Synergistic Electronic Modulation in Nitrogen, Sulfur, and Boron-Doped Graphene Nanoribbons for Enhanced Oxygen Reduction Electrocatalysis

The sluggish kinetics of the oxygen reduction reaction (ORR) remains one of the main challenges in the development of efficient and sustainable metal-free catalysts for energy conversion and storage devices. Multielement doping of carbon materials has emerged as an effective strategy to tailor their electronic properties and enhance ORR activity. In this study, graphene nanoribbons codoped with nitrogen, sulfur, and boron (NSB-GNR) were prepared via a facile hydrothermal route, comprehensively characterized and evaluated for ORR catalysis. Characterization by EELS, FTIR, XPS, and ICP-OES confirmed successful heteroatom incorporation and revealed that boron was mainly located in the inner layers of NSB-GNR. Raman analysis suggested that boron incorporation may have induced defect reconstruction within the carbon lattice. Nitrogen adsorption-desorption and zeta potential analyses indicated that the acidic environment generated by boric acid during hydrothermal synthesis partially neutralized surface charges, leading to reduced BET surface area (176 m² g^-1) and pore volume (0.23 cm³ g^-1) compared with the N,S-doped counterpart. Despite this reduction, NSB-GNR exhibited superior ORR performance with an onset potential of 0.805 V, half-wave potential of 0.658 V vs RHE, and a limiting current density of -3.24 mA cm^-2, following an efficient four-electron transfer pathway. These findings demonstrate that the synergistic interactions among nitrogen, sulfur, and boron dominate over textural effects, providing new insights into the cooperative electronic modulation of heteroatoms and offering a scalable strategy for designing advanced metal-free carbon electrocatalysts.