50 research outputs found
Water oxidation at hematite photoelectrodes: the role of surface states
Hematite (α-Fe2O3) constitutes one of the most promising semiconductor materials for the conversion of sunlight into chemical fuels by water splitting. Its inherent drawbacks related to the long penetration depth of light and poor charge carrier conductivity are being progressively overcome by employing nanostructuring strategies and improved catalysts. However, the physical–chemical mechanisms responsible for the photoelectrochemical performance of this material (J(V) response) are still poorly understood. In the present study we prepared thin film hematite electrodes by atomic layer deposition to study the photoelectrochemical properties of this material under water-splitting conditions. We employed impedance spectroscopy to determine the main steps involved in photocurrent production at different conditions of voltage, light intensity, and electrolyte pH. A general physical model is proposed, which includes the existence of a surface state at the semiconductor/liquid interface where holes accumulate. The strong correlation between the charging of this state with the charge transfer resistance and the photocurrent onset provides new evidence of the accumulation of holes in surface states at the semiconductor/electrolyte interface, which are responsible for water oxidation. The charging of this surface state under illumination is also related to the shift of the measured flat-band potential. These findings demonstrate the utility of impedance spectroscopy in investigations of hematite electrodes to provide key parameters of photoelectrodes with a relatively simple measurement
Nanocrystalline Mesoporous Strontium Titanate as Photoelectrode Material for Photosensitized Solar Devices: Increasing Photovoltage through Flatband Potential Engineering
Contribution of organic bulking materials on chemical quality of sewage sludge vermicompost
Energetics of Electron Transfer at the Nanocrystalline Titanium Dioxide Semiconductor/Aqueous Solution Interface: pH Invariance of the Metal-Based Formal Potential of a Representative Surface-Attached Dye Couple
Ionic strength dependence of formation constants. Alkali metal complexes of ethylenediaminetetraacetate nitrilotriacetate, diphosphate, and tripolyphosphate in aqueous solution
Characterization of metal-complex-containing organic polymeric films by secondary ion mass spectrometry
Use of Neutron Reflectivity to Measure the Dynamics of Solvation and Structural Changes in Polyvinylferrocene Films During Electrochemically Controlled Redox Cycling
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(20) (a) He-Ne laser. The quantum efficiency at the maximum photocurrent in this cell was about 95%