Preparation Of Ni-and Cu-based Electrocatalysts For High-efficiency CO₂ Reduction

The increasing consumption of fossil fuels not only intensifies energy depletion,but also accompanied by a large amount of carbon dioxide（CO₂）emission,which destroys the carbon cycle in nature and induces a series of environmental problems such as ecological imbalance,global warming and glacier melting,Electrochemical CO₂reduction reaction（ECO₂RR）is a promising and sustainable route to producing hydrocarbons and alcohols.However,catalysts in the ECO₂RR process still face many challenges,such as poor stability,low activity and selectivity,high overpotential,and low Faraday efficiency.Therefore,the theoretical design and controlled synthesis of high-efficiency ECO₂RR catalysts are scientific problems that need to be solved urgentlyIn this paper,Ni and Cu-base catalysts were taken as the research object and aims to synthesize efficient and stable composite catalyst materials.The geometrical and electronic structures of materials were regulated through morphology engineering,and the performance of ECO₂RR was investigated.The structure-activity relationship between catalyst structure and catalytic performance was mainly investigated,providing new ideas and a basis for the development of high-performance and high-stability catalysts.The specific research contents are as follows:1.A dual chainmail-bearing nickel-based catalyst was prepared by solvothermal-evaporation-calcination method,the in-situ encapsulation of N-doped carbon layers（NC）and nanotubes（NCNT）provides dual protection for the metal core（Ni@NC@NCNT）.It delivered a CO Faradaic efficiency of 94.1%and current density of 48.0 m A cm^-2at-0.75 V and-1.10 V respectively.More importantly,the current density and CO Faraday efficiency of continuous electrolysis for 43 h show almost no decay.This excellent high catalytic activity and stability due to its unique double-chain structure,on the hand,it can protect the metal core from the corrosion of the electrolyte and improve the mechanical strength of catalysts;on the other hand,the charge can be effectively transferred from the metal nanoparticles to the carbon layer through the Ni-O and Ni-N chemical bonds,which improves the activity of the catalyst.2.One-dimensional heterogeneous molecular catalyst for CH₃SCu nanowires with the unique structure were prepared by a simple one-step hydrothermal method,the HCOOH Faradaic efficiency of 70.3%and current density of 23.1 m A cm^-2at-0.95 V and-1.35 V respectively.The Faraday efficiency retention rate of HCOOH was 97.9%after 15.5h continuous electrolysis.According to the kinetics and reaction order analysis,the rate determining step of CH₃SCu nanowires is CO₂^·-through the initial electron transfer or the formation of^*HCOOH by proton binding.The concentration dependence of KHCO₃ in the reaction process is close to zero-order,indicating that the protons in electrolyte HCO₃^-do not participate in the determination step in the electrolysis process.3.The fractional structure CuO nanosheet catalyst derived from Cu-INA complex was prepared by solvothermal-calcination.It delivered a C₂₊Faradaic efficiency of 64.0%and current density of 48.7 m A cm^-2at-1.3 V and-1.7 V respectively.It is far better than that of the control samples Cu and Cu₂O.