Review of control methods of hydrogen in water oxygen by alkaline electrolysis

With the continuous growth of the global demand for green hydrogen energy, Alkaline Water Electrolysis (AWE) technology has become the dominant technology path for large-scale production of green hydrogen by virtue of its mature technical system and significant cost advantages. However, the Hydrogen to Oxygen (HTO) penetration problem in alkaline electrolyzer has become a key factor restricting its safety and hydrogen production efficiency improvement under low current density operating conditions. This paper aims to comprehensively review the formation mechanism, key influencing factors and control strategies of HTO in the AWE process, so as to provide theoretical basis and technical support for the optimization and development of hydrogen production technology from alkaline electrolysis water. The formation of HTO is a complex process involving the coupling of multiple physical fields, which mainly includes hydrogen diffusion across the membrane, alkali convection transport, electroosmotic drag effect, hydrogen supersaturation in the electrolyte, and the mixed cycle of the cathode and anode electrolyte. Among them, the electrolyte mixing cycle was identified as the dominant factor in HTO formation. Based on the existing research, this paper deeply analyzes these mechanisms, and quantifies the influence of different transport mechanisms on HTO concentration through simulation and experimental means. This paper systematically summarizes the current main strategies for HTO control. It includes the research and development of new diaphragm materials (such as PPS modified membrane, titanium dioxide composite membrane, etc.), the improvement of catalyst (such as the optimization of bubble behavior by adding surfactant), the optimization of electrolytic cell structure (such as the introduction of functional thin interlayer, the third electrode, etc.), the regulation of external environment (such as the use of ultrasonic, magnetic field to promote bubble escape) and the precise control of system parameters (such as temperature, pressure, lye flow rate adjustment). Most importantly, the lye separation cycle technology has been proved to be the most direct and effective method to control HTO. Although it faces challenges such as lye concentration imbalance, it can be effectively solved by regularly switching cycle modes. This paper also compares and analyzes each control strategy, and points out their advantages, disadvantages and applicable scenarios. Future research should focus on exploring efficient, low-cost and easy to engineer HTO control strategies, such as combining artificial intelligence and machine learning technology to achieve accurate modeling and predictive control of electrolytic systems. At the same time, it is of great significance to strengthen the research and development and testing of new diaphragm materials and efficient catalysts to promote the further development and application of hydrogen production technology from alkaline electrolysis water. In conclusion, this paper provides a systematic theoretical review and practical guidance for the effective control of HTO in the process of hydrogen production from alkaline electrolytic water, which is helpful to improve the safety and hydrogen production efficiency of alkaline electrolytic cells, and promote the sustainable development of hydrogen energy industry.