Enhanced photocatalytic water splitting of a SILAR deposited α-Fe2O3 film on TiO2 nanoparticles

We have investigated the effect of deposition of a alpha-Fe2O3 thin layer on a substrate of TiO2 nanoparticles for photoelectrochemical (PEC) water splitting. The TiO2 layer was coated on an FTO substrate using the paste of TiO2 nanoparticles. The alpha-Fe2O3 layer was deposited on the TiO2 thin film, using the method of Successive Ionic Layer Adsorption and Reaction (SILAR) with different cycles. Various characterizations including XRD, EDX and FE-SEM confirm the formation of alpha-Fe2O3 and TiO2 nanoparticles on the electrode. The UV-visible absorption spectrum confirms a remarkable enhancement of the absorption of the alpha-Fe2O3/TiO2/FTO composite relative to the bare TiO2/FTO. In addition, the photocurrents of the composite samples are remarkably higher than the bare TiO2/FTO. This is mainly due to the low band gap of alpha-Fe2O3, which extends the absorption spectrum of the alpha-Fe2O3/TiO2 composite toward the visible region. In addition, the impedance spectroscopy analysis shows that the recombination rate of the charge carriers in the alpha-Fe2O3/TiO2 is lower than that for the bare TiO2. The best PEC performance of the alpha-Fe2O3/TiO2 sample was achieved by the sample of 70 cycles of alpha-Fe2O3 deposition with about 7.5 times higher photocurrent relative to the bare TiO2.