Department of Information Engineering, University of Brescia, via Branze 38, 25123Brescia, Italy.
INSTM-National Consortium for Materials Science and Technology, UdR Brescia, via Branze 38, 25123Brescia, Italy.
ACS Appl Mater Interfaces. 2022 Dec 21;14(50):56363-56373. doi: 10.1021/acsami.2c17147. Epub 2022 Dec 7.
Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) has been recently proposed for Raman sensing of redox-active species in solution. Here, we investigated the rationale of this approach through systematic experiments, in which the Raman spectrum of PEDOT:PSS was analyzed in the presence of either nonoxidizing or oxidizing electrolytes. The results demonstrated that Raman spectra precisely reflect the conformation of PEDOT units and their interactions with PSS. Two different responses were observed. In the case of oxidizing electrolytes, the effect of charge transfer is accurately transduced in Raman spectrum changes. On the other hand, reduction induces a progressive separation between the PEDOT and PSS chains, which decreases their mutual interaction. This stimulus determines characteristic variations in the intensity, shape, and position of the Raman spectra. However, we demonstrated that the same effects can be obtained either by increasing the concentration of nonoxidizing electrolytes or by deprotonating PSS chains. This poses severe limitations to the use of PEDOT:PSS for this type of Raman sensing. This study allows us to revise most of the Raman results reported in the literature with a clear model, setting a new basis for investigating the dynamics of mixed electronic/ionic charge transfer in conductive polymers.
聚(3,4-亚乙基二氧噻吩)：聚(苯乙烯磺酸盐)（PEDOT:PSS）最近被提议用于溶液中氧化还原活性物质的拉曼传感。在这里，我们通过系统的实验研究了这种方法的原理，在这些实验中，分析了存在非氧化性或氧化性电解质时 PEDOT:PSS 的拉曼光谱。结果表明，拉曼光谱精确地反映了 PEDOT 单元的构象及其与 PSS 的相互作用。观察到两种不同的响应。在氧化性电解质的情况下，电荷转移的效果在拉曼光谱变化中得到了准确的转换。另一方面，还原会导致 PEDOT 和 PSS 链之间逐渐分离，从而降低它们之间的相互作用。这种刺激决定了拉曼光谱的强度、形状和位置的特征变化。然而，我们证明，通过增加非氧化性电解质的浓度或使 PSS 链去质子化，也可以获得相同的效果。这对 PEDOT:PSS 用于这种类型的拉曼传感提出了严重的限制。本研究允许我们用一个清晰的模型修正文献中报告的大多数拉曼结果，为研究导电聚合物中混合电子/离子电荷转移的动力学奠定了新的基础。
