Modified Semiconductor Photoelectrodes for Water Oxidation

Several methods for improving the properties of photoelectrodes are described. A) Amorphous materials were prepared and modified for better photo properties. Pb-Bi-Sn oxide system was prepared on FTO glass and characterized. By modification, the amorphous photoelectrode could perform as well as crystalline materials with regards to photo properties. B) Surface modification was investigated and successfully improved the photocurrent of a hematite nanotube film photoelectrode. The modification is unlike most methods used in previous reports, as only trace amounts of metal ions remain on the surface of the hematite. The surface defects were filled and this improved the charge transport. The Zn doped sample showed most enhancement; the photo current at 1.23 V vs RHE under 1 sun light reached 1.03 mA/cm2 which is 77.6 % higher than the unmodified pure Fe2O3 electrode. C) Unique surfaces were prepared for better photo performance. Electrospinning was applied to prepare nanofibers on the surface of FTO glass. This 3D framework structure has a high surface area and acted as support for semiconductor loading. The characterization and PEC experiments show that the photocurrent was directly related to the load of the semiconductor, and the fibers sample afforded more loading. The limit of this method is the heating temperature which should be kept under a threshold value to keep the stability and tenacity of nanofibers. Characterization methods were used to get details of the samples’ structure, morphology, composition, light absorbance and dopant distribution. Different PEC experiments, such as LSV, CPE, IPCE, Mott-Schottky measurement, EIS, et al., were applied to study the photo properties and mechanism of enhancement. New methods have been developed to improve photoelectrodes and there is potential for other materials and applications.