High-Density Atomically Dispersed CuSn Bimetallic Catalyst for Efficient N₂-Selective Electrocatalytic...

Electrocatalytic denitrification (ECDN) for reduction of NO₃ ^- to N₂ is an effective and environmentally benign strategy for nitrogen-neutral cycle, but N₂ selectivity is poor due to undesirable adsorption of nitrogen oxide intermediates and kinetic sluggishness of N-N coupling. In this study, triggering of p-d orbital hybridization is reported on high-density V-shaped atomically dispersed bimetallic electrocatalyst (CuSn-NC) with two Cu-N₃ terminals and one Sn-N₂ tip for stabilizing the key intermediates essential for N₂-selective ECDN. Results reveal that ≈22.3 wt.% metal-loading bimetallic single-atom CuSn-NC electrocatalyst can achieve 94.1% NO₃ ^- removal with N₂ selectivity as high as 81.7%. A combination of operando measurements and theoretical calculations further verify the p-d orbital hybridization between p-block stannum (Sn) and d-block copper (Cu) in CuSn dual atom sites, which the resultant rate-determining step of ^*NO₃ to ^*NO₂ and selectivity-determining step of N-N coupling are accelerated by optimizing the binding of intermediates on Cu-N₃ and Sn-N₂ tip sites synergistically. This study provides the proof-of-concept demonstration of designing a bimetallic single-atom electrocatalyst for highly N₂-selective ECDN, which offers a promising approach to nitrogen neutrality.