Laser-induced graphene electrocatalyst layer for oxygen reduction reaction in proton exchange membrane fuel cells

The development of cost-effective and durable electrocatalysts capable of replacing platinum in proton-exchange membrane fuel cells (PEM-FCs) remains a major barrier to large-scale implementation. Here, we present a one-step laser-assisted strategy to produce a nitrogen and sulfur co-doped laser-induced graphene (N/S-LIG) electrocatalyst layer (EL). The EL is generated by CO 2 -laser processing of a multilayer assembly composed of a NaOH-treated polyacrylonitrile (PAN) nanofiber mat deposited onto a sulfonated poly(ether ether ketone) (SPEEK) membrane. Laser irradiation enables the simultaneous in situ carbonization of both polymers, yielding a graphene-like architecture featuring hierarchical porosity and intrinsic N/S co-doping. Structural and spectroscopic analyses reveal the formation of N–C 2 –S and N–C–S configurations, confirming the cooperative contribution of both heteroatoms to the catalytic function. Electrochemical measurements in acidic media demonstrate an efficient four-electron oxygen reduction reaction (ORR) pathway, with an onset potential of 0.94 V versus RHE, comparable to commercial Pt/C. Under gas-diffusion electrode operation, the N/S-LIG catalyst delivers a fivefold current increase relative to S-doped LIG, highlighting the impact of dual-heteroatom incorporation. This scalable, chemical-free method offers a direct route to high-performance, metal-free ORR catalysts, supporting the advancement of practical LIG-based electrodes for next-generation fuel cells and enabling broader adoption in energy conversion technologies worldwide applications.