Study On The Fabrication Of 3D Printed Hierarchical Porous Bimetal And Its Electrocatalytic CO₂ Reduction Performance

Carbon dioxide is one of the main causes of global warming,and electrocatalytic reduction of carbon dioxide provides a technical means with good application prospects for carbon capture.In the carbon dioxide reduction process,hydrogen reduction（HER）is unavoidable.Therefore,synthesis gas（H₂+CO）is a target product of carbon dioxide reduction with high economic benefits.Traditional CO₂reduction electrocatalytic materials have disadvantages such as complex preparation process,small electrode area,and poor stability,making it difficult to realize large-scale production and application.Therefore,there is an urgent need to develop catalyst materials and preparation processes that can solve the above problems.Selective Laser Melting（SLM）3D printed electrodes provide a unique idea for the preparation of carbon dioxide electrocatalysts.Through SLM technology,catalyzer with millimeter or micrometer-level pores morphology can be efficiently prepared,and the preparation of nanoporous structures by dealloying is a technological means to increase the active area of the catalyst surface on the nanometer scale.In this paper,by combining 3D printing technology and dealloying,a three-dimensional hierarchical nanoporous catalyst with high stability and high catalytic activity was prepared,its structure and electroreduction carbon dioxide performance were systematically studied.This article first studied the SLM 3D printing preparation technology and dealloying process of Zr₄₅Cu_39.27Al₇Ag_8.73amorphous alloy.The study found that the time and potential of electrochemical dealloying significantly affected the structure and composition of nanoporous,a lower voltage can lead to incomplete dealloying,and the higher voltage will cause clusters to form on the nanoporous surface,resulting in a decrease in surface active area.Based on the structural characterization and electrocatalytic performance test results,the dealloying process parameters with the most uniform surface,the highest synthesis gas Faraday efficiency（92.2%）and the largest synthesis gas control range（0～3）were selected.The voltage was 0.1 V,dealloying time is 30 minutes,in 0.05 M HF solution.The influence of chemical composition on CO₂reduction performance of three-dimensional hierarchical porous metal was studied.By designing precursor composition(Zr₄₅Cu_39.27Al₇Ag_8.73,Zr₅₅Cu₃₀Ni₅Al₁₀,respectively),nanoporous copper silver（NP-Cu Ag）and nanoporous copper（NP-Cu）were obtained.The study found that the highest synthesis gas Faraday efficiency of NP-Cu is only 63.2%,which was far lower than92.2%of NP-Cu Ag,and the yield of NP-Cu Ag（86μmol/cm²/h）was also much higher than that of NP-Cu（43μmol/cm²/h）.XPS and AC impedance test analysis showed that the introduction of Ag changed the energy band structure of Cu and enhanced the conductivity of the three-dimensional porous catalyst;and the hydrogen adsorption capacity of NP-Cu Ag in alkaline solution was lower than that of NP-Cu,thus inhibiting HER process,leading to NP-Cu Ag’s excellent catalytic performance.This chapter reveals the influence mechanism of alloying on catalytic performance through the performance difference of single and double metal catalysts,and provides guidance for composition design.The effect of porous morphology on the catalytic performance of three-dimensional hierarchical porous metals was studied.Using the advantages of 3D printing,three-dimensional layered nanoporous copper-silver electrodes with different shapes were prepared.The study found that the honeycomb sample has the best catalytic performance,reaching a total Faraday efficiency of 96.1%and a synthesis gas of 142μmol/cm²/h yield.More importantly,compared with the two-dimensional amorphous ribbon,the honeycomb sample exhibited an ultra-long catalytic stability of 140 h.This is because the catalyst has a three-scale porous structure of millimeter-micro-nano.The millimeter porosity promotes the growth of bubbles and desorption.The microporosity releases the stress in the dealloying process to make the nanoporous layer and the substrate more stable.The nanoporosity increases the active area of the catalyst,and the three work together to achieve the excellent performance of the honeycomb sample.The effect of the microscopic morphology on the catalytic performance of the sample was further studied.The nanoporous Cu Ag was cyclically modified in KOH and KHCO₃solutions.It was found that both methods would affect the structure and composition of the sample surface,and the yield reached 172μmol/cm²/h and 156μmol/cm²/h,compared with untreated samples increased by 95%and 77%.This chapter changes the catalytic performance of the catalyst by adjusting the morphology at different scale levels,and provides a new idea for the preparation and modification of the catalyst.