单纳米气泡及相关三相界面的电化学研究

In-situ study of the surface nanobubbles is of great importance for the fundamental surface science as well as its application in mining industry, medicine and energy technology. Based on our previous discovery of electrochemical generation of single gas nanobubbles at the nanoelectrodes, this project aims to develop an in situ quantitative detection and analysis platform for single nanobubbles dynamics and the three-phase boundary at surface using a combination of scanning electrochemical microscopy and the dark field optical microscopy. First, by confining the nanobubble within the gap between two electrodes, the dynamics including nucleation, growth, and dissolution can be captured from the feedback current at the probe. After obtaining a stable single gas bubble at the nanoelectrodes, the electron transfer reaction at the three-phase boundary will be evaluated by conducting electrochemistry and SECM, leading to a mechanistic understanding of surface nanobubble stability. Furthermore, we will establish a high sensitivity, high time resolution dark field microscopic technique coupled with nanoelectrochemistry for single nanobubble dynamics and attempt the quantitative estimation for the nucleation rate and further correlation to nucleation potential, gas supersaturation, electrode materials and size. The completion of current project will only lead to a better understanding for the physics of surface nanobubbles, but may also provide a new and fast method for nanomaterial electrocatalyst screening.

针对固液界面纳米气泡的原位研究无论从界面科学基础理论还是其在工业、医学、能源等应用领域来说都具有非常重要的意义。本项目基于纳米电极电化学产生单个纳米气泡的独特平台，拟利用扫描电化学显微镜(SECM)和暗场显微镜(DMF)技术构建界面单纳米气泡以及三相电化学界面的定量检测方法，研究相关基础科学问题。项目首先结合SECM的探针反馈对界面单个纳米气泡成核、生长、溶解等演变过程开展机理研究；在精准控制获得稳定单个界面纳米气泡后，构建气/液/固三相电化学界面开展物质传递和电子转移的机理研究，探究电极接触线宽尺寸，以期阐明界面纳米气泡的稳定机制；进一步耦合纳米电化学和DFM方法对单个纳米气泡的动态演变进行高灵敏度高时间分辨检测成像，揭示成核速率与成核电压、成核浓度、电极尺寸、材料HER活性的定量依赖关系。本项目的完成不仅可以阐明诸多界面气泡的科学问题，还有望为纳米催化剂材料的快速筛选提供一种可能。

纳米气泡广泛存在于许多自然现象和工业生产过程，其自身具有独特的物理化学性质。由于涉及气体反应的纳米电催化及能源转化技术的迅速发展，有关纳米气泡的电化学研究越来越受研究者的关注。针对电极界面纳米气泡的研究不仅有助于实现对气泡行为的调控,指导产气反应催化剂电极界面的合理设计以提高电催化效率，揭示纳米催化剂本征电催化活性和界面电荷转移过程,还可以加深对气泡相变成核这一基本物理化学现象的深刻理解。本项目紧紧围绕界面纳米气泡复杂体系电分析化学的新原理、新方法和新技术开展研究工作，主要从以下四个方面开展了研究：(1)自主搭建了一种新型液滴扫描电化学池显微成像平台，首次在单个纳米气泡水平对气泡成核浓度进行了直接测量，并建立了纳米液滴微观传质过程有限元计算理论模型；(2)设计构筑了结构可控电极界面，基于新型液滴扫描电化学池显微镜方法探究了电极界面纳米气泡异相成核机制；(3)实现了单个纳米气泡形成、生长、脱离等动态演变行为的监测与分析，建立了气/液/固三相界面理论模型，提出了界面纳米气泡稳定新机制；(4)拓展了新型液滴扫描电化学池显微镜技术方法在能源分析化学和材料分析化学中的应用。项目执行期间，共发表SCI论文13篇，其中影响因子大于5的文章5篇，包括Journal of the American Chemical Society 1篇, Analytical Chemistry 2 篇, ACS Sensors 1篇, Green Chemistry 1篇，ESI高被引论文1篇。项目研究人员受邀在Journal of the Physical Chemistry Letters 撰写关于nanoscopic investigation of electrolytic gas evolution评述(Perspective, 见附件邀请函)1篇，在中国科学：化学 (2021, 51, 310-322)撰写纳米气泡电化学研究进展综述1篇。参加国际会议8人次，国内会议10人次，5人获得硕士学位。