The effect of the pretreatment processes on the corrosion and stability of titanium porous transport layer in proton exchange membrane water electrolyzer

This study integrates electrochemical testing and physical characterization to systematically examine the impact of pretreatment processes on the performance of titanium-based porous transport layers (PTLs) in proton exchange membrane water electrolyzers (PEMWEs). It is revealed for the first time that surface defects in PTLs are the primary cause of the high-frequency arc phenomenon, challenging the conventional view that attributes this to high-frequency resistance. The investigation further elucidates the dual function of acid etching, which not only removes the oxide layer and forms a titanium hydride (TiHx) layer but also mitigates surface defects, thereby enhancing PTL performance and reducing the incidence of high-frequency arcs. Moreover, the study highlights the potential risks of ultrasonic cleaning, demonstrating that it can exacerbate surface defects, thus increasing high-frequency arcs and titanium corrosion, ultimately diminishing the long-term stability of the electrolyzer. In exploring the protective mechanisms of coatings, it is discovered that while coatings provide short-term protection, the long-term stability of PTLs is contingent upon the improved surface quality achieved through appropriate pretreatment. These interconnected findings offer significant insights into optimizing PEMWE PTL performance and cost-effectiveness.