Synthesis of mesoporous Co(OH)2 nanostructure film via electrochemical deposition using lyotropic liquid crystal template as improved electrode materials for supercapacitors application

Abstract

Here we report synthesis of mesoporous structure containing two different phases of Co(OH)2 by different routes. The β-Co(OH)2 film and mesoporous α-Co(OH)2 powder synthesized using electrochemical deposition and chemical reduction methods, respectively using lyotropic liquid crystal (LLC) templates. These synthesized mesoporous β-Co(OH)2 film and α-Co(OH)2 powder were utilized as electrode materials for supercapacitors (SCs)application. The surface structure/morphology of these synthesized materials were analyzed by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), wide/low-angle X-ray diffraction (XRD) and Raman spectroscopy. The as-synthesized mesoporous β-Co(OH)2 film and mesoporous α-Co(OH)2 powder contain particles size in the range of 270–300 nm and 70–90 nm, respectively. For application as electrode in SCs, mesoporous β-Co(OH)2 film on FTO reveals enhanced electrochemical performance as compared to mesoporous α-Co(OH)2 powder in 1 M KOH electrolyte as high specific capacitance with a significant tremendous long-term cyclic stability. The specific capacitance of mesoporous β-Co(OH)2 film was 605 F/g at scan rate 10 mV/s and superior cyclic stability as capacitance retention of 94.4% over 2000 cycles. Uniform and homogeneous Co(OH)2 nanoparticles inside film enhance the electrochemical performance for SCs due to easy penetration and access of KOH electrolyte inside mesoporous structure. The reported synthesis method provides a suitable and fast approach to synthesize other kind of metal hydroxide mesoporous structure for electrode purpose for different energy storage devices.