Schmitt Kevin G, Schmidt Ralf, Gaida Josef, Gewirth Andrew A
Department of Chemistry, University of Illinois at Urbana-Champaign, 600 S Mathews Avenue, Urbana, Illinois 61801, USA.
Phys Chem Chem Phys. 2019 Jul 31;21(30):16838-16847. doi: 10.1039/c9cp00839j.
We evaluate the effect of chain length for a series of alkyl sulfonic acid additives on Cu electrodeposition by using a combination of electrochemical and Raman spectroscopic methods. Rotating disk linear sweep voltammetry revealed the influence of these additives on the bulk concentration of Cu+ and on the exchange current densities of the reduction of Cu2+/Cu+ and Cu+/Cu. We then used in situ shell-isolated, nanoparticle-enhanced Raman spectroscopy to correlate the additives' effects on deposition kinetics with their chemical structures at the electrode surface. The combination of these methods suggests that effective Cu electrodeposition acceleration processes require: (1) direct tethering of mercaptoalkylsulfonate species to the electrode, (2) partial desolvation of Cu2+ by the sulfonate group to minimize its solvent reorganization energy, and (3) stabilization of Cu+ adjacent to the electrode surface by addition of halide. The model provides support for recently proposed theories for the electrodeposition of metals where charge is carried across the electrode interface by the cation, rather than the electron.
我们通过结合电化学和拉曼光谱方法，评估了一系列烷基磺酸添加剂的链长对铜电沉积的影响。旋转圆盘线性扫描伏安法揭示了这些添加剂对Cu⁺本体浓度以及Cu²⁺/Cu⁺和Cu⁺/Cu还原反应交换电流密度的影响。然后，我们使用原位壳层隔离纳米颗粒增强拉曼光谱，将添加剂对沉积动力学的影响与其在电极表面的化学结构相关联。这些方法的结合表明，有效的铜电沉积加速过程需要：（1）巯基烷基磺酸盐物种直接连接到电极上；（2）磺酸根基团对Cu²⁺进行部分去溶剂化，以最小化其溶剂重组能；（3）通过添加卤化物来稳定电极表面附近的Cu⁺。该模型为最近提出的金属电沉积理论提供了支持，该理论认为电荷是通过阳离子而非电子穿过电极界面的。
