Electrodeposition Of Tin And Zinc Catalysts On Copper Substrate For Carbon Dioxide Electrochemical Reduction

The ever-increasing concentration of atmospheric carbon dioxide?CO₂?is the main cause of environmental problems.Reduction of CO₂ into energy-rich fuels and useful chemicals has received considerable attention in recent years as a potential strategy for mitigating carbon dioxide and effectively storing intermittent renewable energy simultaneously.Electrochemical reduction of CO₂ is considered to be an effective way because that the products can be easy control by electric potential,temperature and concentration of electrolyte,electrolyte recycling is convenient,electrolytic cell structure is simple and so on,.However,a large overpotential of reaction,low faradaic efficiency?FE?and energy efficiency,and poor selectivity and stability of catalyst are the main problems of electrochemical reduction of CO₂ at present.Therefore,the preparation of high activity,high selectivity,high stability and low cost electrocatalyst are the key factors for the development of CO₂ electrochemical reduction.In this dissertation,we prepared tin electrode and zinc electrode as catalysts for CO₂electrochemical reduction using low cost tin salt and zinc salt as raw material and copper as substrate.The main contents are as follows:?1?A series of copper foils with different surface roughness were prepared using electrochemical polishing methods.Using these copper foil as the substrate,the tin electrodes with three-dimensional?3D?porous structure were prepared by electrochemical deposition method for the electrochemical reduction of CO₂ into formic acid.The results indicated that the faradaic efficiency of CO₂ to formic acid were dependent on the surface roughness of copper foil that could be controlled by the electropolishing time.The prepared 3D tin electrode on the smoothest Cu foil exhibited the highest FE of 90%,which was 1.6 times that on the original copper foil.Meanwhile,the Sn loss ratio of this electrode in the electrochemical process is the lowest,showing good stability.?2?A series of Zn catalysts with different crystal facet ratios of Zn?002?to Zn?101?were prepared on electrochemically polished Cu foam by electrochemical deposition method with different concentrations of surfactant.The results of CO₂ reduction indicated that Zn?101?crystal facet showed a good electrochemical activity for CO₂ reduction reaction to CO,and Zn?002?crystal facet favored to hydrogen evolution reaction.And the linear relationship between the crystal facet ratio of Zn?101?to Zn?002?and the faradaic efficiency of CO₂RR to CO was revealed.The prepared catalyst with preferentially exposed?101?facet showed greater than 85%faradaic efficiency to syngas at-0.9 V?vs.RHE?in aqueous electrolyte with tunable CO/H₂ ratios ranging from 0.2 to 2.31 that is suitable for the existing industrial systems of syngas process.Meanwhile,the mechanism of electroreduction of CO₂ on Zn electrode was studied by in-situ infrared absorption spectroscopy.The highly selective role of Zn?101?crystal facet in CO₂ reduction into CO was evidenced by density functional theory calculations.