| Electricatalytic CO2 reduction(CO2RR)to organic fuels is a promising approach to reduce the CO2 concentration in the atmosphere,and to mitigate the"green" house effect,as well as realize energy recycling through CO2 utilization.It is also a vital step to the establishment of carbon-balancing economy.CO2RR refers to multiple electron and proton transportation in gas-liquid-solid three-phase interface,which brings about new requirements for the design of electrode structures.Cu is the only metal catalyst that has multiple reaction routes and reduction products for CO2RR with selectivity towards various C1 and C2+products.Thus,it is important but difficult to optimize the catalytic selectivity.To date,tremendous efforts have been paid to the influence of catalyst size,composition,crystal orientation and oxide state on the CO2RR performance;however,the activity and selectivity are still not satisfactory because uncertainty still remains for the mechanism investigation.At the same time,very few study focuses on the local properties of the electrode/electrolyte interface,and mass transfer kinetics of CO2 at the gas-liquid-solid three-phase interface.Therefore,it is of great significance to further enhance the CO2RR efficiency through deep understand of the CO2RR kinetics,development of efficient and stable catalysts,and design of high performance mass diffusion electrode.Based on this,this work focuses on the development of effiecient catalysts and electrode for CO2RR,mainly emphasizing on two aspects:one is the regulation of electrode/electrolyte interface;the other is tuning of the atomic structure and electronic structure on the catalyst surface.In the first part,CO2 diffusion pathways,electrons and ions transportation behaviors in the electrode/electrolyte were studied to reveal the mass and electron transportation dynamics,as well as the structure-property relationship between the micromacro electrode interface and the CO2 reduction pathway.In the second part,the crystal face and nanoparticles size were reconstructed via wet oxidation and in-situ reduction;Cu2S-Cu2O supported on Cu foil was synthetized via cyclic voltammetry method,and metallic Cu composed of strain was obtainedsubsequent electrochemical reduction,leading to optimized adsorption energies of CO2RR intermediate.viaThe detailed research are as follows:(1)Electrode/electrolyte interface construction via quaternary ammonium cation surfactant to alter CO2RR pathway and regulate CO2 molecules diffusion behaviors.Interaction between Cu and N atom in the cation surfactant influences the electronic property of the catalyt surface,and in turn tunes the pathway of CO2RR;Interaction between CO2 molecules and hydrophobic side of the cation surfactant accumulates CO2 molecules and increase CO2 coverage at the electrode/electrolyte interface.This strategy was applicable to several kinds of electrodes,such as Cu,Sn and Zn foil,suggesting this was a general method.This strategy provides a new route in the development of highly active and selective electrocatalyts for other gas consumption reaction systems like hydrogen oxidation reaction(HOR),oxygen reduction reaction(ORR),nitrogen reduction reaction(NRR)etc.(2)Surface reconstruction of crystal face and nanoparticles size via wet oxidation and in-situ reduction for CO2 electroreduction to methane.The selectivity of methane highly depends on the relative adsorption strength of*CO and*H.Therefore,wet oxidation and in-situ cyclic voltammetry reduction was utilized to adjust the crystal face and nanor articles size.High proportion of Cu(111)orientation was realized and the nanoparticle sieze was controlled.The obtained reconstruction copper catalyst suppressed HER and exhibit high methane selectivity.(3)Surface reordering copper catalyst for CO2 electroreduction to ethylene.The selectivity of Cu metal is poor and always suffer from serious hydrogen evolution reaction.In the second part,sulfur and oxygen doping was utilized to adjust the coordination environment of copper atoms;tensile strain was introduced into the copper crystal through subsequent in-situ electrochemical reduction of the Cu2O/Cu2S presursors,leading to optimized adsorption energies towards*CO and*COOC intermediates.High proportion of Cu(100)orientation was realized by control of experimental parameters.The obtained reordering copper catalyst suppressed HER and exhibit high C2+selectivity,especially for ethylene products. |
