Synergistic Assembly of Peptide-Metal Hydroxide Hybrid Nanostructures for Electrochemical Capacitors

Abstract

Electrochemical deposition of metal hydroxide in presence of peptide amphiphile results self-assembled nanoscale hybrid thin films. We demonstrate here the self-assembly of three small aromatic peptides (NmYW, NmFW and NmFY) with three transition metal hydroxides (Co(OH)2, Ni(OH)2 and Zn(OH)2). Here peptides are used as structure directing agent for the construction of organic/inorganic hybrid nanostructured materials. Electrodeposition of different peptide/metal hydroxides is carried out potentoiodynamically applying constant potential using indium tin oxide (ITO) as working electrode. Scanning electron microscopy (SEM) is used to visualize the surface morphology of peptide/metal hydroxide thin films. The interactions among peptides and peptides-metal hydroxides are exhibited using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) studies. Electrochemical measurements are performed to examine the energy storage behavior of peptide/metal hydroxide nanohybrids. Porous nanostructure of peptide/Co(OH)2 hybrid shows high capacitance of 3070 Fg-1 through electron transfer mechanism in the potential range -0.2 to 0.6 V at discharge current of 5 mA. Soft and porous nanostructure facilitates the electrochemical accessibility of electrolyte OH- ions to Co(OH)2 thin films and fast diffusion rate within the redox phase. This study provides a useful platform for the construction of various electrochemically active peptide/metal hydroxide nanoscale hybrid materials which exhibit capacitive electrochemical performance in energy storage applications.