Effect of porous transport layer wettability on oxygen transportation in proton exchange membrane water electrolysis

Proton exchange membrane water electrolysis stands as a promising avenue for energy storage in converting renewable energy resources into hydrogen. However, the oxygen management issues at high current densities pose substantial challenges to the system's efficiency and stability. Considering that the porous transport layer (PTL) plays a crucial role in governing the countercurrent transfer of oxygen and the water supply, the impact of PTL wettability on oxygen transport is investigated through the pore-scale simulation. The lattice Boltzmann method model coupled with a reaction boundary instead of using injection boundary simplification is proposed to better describe the mass conversion and oxygen transport dynamics driven by the reaction-introduced pressure variation. The results suggest that hydrophilicity configuration affects the oxygen-water distribution and the oxygen retreat behavior after the breakthrough. Oxygen tends to accumulate in lower hydrophilicity regions. Thus, a synergism of high and low hydrophilicity on the bottom of PTL proves advantageous in reducing oxygen saturation on the CL surface. Constructing the oxygen-water separate transport pathways effectively regulates the oxygen-water distribution and reduces oxygen transport resistance, thus remarkably reducing the oxygen saturation in PTL. These findings contribute to a better understanding of oxygen transport within PTL, facilitating the further development of PTL.