Femtosecond laser patterning with in situ sintering of porous transport layers simultaneously enhance both electron and gas-liquid transport in proton exchange membrane water electrolysis

Ohmic and mass transport losses account for most of the energy consumed by proton exchange membrane water electrolyzers (PEMWEs) operating at high current densities. The critical bottleneck lies in the inherent limitation of current proton transport layers (PTLs), which fail to simultaneously provide both superior electron transport and optimized gas-liquid transport. In this study, we introduced a novel femtosecond laser engineering strategy that simultaneously fabricated patterned through-holes in PTLs and induced the in situ sintering of titanium fibers around the through-holes. This sintering process significantly enhanced the electrical conductivity of the PTL by improving the inter-fiber connections, whereas the engineered through-hole array improved the interfacial contact by increasing the PTL compressibility and reducing the bending strength. Furthermore, these through-holes effectively shortened the bubble removal pathways and lowered the gas breakthrough pressures, thereby alleviating mass transport limitations at high current densities. Electrochemical experiments revealed that the electrolyzer performance increased with increasing the through-hole density. Compared to the commercial PTL, the optimized sample exhibited a 49 mV and 101 mV reduction in ohmic and mass transport overpotentials at 5 A cm-2, respectively, boosting the performance (6.70 A cm-2@2.3 V) by 25.7%. This work offers a promising strategy to further reduce ohmic and mass transport losses in PEMWEs.