Abstract:
One dimensional metal oxides are attractive nanomaterials for photoelectrochemical water
splitting application due to the fast charge diffusion in one directional pathway. In this
work I have studied the morphological effect of precursor growth solution concentration
on one dimensional ZnO. Different morphologies including nanowires, nanorods,
nanotubes and nanoflakes was obtained in just one step hydrothermal process at different
concentrations of 25 mM, 50 mM, 100 mM and 200 mM respectively. Heterojunction of
FeVO4@ZnO were prepared by 3x, 6x and 9x times spin coating of FeVO4. These
Morphological structures were confirmed by XRD, SEM-EDX and Raman Spectroscopy.
Thickness and surface roughness were calculated by AFM and optical profilometry. UVVis
Spectroscopy indicated the red shift in band gap of the ZnO which was further reduced
by heterojunction formation due to the enhanced absorption in visible region. The
photoelectrochemical and electrochemical study was done in three electrode system by
using Na2SO3 (pH=7.5) electrolyte. Electrode prepared at 100 mM concentration have
nanotubes of ZnO showed maximum current density of 1.18 mA/cm2 at 1.23 V vs RHE
with donor density of 4.59x1013 and electron life time of 356.9 μs under illumination. The
formation of heterojunction of FeVO4@ZnO nanotubes further enhanced the current
density up to 2.67 mA/cm2 at 1.23 V vs RHE in 6x coated FeVO4 with increased donor
density of 8.52x1013 cm-3 and reduced lifetime of electron up to 86.4 μs under
illumination. Chronoamperometry up to 600 s of illumination at 1.23 V vs RHE showed
that all the electrodes are stability. Mott-Schottky analysis under dark showed the flat
band potential of 0.47 V for 6x coated FeVO4@ZnO nanotubes.
