Castañeda Alma D, Alligrant Timothy M, Loussaert James A, Crooks Richard M
Department of Chemistry, Center for Electrochemistry, and the Center for Nano- and Molecular Science and Technology, The University of Texas at Austin , 105 East 24th Street, Stop A5300, Austin, Texas 78712-1224, United States.
Langmuir. 2015 Jan 20;31(2):876-85. doi: 10.1021/la5043124. Epub 2015 Jan 8.
We report electrochemical catalytic amplification of individual collisions between ∼57 nm diameter Pt nanoparticles (Pt NPs) and 12.5 μm diameter Au ultramicroelectrodes modified with passivating, electrostatically assembled polyelectrolyte multilayer (PEM) films prepared by the layer-by-layer deposition method. Two key findings are reported. First, despite the thicknesses of the insulating PEM films, which range up to 5 nm, electrons are able to tunnel from the Pt NPs to the electrode resulting in electrocatalytic N2H4 oxidation at the PEM film-solution interface. These single-particle measurements are in accord with prior reports showing that the electrochemical activity of passive PEM films can be reactivated by adsorption of metallic NPs. Second, it is possible to control the frequency of the collisions by manipulating the net electrostatic charge present on the outer surface of the PEM thin film. These results, which demonstrate that chemistry can be used to control electrocatalytic amplification, set the stage for future sensing applications.
我们报道了通过逐层沉积法制备的、用钝化的静电组装聚电解质多层（PEM）膜修饰的直径约57 nm的铂纳米颗粒（Pt NPs）与直径12.5 μm的金超微电极之间单个碰撞的电化学催化放大。报道了两个关键发现。首先，尽管绝缘PEM膜的厚度可达5 nm，但电子能够从Pt NPs隧穿到电极，从而在PEM膜-溶液界面处实现电催化肼氧化。这些单颗粒测量结果与先前的报道一致，即被动PEM膜的电化学活性可通过金属NP的吸附而重新激活。其次，通过操纵PEM薄膜外表面上存在的净静电荷，可以控制碰撞频率。这些结果表明化学可用于控制电催化放大，为未来的传感应用奠定了基础。
