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 CO2-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–C2–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.