Iron oxide (n-Fe 2O 3) nanowire films and carbon modified (CM)-n-Fe 2O 3 thin films for hydrogen production by photosplitting of water

Abstract

Iron oxide n-Fe 2O 3 nanowire photoelectrodes were synthesized by thermal oxidation of Fe metal sheet (Alfa Co. 0.25 mm 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 is proportional to photocurrent density, J p. The optimized electric oven-made n-Fe 2O 3 nanowire photoelectrodes showed photocurrent densities of 1.46 mA cm −2 at measured potential of 0.1 V/SCE at illumination intensity of 100 mW cm −2 from a Solar simulator with a global AM 1.5 filter. For the optimized carbon modified (CM)-n-TiO 2 synthesized by thermal flame oxidation the photocurrent density for water splitting was found to increase by two fold to 3.0 mA cm −2 measured at the same measured potential and the illumination intensity. The carbon modified (CM)-n-Fe 2O 3 electrode showed a shift of the open circuit potential by −100 mV/SCE compared to undoped n-Fe 2O 3 nanowires. A maximum photoconversion efficiency of 2.3% at applied potential of 0.5 V/E aoc was found for CM-n-Fe 2O 3 compared to 1.69% for n-Fe 2O 3 nanowires at higher applied potential of 0.7 V/E aoc. These 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).