Highly selective electroreduction of N2 and CO2 to urea over artificial frustrated Lewis pairs

Abstract

The simultaneous electrocatalytic conversion of N₂ and CO₂ into value-added urea is highly anticipated but suffers from the predicament of the poor chemisorption, activation, and coupling activity of reactant molecules. Herein, unique frustrated Lewis pairs (FLPs) were precisely designed in flower-like nickel borate [Ni₃(BO₃)₂], where the surface hydroxyl and neighboring Ni site serve as a Lewis base and acid, respectively. Comprehensive investigations endorsed that the Lewis basic and acidic sites in FLPs acted synergistically in the targeted capture of inert CO₂ and N₂ by orbital interaction. Subsequently, the bonding and antibonding orbitals of the inert gas interacted with the empty orbitals of the Lewis acid and nonbonding orbitals of the Lewis base, respectively, achieving molecule activation by FLPs. Afterward, the *NN* and CO intermediates underwent electrocatalytic C–N coupling by the σ orbital carbonylation strategy to produce *NCON* precursors. Thus, the prepared Ni₃(BO₃)₂-150 nanocrystal delivered the record-highest urea yield rate of 9.70 mmol h⁻¹ g_cat⁻¹ and a Faradaic efficiency of 20.36% at −0.5 V vs. RHE.