Preparation And Catalytic Properties Of Nanoporous Structures Based On Cu-based Amorphous Alloys

Direct methanol fuel cell?DMFC?,which uses methanol aqueous solution as the fuel source,has excellent features including high energy density,high conversion efficiency,ease of transportation,and low pollution emissions.At present,many Pt-based metal catalysts have been used as the anode catalytic materials of DMFC.However,its commercial application is limited due to its high price.The nanoporous material has a high specific surface area,which makes it an important application in catalytic science.Therefore,in this article nano-porous structure materials are prepared by dealloying Cu-based amorphous alloy ribbons in acid solution.The chemical composition and microstructure of the porous materials were characterized by X-ray diffractometry and microstructure analysis.The influence of the composition of the Cu-based amorphous alloy and the process parameters of the dealloying on the porous structure were analyzed.Cyclic Voltammetry?CV?and Cronoamperometry?CA?method were used to study the electrocatalytic oxidation performance and stability of porous structure materials in alkaline methanol solution.After treated by HCl solution,many cracks distribute on the surface of Cu₃₇Zr₂₈Ni₃₅amorphous alloy the alloy ribbons.The surface of the non-cracked region is unevenly distributed with a small number of small-sized pores,and a large number of agglomerated particles are present in the surface region.After the dealloying in HF solution,a continuous pore structure is formed on the surface of the ribbon.Among the Cu₅₀Zr₃₀Ni₂₀,Cu₄₀Zr₃₀Ni₃₀,and Cu₃₅Zr₃₀Ni₃₅ amorphous alloys,the Cu₄₀Zr₃₀Ni₃₀ sample after dealloyed by HF solution shows the highest electrocatalytic activity(anodic peak current density:258.2 mA cm^-2,presence of 1 M CH₃OH in 1 M KOH solution)toward methanol oxidation.Among the Cu-Ti and Cu-Ti-Ni amorphous alloys,the Cu₆₆Ti₃₀Ni₄ amorphous alloy obtains the optimal porous structure and the best catalytic performance after dealloyed in dilute sulphuric acid solution,and the anodic peak current density of methanol oxidation is 298.2 mA cm^-22 in 1 M KOH solution presence of 1 M CH₃OH.With the increase of corrosion temperature,the dissolution rates of Ti and Ni atoms increase,and the corrosion degree increases at the same time.The diffusion rate of copper atoms increases,resulting in an increase in the pore size of the structure.After dealloyed in H₂SO4 solution,the(Cu_0.66Ti_0.3Ni_0.04)₉₆Ag₄ amorphous ribbon is completely crystallized,consisting of porous copper crystals and a small amount of Ag₂O crystals.The anodic peak current density of methanol oxidation is 325.2 mA cm^-2.The addition of a small amount of Pt increases the corrosion resistance of the alloy,and the surface of(Cu_0.66Ti_0.3Ni_0.04)₉₆Pt₄ amorphous ribbon is evenly distributed with granular material after dealloyed in H₂SO4 solution.The anodic peak current density of methanol oxidation is 159.3mA cm^-2,smller than that without the addition of Pt.