Dual-metal sites in MOF synergistic boosting NH ₃ production under low-nitrate concentration

The electrocatalytic conversion of nitrate to ammonia has made significant progress as a promising strategy for removing NO₃^- and producing NH₃. However, there is a lack of an efficient electrocatalyst to achieve highly selective NH₃ synthesis under low concentration NO₃^- conditions. In this study, we design and synthesize a bimetallic copper-containing MOF (CuInL₄, L = 4-4-(Pyridin-4yl) benzoic acid), named InCu-MOF, which possesses 2-fold interpenetrating structure and high-density catalytic sites. InCu-MOF is the first MOF catalyst applied to NH₃ synthesis at low NO₃^- concentration. Benefiting from the regulation of electronic properties and synergistic catalytic effects of two metal active sites, InCu-MOF exhibits high catalytic activity for the low concentration of NO₃RR for the first time. At a potential of -1.0 V (vs. RHE), InCu-MOF achieves NH₃ faradaic efficiency (FE) of 82% and yield rate of 892 µg h^-1mg_cat^-1, which FE is 2.6-fold and yield rate are 8.1-fold higher than that of In-MOF. The design and synthesis of this interpenetrating bimetallic MOF provides an idea for the construction of an efficient catalyst at low NO₃^- concentrations.