Conductive Metal-covalent Organic Frameworks as Novel Catalytic Platform for Reduction of Nitrate to Ammonia

With their abundant metal sites, ordered porous structure and great conductivity, conductive metal-organic frameworks display many excellent single-atom electrocatalytic activities, superior to conventional inorganic nanostructure. However, their electrochemical application is greatly limited by the fragile coordinated frameworks. Here, we describe a metal-covalent organic frameworks (MCOFs) strategy to construct nitrate reduction (RNA) catalyst using M₃∙HATN as the subgroup. Assisted by salt-template, M-HATN-COFs with abundant metal sites (M at% ≈ 12.5 %) are achieved by a one-step coordination-condensation approach. More importantly, the M-HATN-COFs provide a reasonable platform for studying of metal-atom catalytic mechanism, surpassing the current inorganic structures. The Mo-HATN-COFs exhibit outstanding electrocatalytic properties with a high ammonia yield rate (8.52 mg h⁻¹cm⁻²), FE (91.3 %) and stability for RNA reaction. As the first work of MCOFs for electrochemical NRA, the M-HATN-COFs strategy will innovate the design concept of next-generation catalyst and catalytic mechanism of single-metal-atom.