Óscar Santiago

Hydrogen crossover, the undesired diffusion of hydrogen from the cathode to the anode in a water electrolyzer, is a critical issue in these devices since it lowers efficiency and poses safety risks. Thus, monitoring hydrogen crossover in real time is highly important. However, existing hydrogen detection methods often rely on complex and/or expensive instrumentation, and are poorly suited for fast screening. Here, a fast and accessible electrochemical method was developed for comparative screening of hydrogen crossover in lab‐scale electrolysis cells under ambient conditions. The detection setup employs a four‐electrode cell configuration, enabling hydrogen production and detection to occur in separate chambers across a test separator. By combining cyclic voltammetry and chronoamperometry, this method allows for relative evaluation of separator performance without the need for complex or costly instrumentation. A set of commercial separators was tested in alkaline electrolytes and a brewery waste‐like salt solution. Results demonstrated that the method could consistently differentiate separators based on their hydrogen crossover performance. This technique enables rapid identification of separators with favorable gas‐blocking characteristics and can potentially be optimized and applied to monitor other compounds, thus offering a practical screening tool for separator selection in various electrochemical applications.

This work addresses for the first time the effect of anode serpentine channel depth on Methanol Electrolysis Cells (MECs) and Direct Methanol Fuel Cells (DMFCs) for improving performance of both devices. Anode plates with serpentine flow fields of 0.5 mm, 1.0 mm and 1.5 mm depths are designed and tested in single-cells to compare their behaviour. Performance was evaluated through methanol crossover, polarization and power density curves. Results suggest shallower channels enhance mass transfer efficiency reducing MEC energy consumption for hydrogen production at 40 mA∙cm⁻² by 4.2%, but increasing methanol crossover by 30.3%. The findings of this study indicate 1.0 mm is the best depth among those studied for a MEC with 16 cm² of active area, while 0.5 mm is the best for a DMFC with the same area with an increase in peak power density of 14.2%. The difference in results for both devices is attributed to higher CO₂ production in the MEC due to its higher current density operation. This increased CO₂ production alters anode two-phase flow, partially hindering the methanol oxidation reaction with shallower channels. These findings underscore the critical role of channel depth in the efficiency of both MEC and DMFC single-cells.