Study On The Dealloying And Product Degradation Of Cu-Al-Ti Alloy

In recent years,the advanced oxidation process has gradually become a method for treating organic pollutants in water,including photocatalytic and sonocatalytic techniques.They are not only green and energy-saving,but also efficient and practical.Nano-porous copper and its copper-based semiconductor materials have been considered as good photo(sono)catalyst materials.Many preparation methods have been developed today,including hydrothermal,sol-gel,microwave,and electrospinning methods.However,it is regrettable that the preparation process of these methods is extremely tedious,the reaction conditions are relatively harsh,and they rely on complex experimental equipment.Therefore,in this paper,Cu-Al-Ti alloy was used as the precursor,nano-porous copper(NPC),nano-porous Cu/Cu₂O composite and nano-CuS were prepared by the dealloying method.The degradation of methylene blue(MB)and methyl orange(MO)dyes was used to investigate the catalytic properties of the materials.Herein,the following work has been carried out:(1)Nanoporous copper(NPC)with a controllable ligament width was prepared by chemically dealloying Cu-Al-Ti amorphous ribbons in dilute HCl solution.The effects of precursor composition,hydrochloric acid concentration,dealloying temperature and dealloying time on the size of nanoporous copper ligaments were discussed.X-ray diffraction and scanning electron microscopy analysis confirmed the 3D,bicontinuous,nanoporous structure constituting fcc-Cu ligaments of 39-79 nm thickness.The coarsening of NPC ligaments increased significantly with an increase of HCl concentration,reaction temperature or time.The increase in size of the Cu ligaments can be described as solid-liquid interface diffusion mechanism.The coarsening index,n,of the Cu ligament was estimated to be 9.1,and the activation energy for ligament coarsening was calculated to be 112.7 k J·mol^-1.Finally,the catalytic activity of NPC was validated with the ultrasound and H₂O₂-assisted degradation of methyl orange(MO),where 99%MO was degraded within 15 min.(2)Nanoporous Cu/Cu₂O composites were successfully prepared by oxidizing nanoporous Cu.Nanoporous Cu/Cu₂O composites inherited the microstructure of nanoporous Cu well.The prepared nanoporous copper was much more active when the concentration of HCl was 0.4 M and the dealloying time was 180 min,which was more prone to oxidation to form Cu₂O.The specific surface area of the nanoporous Cu/Cu₂O composite was 11.7 m²·g^-1.And the best photocatalytic properties which removed MB 65% after 120 min.The degradation rate constant was 0.008 min^-1,which was 1.6 times that of commercial pure Cu₂O powder.(3)A novel CuS photocatlyst was synthesized by chemical dealloying Cu-Al-Ti alloy.The morphologies of the CuS catalyst can be controlled by the composition of the precursor alloys.The dealloyed product with Cu content in the range of 45-55 at.%shows a spherical structure composed of nanosheets.Nanoporous CuS prepared by Cu₅₅Al₃₅Ti₁₀alloy shows the largest specific surface area.In the experiment of photocatalytic degradation toward high concentration MB solution(100 mg L^-1),94%of MB can be removed within 20 minutes.