Ultra-small Cu nanoparticles embedded in N-doped carbon arrays for electrocatalytic CO2 reduction reaction in dimethylformamide

摘要

The development of heterogeneous catalysts with a well-defined micro structure to promote their activity and stability for electrocatalytic CO2 reduction has been shown to be a promising strategy.In this work,Cu nanoparticles (～ 4 nm in diameter) embedded in N-doped carbon (Cu@NC) arrays were fabricated by thermal decomposition of copper tetracyanoquinodimethane (CuTCNQ) under N2.Compared to polycrystalline copper electrodes,the Cu@NC arrays provide a significantly improved number of catalytically active sites.This resulted in a 0.7 V positive shift in onset potential,producing a catalytic current density an order magnitude larger at a potential of-2.7 V vs.Fc/Fc+ (Fc =ferrocene) in dimethylformamide (DMF).By controlling the water content in the DMF solvent,the CO2 reduction product distribution can be tuned.Under optimal conditions (0.5 vol.％ water),64％ HCOO-,20％ CO,and 13％ H2 were obtained.The Cu@NC arrays exhibited excellent catalytic stability with only a 0.5％ decrease in the steady-state catalytic current during 6 h of electrolysis.The three-dimensional (3D) array structure of the Cu@NC was demonstrated to be effective for improving the catalytic activity of copper based catalysts while maintaining long-term catalytic stability.