扫描电化学显微镜
微电极
基质(水族馆)
化学
分析化学(期刊)
循环伏安法
吸附
单层
扫描探针显微镜
电化学
电极
材料科学
纳米技术
物理化学
色谱法
地质学
海洋学
生物化学
作者
Athanasios A. Papaderakis,D. Tsiplakides,Stella Balomenou,S. Sotiropoulos
标识
DOI:10.1016/j.elecom.2017.09.003
摘要
Scanning electrochemical microscopy in the surface interrogation mode (SI-SECM) has been used to probe the strength of metal-adsorbed H bonds at Pt and Ir. The generally accepted view is that this technique can only give meaningful results for similar probe and substrate electrode dimensions. However, it is shown that SI-SECM can also provide valuable information for H adsorption even when the substrate is much larger than the microelectrode probe (of 500 and 25 μm diameter respectively), for properly chosen substrate and mediator combinations that minimize the tip currents under substrate open circuit potential conditions. Linear sweep voltammetry at a microelectrode positioned at a very small probe–substrate distance (2.5 μm) showed remarkable positive feedback in the presence of an oxidizable mediator (TMPD) when a full or partial H monolayer was electrochemically pre-formed on the Pt or Ir substrate. The magnitude and shapes of chronoamperometric responses at the tip were interpreted in terms of variation of H coverage with time and changes in the open circuit potential of the substrate. The higher affinity of Ir than Pt for adsorbed H has been used to validate the approach.
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