质子交换膜电解槽具有较高的灵活性与快速响应能力，能够与间歇性可再生能源直接耦合，在全球低碳能源布局中具有较大潜力。目前，该电解槽成本较高，大规模商业化存在较高阻力。本研究以扩散层为切入点，以电解槽小型化、高电密为发展目标。在保证产氢速率一致的情况下，提高系统的电解性能，降低电堆尺寸，实现降本增效。围绕PEM电解槽阴阳极反应界面构筑与水气传质过程，以三合一电极制备与二段复合式电解槽为基础，本文建立了PTL-CL界面定位、两相流观测及实验平台。基于原位可视化的实验手段，研究了阴阳极反应界面的构筑特性、扩散层体内气泡脱离特性、阳极两相流形态规律及对电解槽性能的影响。研究指出，阴阳极反应界面的构筑规律与催化剂层的导电性以及动力学过程密不可分，无序扩散层体内以及PTL-CL界面处水/氧气的传输存在明显的面内扩散作用，较高气体含量的两相流电压响应为秒级响应过程。基于电压分解、电化学阻抗谱和表面形貌表征方式，围绕PEM电解槽极化曲线的滞回原理及阴阳极扩散层结构参数、类型对电解性能的影响机制。提出并建立了APTL-CL的等效欧姆电阻模型，并从阳极三相界面构建的角度提出了PTL-CL界面“基底死区”的概念。针对阳极扩散层的界面构筑规律及传质特性，进行了扩散层结构参数的界面构筑优化及应用激光的界面修饰优化。另外，与阳极规律不同的是，CPTL-CL为e——H3O+的两相界面构筑，孔径参数对性能的影响较小，孔隙率参数对性能影响较大。降低阴极扩散层孔隙率有利于两相界面构筑，降低欧姆面电阻值。为深入理解PEM电解槽的内部状态，建立了耦合了反应动力学、MEA状态、两相传输、热量传导多物理场的PEM电解槽模型。首先定位了PEM电解槽阳极两相流的分布状态，阳极侧气体含量较高的两相流会导致MEA的膜水含量的降低，MEA温度升高。温度对电解槽性能的影响略大，单流道尾端电流密度表现为提升。另外，模型分析了阳极扩散层的结构参数对PTL-CL界面传质特性与MEA状态的影响，验证了前文提出的“基底死区”的概念。本研究对扩散层进行了结构参数扫描的电解槽状态分析，结果指出，高孔隙率小孔径的扩散层性能表现较好，小孔隙率大孔径的扩散层不适用于PEM水电解。

The proton exchange membrane electrolyzer has high flexibility and fast response capability, and it can be directly coupled with intermittent renewable energy sources, which has greater potential in the global low-carbon energy layout. Currently, the electrolyzer has high cost and it is difficult to realize large-scale commercialization. In this study, the porous transport layer is taken as an entry point, the miniaturization of the electrolyzer and high electric density are the development goals. Under the circumstance of ensuring the consistent rate of hydrogen production, if the electrolysis performance of the system is improved, accordingly the size of the electrostack is reduced to realize cost reduction and efficiency. Focusing on the cathode and anode porous transport layer reaction interface construction and mass transfer characteristics, this paper establishes a 3-in-1 electrode preparation PTL-CL interface observation platform, a two-stage composite electrolyzer experiment and observation platform. Based on the experimental method of in-situ visualization, the interface construction of cathode and anode bubble generation sites, bubble detachment characteristics within the porous transport layer, the morphology of anode two-phase flow and its influence on the performance of electrolyzer have been studied. The study indicates that the structure of the cathode and anode interfaces is closely related to the electrical conductivity of the catalyst layer and the kinetic process. The water and oxygen transport within the disordered porous transport layer and at the PTL-CL interface is characterized by a significant in-plane diffusion effect. Based on the voltage decomposition method, electrochemical impedance spectroscopy and surface morphology characterization, the hysteresis principle of the polarization curve of the PEM electrolyzer and the influence mechanism of the structural parameters and type of cathode and anode porous transport layer on the performance have been investigated. The equivalent ohmic resistance model of APTL-CL is proposed and established, and the concept of " substrate deadline " at the PTL-CL interface is proposed from the perspective of the construction of the anode three-phase interface. With regard to the interface construction law and mass transport characteristics of the anode porous transport layer, the optimization of the interface construction with structural parameters and the optimization of the interface modification with the application of laser have beencarried out. In addition, unlike the anode law, CPTL-CL interface is e——H3O+ two-phase interfacial construction, and the pore size parameter has less influence on the performance. Reducing the porosity of the cathode porous transport layer is beneficial to the two-phase interfacial construction and reduces the ohmic surface resistance value.In order to deeply understand the internal state of the PEM electrolyzer, the PEM electrolyzer model coupled with multi-physics fields of reaction kinetics, MEA state, two-phase transport, and heat conduction has been established. Firstly, the distribution state of two-phase flow at the anode of the PEM electrolyzer is localized, and the twophase flow with higher gas content at the anode side leads to the decrease of the membrane water content in the MEA and high MEA temperature, the latter has a slightly higher impact on the performance of the electrolyzer, and the single-flux channel tail-end current density exhibits an elevated current density. In addition, the model analyzes the influence of the structural parameters of the anode porous transport layer on the mass transport characteristics of the PTL-CL interface and the state of the MEA, and it verifies the concept of "substrate deadline" proposed in the previous section. The structural parameters of the porous transport layer have been scanned and analyzed, the results indicate that the performance of the porous transport layer with high porosity and small pore size is better, while the performance of the porous transport layer with small porosity and large pore size is poorer and is not suitable for PEM electrolysis.