Boosted charge and proton transfer over ternary Co/Co3O4/CoB for electrochemical nitric oxide reduction to ammonia

Abstract

The electrochemical nitric oxide reduction reaction (NORR) holds a great potential for removing environmental pollutant NO and meanwhile generating high value-added ammonia (NH₃). Herein, we tactfully design and synthesize a ternary Co/Co₃O₄/CoB heterostructure that displays a high NH₃ Faradaic efficiency of 98.8% in NORR with an NH₃ yield rate of 462.18 µmol cm⁻² h⁻¹ (2.31 mol h⁻¹ g_cat⁻¹) at −0.5 V versus reversible hydrogen electrode, outperforming most of the reported NORR electrocatalysts to date. The superior NORR performance is attributed to the enhanced charge and proton transfer over the ternary Co/Co₃O₄/CoB heterostructure. The charge transfer between CoB and Co/Co₃O₄ yields electron-deficient Co and electron-rich Co₃O₄. The electron-deficient Co sites boost H₂O dissociation to generate *H while the electron-rich low-coordination Co₃O₄ sites promote NO adsorption. The *H formed on electron-deficient Co sites is more favorable to transfer to electron-rich Co₃O₄ sites adsorbed with NO, facilitating the selective hydrogenation of NO. This study paves the way for designing and developing highly efficient electrocatalysts for electrochemical reduction of NO to NH₃.