Needle-like Cu(OH)2 in situ grown on nanoporous copper ribbon via anodizing route for supercapacitors

In this paper, Cu–Zr–Ni–Be amorphous alloy was dealloyed to prepare nanoporous coppers (NPCs), which were used as substrate to in situ synthesize needle-like Cu(OH)2@NPC composites via anodization. It's found that the pore size of NPCs increases with the increase of dealloying time and temperature, and the distribution of pores and ligaments becomes more uniform, which indicates that the structure of NPCs can be adjustable. Cu(OH)2 nanowires were in situ grown on the surface of NPC substrate through anodization. The growth process of Cu(OH)2 nanowires is related to the anodization time. As the anodization time increases, the morphology of Cu(OH)2 gradually evolves from nanoneedle to nanobeam and finally to nanoflower. Eventually, three-dimensional hierarchical layered porous structure is formed. The formation mechanism of flower-like Cu(OH)2 is discussed. The needle-like Cu(OH)2@NPC composite possesses excellent conductivity and high capacity, so it can be used as electrode material for supercapacitors. As the current density is 3 mA/cm2, the specific capacitance of the composite electrode is 784 mF/cm2. The needle-like Cu(OH)2@NPC composite exhibits 96% of the initial capacitance after 5000 cycles at 10 mA/cm2, which shows good cycle stability.