Scanning electrochemical microscopy.: 57. SECM tip voltammetry at different substrate potentials under quasi-steady-state and steady-state conditions
Scanning electrochemical microscopy.: 57. SECM tip voltammetry at different substrate potentials under quasi-steady-state and steady-state conditions
复制标题
DOI：
10.1021/ac070021c
复制
发表时间：
2007-07-01
影响因子：
7.4
通讯作者：
Bard, Allen J.
中科院分区：
文献类型：
--
作者：
Zoski, Cynthia G.;Luman, Charles R.;Bard, Allen J.
我们讨论了SECM尖端伏安法，其中将UME尖端保持在大约尖端半径内的导电基板上方，并记录尖端伏安图，因为其电势会缓慢扫描，同时将基板保持在固定电势。当更改底物的电势时，一系列稳态尖端伏安图提供了有关反应物和产品的信息。当设置底物E-S，E-E-的电势使底物的反应与尖端（通常的SECM条件）相反时，记录了总阳性反馈（TPF）尖端伏安图。当将底物电势设置为底物的反应与尖端上的反应相同的值时，将尖端与大量溶液中的物种相屏蔽。根据底物电位，这可能导致全部反馈/部分屏蔽（PF-PS）结果的总屏蔽（TS）或伏安图。结果是一系列以TPF，PF-PS或TS为特征的尖端伏安图，具体取决于E-S。据报道，据报道，TCNQ可逆降低和MECN中二代二世的氧化产生的实验尖端伏安图。将这些与开发的模拟和近似方程的分析进行比较，以描述TPF，TS或PF-PS条件下产生的尖端伏安图的特征。还解决了扩散系数之比对UME尖端达到真实稳态状态的能力的影响，并可能采用有关电化学反应的可逆性，电化学反应的可逆性，该产品的稳定性，或该物种的扩散系数的信息，讨论了电化学的稳定性。
We discuss SECM tip voltammetry, where a UME tip is held above a conductive substrate within about a tip radius and a tip voltammogram is recorded as its potential is slowly scanned while the substrate is held at a fixed potential. When the potential of the substrate is changed, the series of steady-state tip voltammograms provide information about the reactants and products. When the potential of the substrate, E-S,E- is set so that the reaction at the substrate is opposite to that at the tip (the usual SECM conditions), a total positive feedback (tpf) tip voltammogram is recorded. When the substrate potential is set to values where the reaction at the substrate is the same as that occurring on the tip, the tip is shielded from the species in the bulk solution. Depending upon the substrate potential, this can cause total shielding (ts) or a voltammogram that is the result of partial feedback/partial shielding (pf-ps). The result is a series of tip voltammograms that are characterized by tpf, pf-ps, or ts, depending upon E-S. Experimental tip voltammograms resulting from the reversible reduction of TCNQ and oxidation of ferrocene in MeCN are reported. These are compared with those from simulations and approximate equations developed to describe the features of the tip voltammograms generated under tpf, ts, or pf-ps conditions. The effect of the diffusion coefficient ratio on the ability of the UME tip to reach a true steady state is also addressed and possible applications, e.g., obtaining information about the reversibility of an electrochemical reaction, the product of an electrochemical reaction, the stability of that product, or the diffusion coefficients of the electroactive species, are discussed.