A faradaic impedance study on the kinetic properties of water photosplitting at illuminated TiO2/solution interface

作者：Zhang, Jing-Wei; Kong, De-Sheng^*; Zhang, Huan; Du, Dan-Dan; Wang, Na; Feng, Yuan-Yuan; Li, Wen-Juan

来源：Journal of Solid State Electrochemistry, 2015, 19(11): 3411-3423.

DOI：10.1007/s10008-015-2948-y

• Photoelectrochemical
• Faradaic impedance
• Equivalent electrical circuit
• Rate constant
• Reaction mechanism
• "EEC-to-kinetics" conversion

Photoelectrochemical (PEC) water oxidation is the key reaction for hydrogen generation from water photosplitting at illuminated n-semiconductor/solution interfaces. In this work, the kinetic property of water photooxidation at TiO2/solution interface, under illumination of simulated sunlight with constant incident light intensity (AM 1.5, 100 mW cm(-2)) and in pH 6-10 solutions (either or not containing carbonate additives), was investigated by using photocurrent measurement and electrochemical impedance spectroscopy (EIS) techniques. Tafel-type behavior was revealed for the potential dependence of photocurrents within a potential region above the photocurrent onset potential. The measured EIS spectra were first analyzed by equivalent electrical circuit (EEC) fitting. Then, by interpreting the Faradaic impedance for the photocharge transfer processes based on a proposed two-step reaction mechanism accounting for the water photooxidation at TiO2 surface, it was shown that more interested and more important kinetic parameters (rate constants and surface coverage of intermediates) can be obtained from the EEC element parameters. Based on the results of this work, novel features for the effects of solution pH and the carbonate addition on the kinetics of water photooxidation were revealed and discussed.

• 出版日期2015-11
• 单位曲阜师范大学