Application Of Copper Nanowires Electrode In Electrocatalytic Reduction Of Carbon Dioxide

Carbon dioxide reduction(CO2RR),as an emerging technique,inspired a new direction for humans to solve both energy and environmental related issues in recent years.Cu has its practical application value with the wide product distribution and in-depth carbon dioxide electro-reduction ability.However,problems such as high overpotential,uncontrollable product selectivity,and deactivation of catalysts which limited their further development.In the past decades,numerous Cu nano materials have devoted to increasing performance of the electrocatalytic reduction of CO2 by reducing operating overpotential and increasing current density.However,ultrahigh hydrogen evolution activity and poor product regulation have not been effectively solved so far.In addition,the in-depth reduction capability has not been fully exploited on Cu-based catalysts.In contrast to the tremendous progresses in exploring catalysts,the interface wettability and electrode-architecture construction received very limited attention.Herein,we carried out the following work using Cu nanowires as the starting materials to solve the abovementioned problems.1)A new type of grain boundary riched Cu nanowires with uniform size,high aspect ratio and rough surface was fabricated by a simple liquid phase reduction method.Operating overpotential of the polycrystalline Cu materials was obviously reduced and catalytic activity was enhanced due to the structural advantages of one-dimensional materials.Subsquently polytetrafluoroethylene(PTFE)modification rendered the Cu nanowires with superaerophilicity and superhydrophobicity.The as constructed underwater gas diffusion pathway from aerophilicity accelerated the mass transfer of carbon dioxide which improved products selectivity and controllability,the faradic efficiency(FE)of CO was about 71%at-0.4 V vs.RHE and such high selectivity could be switched to HCOOH(FE?68%)at-0.6 V vs.RHE.While,hydrogen evolution activity was effectively suppressed,which enhanced the selectivity of CO2 reduction up to 78%.In addition,the constructed gas/ion diffusion layer optimized the gas and ion diffusion paths which enhanced the stability of Cu nanowires.2)Highly density Cu nanowires array was fabricated on Cu foil substrate by chemical etching,high temperature dehydration and electroreduction,respectively.The high specific surface area derived from nanoarray structure enhanced the catalytic activity of Cu nanowires,while a local high pH effect derived from highly density nanowires enhanced the in-depth reduction ability of Cu nanowires.According,selectivity of C2 products have been significantly improved(-1.1V,RHE,FE?50%)and a considerable C3 product isopropanol has been obtained(-1.1V,RHE,FE?13%).Subsequently polyethyleneimine(PEI)modification enhanced the CO2 enrichment and capture capability of Cu nanowires array,which obliviously reduced the overpotential of generating isopropanol(200mV)and improved the selectivity of ethylene,ethanol and isopropanol to some extent.