Impact of Electrocatalyst Activity and Ion Permeability on Water-Splitting Photoanodes

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• 作者：Fuding Lin ; Benjamin F. Bachman ; Shannon W. Boettcher
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2015
• 出版时间：July 2, 2015
• 年：2015
• 卷：6
• 期：13
• 页码：2427-2433
• 全文大小：427K
• ISSN：1948-7185

文摘

Electrocatalyst (EC)-modified semiconductor (SC) photoelectrodes are key elements of solar water-splitting systems. The SC|EC interface affects the composite photoelectrode behavior but is poorly understood. We uncover the role of EC activity and SC|EC interface properties using a range of metal (Ni, Fe, Ni鈥揊e, Co, Ir) oxide or (oxy)hydroxide ECs deposited on model single-crystal n-TiO₂ photoanodes. The impedance and photoelectrochemical response of the system was nearly independent of EC oxygen evolution activity if the catalyst was deposited electrochemically as an ion-permeable (oxy)hydroxide or hydrous oxide. When dense oxides (e.g., ion-impermeable) ECs were used, the response depended strongly on the EC. These data demonstrate that the EC and SC interface structures are more important than the EC activity in determining the composite photoanode response, confirming recent SC|EC interface simulations for ion-permeable ECs. These results thus inform the design of high-performance water-oxidizing photoanodes with direct SC|EC interfaces.