Dual Functional Nanostructured Nickel Electrodes on Anodic Alumina for Energy Storage Applications

This study presents a novel approach for fabricating nickel-based nanorod electrodes with dual electrochemical functionality, bridging supercapacitive and faradaic applications. Using nanoporous anodic alumina (NAA) templates and a pulsed electrodeposition technique, two distinct electrode configurations were engineered from a single presubstrate: nickel nanorods in NAA with partially dissolved pore walls (Ni-NR@NAA) and free-standing nickel nanorods after NAA removal and Ni redeposition (Ni-R-NR@NAA). Structural analysis via field-emission scanning electron microscopy (FESEM) confirmed the uniformity and integrity of the nanorods, while their electrochemical performance was evaluated by cyclic voltammetry (CV). The Ni-NR@NAA electrodes demonstrated the pseudocapacitive performance, achieving a capacitance per unit area of 104 mFcm^-2, which is nearly seven times higher than flat nickel electrodes, attributed to the enhanced active surface area and efficient ion transport. Specific capacitance can reach up to 60 Fg^-1 at low scan rates. In contrast, the Ni-R-NR@NAA electrodes exhibited predominantly capacitive behavior with reduced redox activity due to structural modifications. These results emphasize the critical role of nanostructural design in tuning the electrochemical performance, offering a versatile platform for advanced energy storage devices capable of dual supercapacitive and faradaic functionality.