拓宽银电极上SERS活性的研究电位范围

Extending SERS Activity at Silver Electrodes to a Wide Potential Region

电极表面的粗糙化处理是进行表面增强拉曼光谱（SERS）研究的重要前提,通过研究两种截然不同的氧化还原循环（ORC）粗糙电极的方法，分析其SERS活性稳定电位区间与ORC还原电位之间的关系，发现高活性的SERS位皆处于亚稳状态，易随电极电位越近零电荷电位（PZC）而发生表面原子重排，以至失去活性．引入强吸附物种，可以使特殊ORC得到的SERS活性在PZC以正电位区稳定存在，并可在PZC以负电位得到常规ORC处理的电极表面上的水的SERS信号，大大拓宽了可进行SERS研究的电位范围．

ElectrocheAncal okidation reduction cycle (ORC) is the most common way to create SERS activity at silver electrode surfaces. In the present study, two different types of ORC procedures, a special ORC and a normal ORC, have been used. The reduction potential of the special oRC was about -1.3V, negative to the potential of zero charge (PZC), while for the normal ORC, that was around -0.3 V, positive to the PZC. The SERS activity created by the special ORC was stable at the potentials negative to the PZC and that created by the normal ORC was stable at the potentials positive to the PZC. Using STM and SERS, it was found that the highly active SERS sites were metastable and liable to decompose as the applied potential approach to the PZC due to the rearrangement of the surface atoms (clusters). To avoid the decomposition, a high concentration of Cl-was used so that the SERS active sites could be stabilized as the potential passed across the PZC and the SERS spectra of water at the potential negative or positive to the PZC were able to be obtained under this condition. Therefore, SERS activity can be exten-ded to much wider potential region. A comparison of the SERS behavior created by the two types of ORC is discussed in detail.