Electrochemical Ammonia Synthesis via NO Reduction on 2D-MOF.

Developing new catalysts that effectively promote electrocatalytic NO reduction (ENOR) is a very important industrial field. A two-dimensional (2D) metal-organic framework (MOF) with hexaaminobenzene (HAB) ligands (TM-HAB MOF, TM=Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Ru, Rh and Pd) as an electrocatalyst for ENOR was systematically explored in this work by means of well-defined density functional theory (DFT) calculations. We predicted the impact of the coordination structure of different MOFs on its catalytic performance and found that the suitable candidates are Co- and Rh-HAB MOFs due to moderate binding strength between NO and substrates. Further calculations indicated that Co-HAB MOF has the best ENOR catalytic activity with a limiting potential of - 0.26 V toward NH3 production at low NO coverage, yet NO reduction to N2 O at high NO coverage was limited due to high limiting potential. The scaling relationship with a good correlation coefficient between several electronic properties and the adsorption Gibbs free energy change of *NO (ΔG*NO ) were found, which implies that ΔG*NO can be used as a simple descriptor for screening out suitable electrocatalysts. This work offers a new paradigm for ENOR toward NH3 production under ambient conditions.