Abstract:

Transition metal-nitrogen co-doped carbon-based catalysts have attracted widely attention in electrocatalytic CO₂ reduction reaction（CO₂RR）.To solve the problems of catalytic activity and selectivity of catalysts,two kinds of Ni-N co-do-ped porous carbon-based catalysts were prepared by using triethylenediamine,a small molecule complex,formed by the coor-dination reaction between ethylenediamine and nickel nitrate and hydrophilic GO and hydrophobic carbon black were select-ed as the support,respectively.The existing forms of nickel species in different processing stages were discussed by X-ray diffraction and transmission electron microscopy.The CO₂RR performance showed that the CO current density had been enhanced when the catalyst with different metal loadings on the same carbon support was pickled to remove nickel nanoparticles,which indicated that the nickel species in high dispersion were beneficial to the electrocatalytic reduction of CO₂.At the potential of -0.8 V(vs.RHE),the catalysts with different carbon supports reached a CO Faradic efficiency of 90%.Compared with hydrophilic carbon materials as supports,hydrophobic carbon materials as supports had higher carbon monoxide partial current density,which indicated that hydrophobic carbon supports were conducive to the loading and dispersion of transition metal complexes in the framework of the support,and then inhibited the loss of active substances in the subsequent treatment process,so as to obtain high activity Ni-N co-doped carbon based electrocatalysts.

Key words: CO₂ electroreduction, carbon-based electrocatalysts, Ni-N co-doped carbon materials, complex, hydrophobicity