Multifunctional Palladium Incorporated Nitrogen-Doped Graphene Enables Efficacious Oxygen Reduction and Hydrogen Peroxide Reduction Reaction

This work reports the design of a Pd-N-doped reduced graphene oxide (Pd-NGO) composite as a multifunctional material for both the oxygen reduction reaction (ORR) and nonenzymatic H2O2 sensing. Pd-NGO was synthesized via a simple chemical reduction route by using PdCl2 without capping agents or stabilizers. Structural characterization confirmed the uniform dispersion of Pd nanoparticles (3–8 nm) on NGO sheets and their strong coordination with nitrogen dopants. XPS and Raman analysis, supported by density functional theory (DFT) calculations, revealed that pyridinic N sites at graphene edges serve as robust anchoring points, upshifting the Pd d-band center (+0.27 eV) and thereby enhancing oxygen adsorption and promoting a favorable 4-electron ORR pathway in alkaline media. Meanwhile, pyrrolic N contributed to improved nanoparticle stabilization and long-term durability. Beyond its catalytic activity, Pd-NGO was integrated into a screen-printed electrode to develop a nonenzymatic H2O2 sensor, which demonstrated a low detection limit (260 μM), good sensitivity (0.055 μA μM–1cm–2), and excellent selectivity, repeatability, and stability. The combination of scalable synthesis, superior ORR activity, and robust electrochemical sensing performance underscores Pd-NGO as a versatile platform for sustainable energy conversion and practical analytical applications.