Rapid Characterization of Oxygen-Evolving Electrocatalyst Spot Arrays by the Substrate Generation/Tip Collection Mode of Scanning Electrochemical Microscopy with Decreased O2 Diffusion Laye

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• 作者：Alessandro Minguzzi ; Dario Battistel ; Joaquin Rodr铆guez-L贸pez ; Alberto Vertova ; Sandra Rondinini ; Allen J. Bard ; Salvatore Daniele
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：February 12, 2015
• 年：2015
• 卷：119
• 期：6
• 页码：2941-2947
• 全文大小：301K
• ISSN：1932-7455

文摘

A simple approach for the screening of oxygen evolution reaction (OER) electrocatalyst arrays by scanning electrochemical microscopy (SECM) in the substrate generation/tip collection (SG/TC) mode is described. The methodology is based on the application of a series (9鈥?0 replicates) of double-potential steps to a catalytically active substrate electrode, which is switched between potentials where it displays OER activity and inactivity. With an SECM tip coaligned to a given electrocatalyst spot, the dual potential step is applied for a relatively short time in order to restrict the growth of the resulting O₂ diffusion layer. The SECM is then able to measure the O₂ produced while the potential sequence prevents the overlap of the diffusion layer from neighboring spots. With this approach, each spot of material in an array of Ir:Sn oxide compositions (disk shaped, about 150 渭m radius) was examined independently at a constant distance. The method was tested for a series of oxygen evolution catalysts made of SnO₂鈥揑rO₂ mixtures, with compositions varying between Ir:Sn 100:0 to Ir:Sn 0:100. Optimal conditions for avoiding overlapping of the diffusion profiles generated at each spot of the substrate were evaluated by digital simulation. The results obtained for the activity of SnO₂鈥揑rO₂ mixtures using this new technique were validated by comparison to reported results using SECM and other techniques.