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Pulsed laser deposition (PLD) is an appealing technique to fabricate thin films with specific film orientation, stoichiometry, and morphology through tuning of experimental parameters. Here, we present Fe2TiO5, one of the promising photoanode materials, grown on fluorine-doped tin oxide (FTO) substrates through PLD. The structural and morphological properties of Fe2TiO5films grown at room temperature and under varying oxygen pressure were studied. After deposition, all films were annealed in air at 650 °C for 2 h for phase crystallization. Films grown under vacuum (1.1 × 10–6mbar) were compact and dense and had the anticipated stoichiometry but lacked the long-range order expected for a crystalline phase in X-ray diffraction. In contrast, using an oxygen pressure (pO2) of around 9.7 × 10–2mbar during growth resulted in nanoporous, crystalline, and near-stoichiometric films of the orthorhombic Fe2TiO5pseudobrookite phase. These films demonstrated a photocurrent density of around 0.16 mA/cm2at 1.23 V versus RHE and a negative shift in onset potential by 150 mV under backside illumination as compared to the films grown under vacuum. Notably, these films exhibited a preferred (101) orientation of the pseudobrookite grains. This study proposes a viable strategy to fabricate pure-phase and anisotropic Fe2TiO5photoanodes on FTO through PLD. This will pave a way to the synthesis of other complex metal oxide photoelectrodes with precise control over critical properties such as crystallinity, stoichiometry, and porosity that are imperative for their application in solar energy conversion.

We have constructed a Fe2O3/Fe2TiO5heterojunction based photoanode deposited on Fluorine Doped Tin Oxide (FTO) substrate by initially fabricating hematite (Fe2O3) nanorods and subsequently pseudobrookite (Fe2TiO5) nanoporous thin film on top of them. Comparatively lower annealing temperature of 650°C (usually 750°C or above) was used to avoid degradation of FTO. The crystalline Fe2O3/Fe2TiO5heterojunction shows a considerable enhancement in photocurrent density ca. 1.4mA/cm2and high surface charge separation efficiency of 85% at operating voltage of 1.23V vs RHE as compared to its constituents. The crystalline heterojunction showed overall improvement in performance due to enhanced charge separation owing to the favorable band alignment with Fe2O3nanorods and efficient injection of photogenerated holes through surface states into the electrolyte observed through Electrochemical Impedance Spectroscopy.

Ultrathin TiO2is deposited on conventional hydrothermal grown hematite nanorod arrays by atomic layer deposition (ALD). Significant photoelectrochemical water oxidation performance improvement is observed when the ALD TiO2-treated samples are annealed at 650 °C or higher temperatures. The electrochemical impedance spectroscopy (EIS) study shows a surface trap-mediated charge transfer process exists at the hematite–electrolyte interface. Thus, one possible reason for the improvement could be the increased surface states at the hematite surface, which leads to better charge separation, less electron–hole recombination, and hence, greater improvement of photocurrent. Our Raman study shows the increase in surface defects on the ALD TiO2-coated hematite sample after being annealed at 650 °C or higher temperatures. A photocurrent of 1.9 mA cm–2at 1.23 V (vs RHE) with a maximum of 2.5 mA cm–2at 1.8 V (vs RHE) in 1 M NaOH under AM 1.5 simulated solar illumination is achieved in optimized deposition and annealing conditions.

We report the synthesis of iron based titanate (Fe2TiO5) thin films using a simple low cost hydrothermal technique. We show that this Fe2TiO5works well as a photoanode for the photoelectrochemical splitting of water due to favorable band energetic. Further characterization of thin films including band positions with respect to water redox levels has been investigated. We conclude that Fe2TiO5is a promising material comparable to hematite for constructing PEC cells.

Here, we report a significant improvement of the photoelectrochemical (PEC) properties of hematite (α-Fe2O3) to oxidize water by doping with manganese. Hematite nanorods were grown on a fluorine-treated tin oxide (FTO) substrate by a hydrothermal method in the presence on Mn. Systematic physical analyses were performed to investigate the presence of Mn in the samples. Fe2O3nanorods with 5 mol % Mn treatment showed a photocurrent density of 1.6 mA cm–2(75% higher than that of pristine Fe2O3) at 1.23 V versus RHE and a plateau photocurrent density of 3.2 mA cm–2at 1.8 V versus RHE in a 1 M NaOH electrolyte solution (pH 13.6). We attribute the increase in the photocurrent density, and thus in the oxygen evolving capacity, to the increased donor density resulting from Mn doping of the Fe2O3nanorods, as confirmed by Mott–Schottky measurement, as well as the suppression of electron–hole recombination and enhancement in hole transport, as detected by chronoamperometry measurements.

In this Article, we report a strategy to perform in situ incorporation of oxygen evolution catalyst, Co3O4, during hydrothermal growth of Fe2O3nanorod arrays. It was found that the highest photocurrent increase and onset potential shift was observed with 5% Co2+. The photocurrent density increases from 0.72 for the pristine Fe2O3nanorod to 1.20 mA/cm2at 1.23 V versus RHE (i.e., 67% improvement) with 5% Co2+added. Concomitant with this improvement was a shift in the onset potential by ∼40 mV and improvements in incident-photon-to-current efficiencies and oxygen evolution. Hematite photoanodes with in situ deposition of Co3O4nanoparticles showed better performance than those prepared by ex situ procedures because of high surface roughness, larger Co3O4/hematite interfacial area, and smaller Co3O4particle size.