Water Oxidation at Hematite Photoelectrodes with an Iridium-Based Catalyst

详细信息    查看全文

• 作者：Laura Badia-Bou ; Elena Mas-Marza ; Pau Rodenas ; Eva M. Barea ; Francisco Fabregat-Santiago ; Sixto Gimenez ; Eduardo Peris ; Juan Bisquert
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：February 28, 2013
• 年：2013
• 卷：117
• 期：8
• 页码：3826-3833
• 全文大小：446K
• 年卷期：v.117,no.8(February 28, 2013)
• ISSN：1932-7455

文摘

The iridium complex [Cp*Ir(H₂O)₃](SO₄) was used as an organometallic source for the electrodeposition of iridium oxide onto Fe₂O₃. The new iridium-containing electrode allowed us to study the coupling between the photocatalytic properties of hematite and the electrocatalytic properties of the iridium-based material. A cathodic shift of the photocurrent for water oxidation upon electrodeposition of the iridium complex was observed, which increased with increasing surface concentration of IrO_x on Fe₂O₃. The shift for the highest surface concentration of iridium tested amounts to 300 mV at 200 渭A路cm^鈥? current density. The catalytic mechanism of the IrO_x layer was unveiled by impedance spectroscopy measurements fitted to a physical model and can be explained on the basis of a highly capacitive layer, which enhances charge separation and stores photogenerated holes at Fe₂O₃, subsequently oxidizing water. These findings improve our understanding of the mechanism of water oxidation by heterogeneous Ir-based catalysts coupled to semiconductor electrodes.