Probing the Gas/Water Interface on Electrochemically-Generated Nanobubbles

在化学系化学测量和成像(CMI)计划的支持下，华盛顿大学的张波教授和他的研究小组正在开发和应用新的方法来研究电化学产生的纳米气泡的气/水界面。发生在电极/溶液界面的过程，包括气泡的形成，在电化学中起着关键作用。许多与能量转换和储存以及环境化学相关的电化学反应都是放气反应。例如，H_2和O_2是由电催化分解水产生的。尽管气泡形成的早期阶段很重要，但由于缺乏具有足够灵敏度和分辨率的适当成像工具，它的研究仍然具有挑战性。在这个项目中，张团队正在开发一种单分子荧光成像方法来探测纳米气泡的表面，以进一步了解纳米级气体/溶液界面的化学性质。这项研究寻求对电催化反应的更好理解，这将使更有效和更有选择性的催化剂的开发成为可能。该项目为研究生、本科生和高中生在电化学、荧光显微镜、纳米技术和能量存储领域提供了独特的跨学科培训机会。该项目中开发的测量方法旨在更好地了解纳米气泡的气体/溶液界面的化学环境。为此，张教授带领的研究小组对单个荧光团的动态吸附和解吸过程进行了分析。他们正在努力提取一系列关键的动力学参数，包括吸附平衡常数、吸附和解吸动力学常数以及分子在界面上的粘连概率。他们使用溶致变色染料分子来探测界面的极性。此外，研究小组将对纳米电极上产生的单个纳米气泡进行成像，以更好地将荧光信号与气泡的大小和形状关联起来。这项研究有望为纳米级气泡的气体/溶液界面的化学和物理性质提供新的见解，这对清洁能源和其他催化过程的发展具有重要意义。纳米电极及其阵列的使用将使人们能够更好地理解气泡成核过程中的传质效应。除了这项工作的科学影响外，该项目还为学生提供高级培训机会。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With support from the Chemical Measurement and Imaging (CMI) Program in the Division of Chemistry, Professor Bo Zhang and his research group at the University of Washington are developing and applying new approaches to study the gas/water interface of electrochemically generated nanobubbles. Processes that occur at the electrode/solution interface, including bubble formation, play a critical role in electrochemistry. Many electrochemical reactions that are relevant for energy conversion and storage and environmental chemistry are gas-evolving reactions. For example, H2 and O2 are produced from the electrocatalytic water splitting. Despite its key importance, the early stage of bubble formation remains challenging to study due to the lack of proper imaging tools with sufficient sensitivity and resolution. In this project, the Zhang group is developing a single-molecule fluorescence imaging approach to probe the surface of nanobubbles in order to further understand the chemical nature of the nanoscale gas/solution interface. The research seeks an improved understanding of electrocatalytic reactions that will enable the development of more efficient and selective catalysts. This project provides unique interdisciplinary training opportunities for graduate, undergraduate, and high-school students in the areas of electrochemistry, fluorescence microscopy, nanotechnology, and energy storage.The measurements being developed in this project seek a better understanding of the chemical environment at the gas/solution interface of nanobubbles. Toward this goal, the research team led by Professor Zhang analyzes the dynamic adsorption and desorption processes of single fluorophores. They are working to extract a series of key kinetic parameters including the adsorption equilibrium constant, adsorption and desorption kinetic constants, and the sticking probability for molecules at the interface. They use solvatochromic dye molecules to probe the polarity of the interface. Moreover, the research team will image single nanobubbles generated on nanoelectrodes to better correlate fluorescence signal with bubble size and shape. The research promises to offer new insights on the chemical and physical nature of the gas/solution interface of nanoscale bubbles that has important implications for developments in clean energy and other catalytic processes. The use of nanoelectrodes and their arrays will enable a better understanding of mass-transfer effects in bubble nucleation. In addition to the scientific impacts of the work, the project provides advanced training opportunities for students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.