Theoretical insights of nickel-based dual-metal atoms supported on C_(2)N sheets for urea electrooxidationOA

The electrocatalytic urea oxidation reaction(UOR)enables energy-saving hydrogen production and waste degradation but requires efficient catalysts due to its complex,sluggish 6-electron transfer mechanism.In this study,we designed a series of stable 3d transition metal heterometal atom pairs(TMNi,TM refers to Sc,Ti,V,Cr,Mn,Fe,Co,Ni,Cu,or Zn)supported on the C_(2)N substrate as UOR catalysts,systematically investigating their potential to enhance the activity of Ni_(2)/C_(2)N.Among these,CrNi/C_(2)N displayed a superior capability to lower the limiting potential of the UOR compared to CuNi/C_(2)N andNi/C_(2)N.The enhanced catalytic CrNi/C_(2)N system primarily stems from the stronger TM–Ni interactions,notable differences in charge distribution,more localized electronic states,and a higher d-band center associated with CrNi/C_(2)N relative to CuNi/C_(2)N and Ni_(2)/C_(2)N.These attributes not only ensure the stability of the well-dispersed CrNi pairs on C_(2)N but also amplify the ability of the active center to adsorb and activate reaction intermediates.Moreover,CrNi/C_(2)N demonstrates good selectivity for the UOR by exhibiting reduced susceptibility to forming NO_(2)by-products and undergoing the competing oxygen evolution reaction.This theoretically driven work identifies CrNi/C_(2)N as the top-performing UOR dual-metal-atom catalysts,combining 0.99 V limiting potential with selective N_(2)generation through electronic structure modulation,offering guidance for advanced catalyst design through the strategic use of transition metal heterometal atom pairs.