Examination of the spatially heterogeneous electroactivity of boron-doped diamond microarray electrodes
Examination of the spatially heterogeneous electroactivity of boron-doped diamond microarray electrodes
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DOI：
10.1021/ac0520994
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发表时间：
2006-04-15
影响因子：
7.4
通讯作者：
Macpherson, JV
中科院分区：
文献类型：
--
作者：
Colley, AL;Williams, CG;Macpherson, JV
研究了完全由金刚石制成的微阵列电极的电学和电化学活性的空间变化。该阵列包含类似于直径50 μ m的掺硼金刚石（BDD）圆盘，间隔250 μ m（中心到中心），在绝缘的内禀金刚石支撑中，使得BDD区域与内禀金刚石共面。原子力显微镜（AFM）表面成像显示阵列表面的粗糙度不超过10纳米。阵列内的每个BDD微盘都包含多种不同颗粒的多晶BDD。使用导电afm，发现不同颗粒的电导率在BDD微磁盘内是不同的。利用扫描电化学显微镜在衬底生成-尖端收集模式下对微盘电极的电活性进行了电化学成像，结果表明，在明显限制扩散的稳态条件下，电极之间的响应变化很小。然而，阵列中的大多数电极似乎主要表现为金属行为。对于活性较低的电极，微盘内的所有颗粒都支持电子转移，尽管速度不同，正如对金属银电沉积的研究所证明的那样，其电位远负于氧端聚晶金刚石的平带电位。在电分析应用中，使用这些阵列电极进行稳态扩散限制测量的可能性是深远的。然而，在伏安测量的动力学分析中应该谨慎，因为当电位低于扩散限制值时，单个颗粒的电活性变化很大。
Spatial variations in the electrical and electrochemical activity of microarray electrodes, fabricated entirely from diamond, have been investigated. The arrays contain similar to 50-mu m-diameter boron-doped diamond (BDD) disks spaced 250 mu m apart (center to center) in insulating intrinsic diamond supports, such that the BDD regions are coplanar with the intrinsic diamond. Atomic force microscopy (AFM) imaging of the surface reveals a roughness of no more than 10 nm over the array. Each BDD microdisk within the array contains polycrystalline BDD with a variety of different grains exposed. Using conducting-AFM, the conductivity of the different grains was found to vary within a BDD microdisk. Electrochemical imaging of the electroactivity of the microdisk electrodes using scanning electrochemical microscopy operating in substrate generation-tip collection mode revealed that, under apparently diffusion-limited steady-state conditions, there was a small variation in the response between electrodes. However, the majority of electrodes in the array appeared to show predominantly metallic behavior. For the electrodes that showed a lower activity, all grains within the microdisk supported electron transfer, albeit at different rates, as evidenced by studies on the electrodeposition of metallic silver, at potentials far negative of the flat band potential of oxygen-terminated polycrystalline diamond. The possibility of using these array electrodes for steadystate diffusion-limited measurements in electroanalytical applications is far-reaching. However, caution should be exercised in the kinetic analysis of voltammetric measurements, since wide variations in the electroactivity of individual grains are apparent when the potential is below the diffusion-limited value.