Synergy of Diatomic CuSb-HAB Catalyst with Methanol Oxidation to Promote Formamide Electrosynthesis

Abstract

Electrochemical co-reduction of CO2 and NOx- to formamide (ECNF) provides a promising pathway for sustainable formamide synthesis, yet its electrocatalytic activity and selectivity remain unsatisfactory. Herein, a CuSb-HAB metal-organic framework catalyst, featuring Cu-Sb diatomic sites within a conductive hexaaminobenzene (HAB) matrix, is developed for highly efficient formamide synthesis from co-electrolysis of CO2 and NO2-. Theoretical calculations and in situ spectroscopic characterizations unravel the essential role of d-p hybridized Cu-Sb diatomic sites in synergistically stabilizing two key intermediates (*CHO and *NH2) and promoting their C-N coupling for formamide synthesis. Notably, a two-electrode MEA electrolyzer integrating cathodic ECNF with anodic methanol oxidation delivers the outstanding Faradaic efficiency of 61.21% and formamide yield rates of 777.9 mmol h-1 g-1, together with the exceptional electrolysis durability for over 200 h, representing one of the highest reported values.