NH conversion makes a formidable challenge to develop efficient electrocatalysts. Herein, we report a heterostructure of CoO nanosheets decorated TiO nanobelt array on titanium plate (CoO@TiO/TP) as an efficient NORR electrocatalyst. Both experimental and density theory calculations reveal that the heterostructure of CoO@TiO establishes a built-in electric field which can optimize the electron migration kinetics, as well as facilitate the adsorption and fixation of NO on the electrode surface, ensuring the selectivity to NH. As expected, the designed CoO@TiO/TP exhibits a remarkable Faradaic efficiency of 93.1 % and a remarkable NH yield as high as 875 μmol h cm, superior to CoO/TP and TiO/TP. Significantly, it also demonstrates strong electrochemical durability.