Nano-wall like visible-light active carbon modified n-TiO2 thin films for efficient photoelectrochemical oxygen separation from water

Abstract

Efficient photoelectrochemical oxygen separation from water was demonstrated using a nano-wall like carbon modified n-type titanium oxide (CM-n-TiO2) electrode during water splitting reaction. The CM-n-TiO2 electrode was synthesized by flame-oxidation of Ti metal sample. The combustion products of natural gas flame acted as the carbon source. The oxygen separation rate during water splitting was evaluated in terms of anodic photocurrent density, Jp, under solar simulated light illumination of 1 sun. Upon incorporation of carbon within the titanium oxide, the photocurrent density was enhanced to 4.97 mA cm−2 at CM-n-TiO2 electrode compared to 0.66 mA cm−2 at regular of n-TiO2 both at the same measured potential of - 0.6 V/SCE. Such a multiple-fold increase in photocurrent density at CM-n-TiO2 thin film electrode was attributed to its enhanced absorption in the UV region, red-shift to visible region due to carbon incorporation and as well as due to pronounced nano-wall like surface morphology generated under the harsh conditions of flame oxidation. CM-n-TiO2 photoelectrodes were characterized in terms of photocurrent measurements under white light and as well as under monochromatic light illuminations, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), the valence band X-ray photoelectron spectroscopy (XPS) and the AC-impedance measurements.