Nickel hydroxide electrode with porous nanotube arrays prepared by hydrolysis and cathodic deposition for high-performance supercapacitors

This paper describes a strategy for fabricating porous nanotube arrays and how the Ni(OH)2 electrode composed of porous nanotubes exhibits better pseudocapacitive behavior compared to Ni(OH)2-coated ZnO nanorod and Ni(OH)2 film electrodes. Ni(OH)2 electrode with porous nanotubes is fabricated by hydrolysis and cathodic deposition using electrodeposited ZnO nanorods as a template. The Ni(OH)2 nanoflakes grow on the stainless steel substrate and around the ZnO nanorods during cathodic deposition. After the removal of the ZnO template, hollow nanotubes with porous walls of interconnected nanoflakes are formed. The porous nanotube structure facilitates easy electrolyte transport to the reaction sites and leads to a further increase in the specific capacitance of electrode. The specific capacitance of porous Ni(OH)2 nanotube electrode reaches as high as 1581 F g−1, which is much higher than that of Ni(OH)2-coated ZnO nanorod (874 F g−1) and compact Ni(OH)2 film (569 F g−1) electrodes at a discharge current density of 1 A g−1.