质子交换膜水电解池内电化学反应机理和气泡动力学的实验及理论研究

As one of the most promising low temperature electrolysis devices for energy storage, oxygen production and hydrogen production, proton exchange membrane water electrolysis cells’ performance, efficiency and cost are affected by many factors, and the mechanism of its internal electrochemical reaction has not been fully understood. According to the current three-phase boundary theory, electrochemical reactions can occur on the surface of the entire catalyst layer. However, the commercial catalyst layer with uniform distribution of catalyst components to meet the requirements of the three-phase boundary (including catalysts for reaction, conductors for protons and electrons, pathway for reactant and product) is found to have a low catalytic mass activity. By using an advanced characterization system, designing a new proton exchange membrane water electrolysis cell and introducing a tunable film gas-liquid diffusion layer, the micro-space and micro-time scales phenomena of two-phase flow and bubble nucleation, growth and detachment in proton exchange membrane water electrolysis cells will be observed in-situ. The effect of sheet resistance of catalyst layer on bubble nucleation distribution and the consequence of operation parameters on two-phase flow and bubble dynamics will be further discussed. Based on the experimental results, a dynamic model for bubble behavior and a mathematical model for the distribution of electrochemical reactions will be established to further improve the three-phase theory. This proposal is going to reveals the mechanism of electrochemical reaction, the distribution law of reaction site and influence factors in the proton exchange membrane water electrolysis cell in order to lay a foundation both in theory and technique for improving the performance, reducing the cost and optimizing the design of membrane electrode assembly of the proton exchange membrane water electrolysis cell.

作为最具前景的制氢技术之一，质子交换膜水电解池的商业化进程受多种因素的影响，且其内部的电化学反应机理还没有被完全了解。本项目以质子交换膜水电解池内部微空间和微时间尺度下的两相流动形态和气泡动力学行为为研究对象，对电解池内电化学反应机理及反应点分布的规律进行基础科学研究。具体内容包括通过搭建先进的电化学测试和可视化系统、设计新型的质子交换膜水电解池和引入可调节薄膜气液两相扩散层，实时观察不同工况条件下质子交换膜水电解池微通道内两相流的形态变化以及氧气泡的产生、生长和分离现象，探讨催化剂层的薄膜电阻对气泡形核分布以及工作参数对两相流以及气泡动力学行为的影响。根据实验结果建立气泡动力学模型和电化学反应点分布的数学模型，从而完善三相界面反应理论。此项目旨在揭示质子交换膜水电解池内电化学反应机理、反应点分布规律及其影响因素，为有效提高电解池性能、降低生产成本和优化膜电极设计提供理论和技术基础。

质子交换膜水电解池内部的合理设计和制备对其大规模商业化应用有着重要影响。膜电极内的反应机理和质子交换膜水电解池内的传质直接影响着电解池的性能和效率。在本项目的支持下，通过构建多物理场耦合的数学模型对质子交换膜水电解池内部电化学反应和传质现象进行了数值模拟。研究了流场形态、流道数目对质子交换膜水电解池性能的影响；不同工况如电流密度大小、温度、化学计量数等，和不同结构性质如孔隙率、电极电导率等对质子交换膜水电解池性能的影响。通过设计和制备不同阳极催化剂层，揭示薄层电阻和亲疏水性与质子交换膜水电解池中电化学反应的分布和气泡脱离状态直径的影响机制。构建了一套微通道内两相流中气泡脱离的计算模型，数值模拟研究了单个气泡脱离的规律。项目对质子交换膜水电解池电化学反应与两相流传质之间的影响机制的研究，有利于优化膜电极和流场的设计，提高电解水的性能和效率，加速相关领域的商业化应用。