Low-size Ru particles for the construction of 3D RGO/CNT carriers for boosting the oxygen reduction reaction

Abstract

The rational design of three-dimensional (3D) structured carbon-supported catalysts is crucial for enhancing the oxygen reduction reaction (ORR) performance and reducing noble metal reliance. This study developed a microwave-assisted ethylene glycol synergistic co-reduction strategy to construct 3D Ru@RGO/CNT nanocomposites, where carbon nanotubes (CNTs) are embedded within reduced graphene oxide (RGO) sheets, forming an interconnected conductive network. By systematically adjusting the mass ratio of RGO to CNT, the optimized Ru@RGO/CNT-1/2 catalyst exhibits a distinct three-dimensional porous structure, effectively preventing the re-aggregation of RGO, enabling the active sites to be in full contact with O₂ and the electrolyte, and promoting electron transfer. Structural characterization revealed that the 3D support not only enables uniform dispersion and stable anchoring of low-size Ru particles, but also inhibits Ru oxidation. Electrochemical tests demonstrated that the catalyst delivers exceptional ORR activity, with a half-wave potential of 0.85 V, a Tafel slope of 53.14 mV dec⁻¹, and an electrochemically active surface area of 12.21 mF cm⁻², outperforming commercial Pt/C. It also exhibits remarkable stability and methanol tolerance in alkaline environments, retaining 91.49% of its initial current after a 72 000 second durability test. This work offers a universal strategy for designing 3D carbon-supported electrocatalysts, opening a new avenue for the development of low-cost fuel cell technologies.