GOALI: A Comparative Study of Electrochemical Codeposition with In-Situ Electron Microscopy

这项提议打算使用各种工具，在IBM的支持和合作下，实时研究电化学共沉积的纳米尺度机制。对于锌-铋和铋-碲共沉积系统，将应用恒电位、恒电流和脉冲控制，同时以良好的时间分辨率(每秒30张图像)和空间分辨率(优于20 nm)对沉积结构的发展形态进行成像-在液体电解液中原位成像。这将为电化学处理过程中纳米级沉积形貌的演变提供独特的计量信息。这项研究解决了目前对共沉积过程的理解中的一个重大差距：不同的过程控制制度和电解液组成下，形貌和化学计量比是如何变化的。本提案中概述的两个模型共沉积系统有望在能源相关技术中使用。在电化学存储结构中，锌阳极长期以来一直很有吸引力，原因是1)与空气或低成本阴极配对时的高能量密度，2)充足，3)成本。到目前为止，由于有树枝状结构的倾向，二次锌阳极一直很难获得。众所周知，铋可以抑制工作锌电池中的放氢，并被添加以延长保质期，因此是一种对镀锌结构感兴趣的添加剂。对于另一种应用，轻微的非化学计量比的碲化铋是热电设备的主要结构，包括冷却设备和发电机。热电效应由互补的p型和n型结构的相对化学性质决定。在实验室之外，这项拟议的研究将为高中生和本科生提供原位显微镜和种子讲座、演示和在线媒体的核心主题。

This proposal intends to use a variety of tools, with support and collaboration from IBM, to study the nanoscale mechanics of electrochemical codeposition in real time. For the zinc-bismuth and bismuth-tellurium codeposition systems potentiostatic, galvanostatic, and pulsed control will be applied while simultaneously imaging the developing morphology of the deposited structure - in situ, within the liquid electrolyte - with good temporal resolution (30 images per second) and spatial resolution (better than 20nm). This will provide unique metrological information on the evolution of the deposit morphology at the nanoscale during electrochemical processing. This study addresses a significant gap in current understanding of codeposition processes: how morphology and stoichiometry vary under different process control regimes and electrolyte compositions.The two model codeposition systems outlined in this proposal have promise for use in energy related technologies. In electrochemical storage structures zinc anodes have long been attractive for reasons of 1) high energy density when paired with air or low-cost cathodes, 2) abundance, and 3) cost. To date secondary zinc anodes have been difficult to achieve due to a tendency toward dendritic structures. Bismuth is known to suppress hydrogen evolution in a working zinc battery and is added to increase shelf life, thus is an additive of interest to plated zinc structure. For another application, slight non-stoichiometries of bismuth telluride are the workhorse structures for thermoelectric devices, both cooling devices and electrical generators. The efficacy of the thermoelectric is determined by the relative chemistries of the complementary p and n type structures. Outside the laboratory the proposed research will serve a core topic of in-situ microscopy and seed lectures, demonstrations and online media for high school and undergraduate students.