Deposition Of Copper-based Materials On The Surface Of Porous Carbon Electrodes And Its Application To CO₂ Reduction

Electrocatalytic carbon dioxide reduction（CO₂RR）can convert CO₂ into CO and small organic molecules with the help of catalysts,and electric energy can be stored as chemical energy,which provides a feasible scheme for the efficient use of energy and the application of carbon cycle.In this paper,low-cost and expandable porous graphite felt（GF）was used as the carrier to explore the deposition and growth mechanism of copper on the surface of porous carbon electrode,and try to find an effective way to regulate the growth of copper monolayer,so as to improve the catalytic activity and stability of copper modified three-dimensional carbon electrode used in CO₂RR.（1）The influences of organic/inorganic anions in solution were investigated on metal Cu deposited on the surface of graphite felt.The experimental results show that inorganic anions would occupy the defect sites on the surface of graphite felt,and lead to the agglomeration of particles and the stacking thick layer of Cu（0）.Meanwhile,organic anions can complex with Cu ions,and slow down the bulk deposition of metal Cu（0）on graphite felt and promote the formation of univalent Cu（I）,especially under a small overpotential（condition of diffusion control）.The effective combination of Cu（0）and Cu（I）could form multivalent Cu on the surface of graphite felt with high specific surface area.It could enhance the activity and stability of Cu-modified graphite felt as reaction electrode and make it possible to reduce CO₂efficiently.（2）Copper-modified graphite felt electrodes（GF-Cu/Cu₂O）were prepared and applied to the electrocatalytic carbon dioxide reduction reaction（CO₂RR）.The experimental results show that the Cu/Cu₂O modified graphite felts prepared under a small overpotential have high electrocatalytic activity and large corrosion resistance.The large reduction current density appears during the potential range of-0.7～-0.9V vs.Ag/Ag Cl in 0.5 mol/L Na HCO₃solution.Ethanol molecules have been identified from the reduction products.It also shows the stable current density for long-term constant voltage operation,which was more than 95%during the reaction lasted during 0.36 to 5 hours.For Cu/Cu₂O sub-monolayer structure on porous graphite felt,it indicated that the more defects were introduced to improve electrode activity through providing reaction sites for CO₂.The strong bond between C and Cu atoms enhances electrode stability and corrosion resistance.This work also confirmed that metal-modified carbon electrodes can synergistically improve the CO₂RR process.