Modification of hydrothermally synthesized α-Fe2O3 nanorods with g-C3N4 prepared from various precursors as photoanodes for hydrogen production†
Abstract
This report addresses the synthesis, characterisation, and photoelectrochemical performances of α-Fe2O3 nanorods decorated with g-C3N4. Photoanode composites were fabricated in a two-step procedure in which fluorine-doped tin oxide (FTO) glass was coated with α-Fe2O3 nanorods via a hydrothermal method, followed by incorporation of g-C3N4via a wet-impregnation method. In particular, the study investigates the effects of precursors of g-C3N4 (urea, dicyandiamide, and melamine) on the photoelectrochemical properties of the prepared α-Fe2O3/g-C3N4 films. The films were thoroughly analysed by means of X-ray diffractometry (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) surface area analysis, Fourier transform infrared (FTIR) spectroscopy, and UV-vis spectrometry. The highest photoelectrochemical output of the nanorod composite films was achieved with the use of g-C3N4 synthesized from urea, generating 15.3 μA cm−2 of photocurrent density as a result of better charge transfer driven by the formation of a semiconductor heterojunction. This is a staggering 12-fold improvement compared to the unmodified hematite nanorods which managed to only produce 1.2 μA cm−2 of photocurrent density. The merits of g-C3N4 prepared from urea as the best semiconductor couple for α-Fe2O3 are driven by its unique crystallinity and morphology with significantly larger surface area than g-C3N4 prepared from other precursors. The addition of glycerol as a sacrificial agent further improves the photocurrent to ca. 24 μA cm−2. The findings in this study show the potential of α-Fe2O3/g-C3N4 composites for sustainable photoelectrochemical hydrogen production.