Electrochemical gelation of quantum dots using non-noble metal electrodes at high oxidation potentials
Electrochemical gelation of quantum dots using non-noble metal electrodes at high oxidation potentials
复制标题
DOI：
10.1039/d1nr06615c
复制
发表时间：
2021-11-30
期刊：
影响因子：
6.7
通讯作者：
Luo, Long
中科院分区：
文献类型：
--
作者：
Hewa-Rahinduwage, Chathuranga C.;Silva, Karunamuni L.;Luo, Long
相对于传统的化学方法，金属硫族化物纳米颗粒的电化学组装可以使用两个额外的杠杆来调整组装过程：电极材料和电势。在我们之前的工作中，通过分别使用相对高电位的贵金属（Pt）电极和相对低电位的非贵金属电极，独立研究了将金属硫族化物量子点（QD）电化学组装成三维凝胶结构的氧化和金属介导的途径。在目前的工作中，我们揭示了在高氧化电位和非贵金属电极（包括 Ni、Co、Zn 和 Ag）条件下两种电凝胶途径之间的竞争，其中两种途径都是活跃的。我们发现在此条件下形成的电凝胶结构取决于电极材料。对于镍来说，主要相是氧化电凝胶，而不是人们所期望的氧化和金属介导的电凝胶的电势依赖性混合物。机理研究表明，金属介导的电凝胶化受到二硫醇盐的抑制，二硫醇盐是氧化电凝胶化的副产物，它会阻断镍电极表面并终止金属离子的释放。相反，对于 Co、Ag 和 Zn，二硫醇盐对电极表面的堵塞效果不如 Ni，因此金属介导的电凝胶化是主要的凝胶化途径。
Relative to conventional chemical approaches, electrochemical assembly of metal chalcogenide nanoparticles enables the use of two additional levers for tuning the assembly process: electrode material and potential. In our prior work, oxidative and metal-mediated pathways for electrochemical assembly of metal chalcogenide quantum dots (QDs) into three-dimensional gel architectures were investigated independently by employing a noble-metal (Pt) electrode at relatively high potentials and a non-noble metal electrode at relatively low potentials, respectively. In the present work, we reveal competition between the two electrogelation pathways under the condition of high oxidation potentials and non-noble metal electrodes (including Ni, Co, Zn, and Ag), where both pathways are active. We found that the electrogel structure formed under this condition is electrode material-dependent. For Ni, the major phase is oxidative electrogel, not a potential-dependent mixture of oxidative and metal-mediated electrogel that one would expect. A mechanistic study reveals that the metal-mediated electrogelation is suppressed by dithiolates, a side product from the oxidative electrogelation, which block the Ni electrode surface and terminate metal ion release. In contrast, for Co, Ag, and Zn, the electrode surface blockage by dithiolates is less effective than for Ni, such that metal-mediated electrogelation is the primary gelation pathway.