Investigation of Surface and Interface Properties of Photoelectrocatalysts for Solar Fuels
Yan-Gu Lin1*, Yu-Chang Lin1, Yu-Hsueh Chang1, Liang-Ching Hsu1, Po-Yang Peng1
1Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu, Taiwan
* presenting author:Yan-Gu Lin,
Global climate warming and environment pollution have spurred scientists to develop new high-efficient and environmental-friendly energy technologies. Hydrogen is an ideal fuel for fuel cell applications. Hydrogen has to be produced from renewable and carbon-free resources using nature energies such as sunlight if one thinks of clean energy and environmental issues. In this regard, a photoelectrochemical (PEC) cell consisting of semiconductor photoelectrodes that can harvest light and use this energy directly for splitting water is a more promising way for hydrogen generation. Abundant and inexpensive oxide semiconductor such as TiO2 has been recognized as a promising photoelectrode, but the photoconversion efficiency is substantially limited by its large band gap and rapid charge recombination. Recently, iron oxide (Fe2O3) with band gap 2.2 eV attracts increasing attention for the conversion of solar energy because iron is an abundant and cheap material. In this work, electrodeposition was used to fabricate nanostructured films of Ti-containing hematite for application to the PEC splitting of water. The morphology and microstructure of Ti-doped hematite were examined with a scanning electron microscope, X-ray diffraction, Raman spectra and X-ray photoelectron spectra. Optical absorption spectra indicated an enhanced light absorbance in Ti-doped hematite. This Ti doping increased the carrier concentration about ten-fold, confirmed with a Mott-Schottky analysis. The prepared Ti-doped hematite showed a photocurrent enhanced four-fold relative to pristine hematite. Synchrotron-based soft X-ray absorption spectra clearly revealed that a local Fe2TiO5 structure in hematite formed a heterojunction, which decreased the accumulation of photogenerated holes and improved the performance.

Keywords: photoelectrochemical, synchrotron, Hydrogen, photoelectrode, X-ray absorption spectra