Photoelectrochemical Splitting of Water to H_2 and O_2 at n-Fe_2O_3 Nanowire Films and Nanocrystalline Carbon-Modified (CM)-n-Fe_2O_3 Thin Films

摘要

Iron oxide n-Fe_2O_3 nanowire thin films were synthesized by thermal oxidation of Fe metal sheet (Alfa Co. 0.25mm thick) in an electric oven then tested for their photoactivity. The photoresponse of the n-Fe_2O_3 nanowires was evaluated by measuring the rate of water splitting reaction to hydrogen and oxygen, which was found to be proportional to photocurrent density, j_p. The optimized electric oven-made n-Fe_2O_3 photoelectrodes showed photocurrent densities of 1.32mA cm~(-2) at measured potential of 0.0 V/SCE with photoconversion efficiency of 1.69% at applied potential of 0.70V vs E_(aoc) (electrode potential at open circuit conditions) under illumination intensity of 100mW cm" from a Solar simulator with a global AM 1.5 filter. The photoactivity was improved upon incorporation of carbon into the lattice of n-Fe_2O_3 by flame oxidation at 850°C. The carbon modified (CM)-n-Fe_2O_3 showed enhanced photocurrent response to 3.14mA cm~(-2) at a measured potential of 0.0 V/SCE with an efficiency of 2.23% at applied potential of 0.52V vs E_(aoc) The nanocrystalline CM-n-Fe_2O_3 and n-Fe_2O_3 nanowires thin films were characterized using photocurrent density measurements under monochromatic light illumination, UV-Vis spectra, X-ray diffraction (XRD) and scanning electron microscopy (SEM).