Fe<inf>2</inf>O<inf>3</inf>-TiO<inf>2</inf> nanocomposites for enhanced charge separation and photocatalytic activity

Abstract

© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Photocatalysis provides a cost effective method for both renewable energy synthesis and environmental purification. Photocatalytic activity is dominated by the material design strategy and synthesis methods. Here, for the first time, we report very mild and effective photo-deposition procedures for the synthesis of novel Fe2O3-TiO2nanocomposites. Their photocatalytic activities have been found to be dramatically enhanced for both contaminant decomposition and photoelectrochemical water splitting. When used to decompose a model contaminant herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D), monitored by both UV/Vis and total organic carbon (TOC) analysis, 10 % Fe-TiO2-H2O displayed a remarkable enhancement of more than 200 % in the kinetics of complete mineralisation in comparison to the commercial material P25 TiO2photocatalyst. Furthermore, the photocurrent is nearly double that of P25. The mechanism for this improvement in activity was determined using density functional theory (DFT) and photoluminescence. These approaches ultimately reveal that the photoelectron transfer is from TiO2to Fe2O3. This favours O2reduction which is the rate-determining step in photocatalytic environmental purification. This in situ charge separation also allows for facile migration of holes from the valence band of TiO2to the surface for the expected oxidation reactions, leading to higher photocurrent and better photocatalytic activity. Rise and shine: A very mild and effective photo-deposition procedure for the synthesis of novel Fe2O3-TiO2nanocomposites with dramatically enhanced activity for both contaminant decomposition and photoelectrochemical water splitting compared to benchmark P25 TiO2is reported. The mechanism was determined using density functional theory and photoluminescence, which reveal that the photoelectron transfer is from TiO2to Fe2O3, favouring O2reduction.