Lithium-oxygen (Li-O₂) batteries hold immense promise as next-generation energy storage systems due to their exceptionally high theoretical energy density of 3,500 Wh kg⁻¹. However, their practical application is severely limited by slow reaction kinetics, poor cyclability, and significant charge overpotentials arising from the insulating nature of lithium peroxide (Li₂O₂) and complex side reactions. This study reports a highly efficient bifunctional catalyst composed of monodispersed ruthenium (Ru) nanoparticles anchored on nitrogen-doped reduced graphene oxide (N-rGO), synthesized via an in situ pyrolysis process using melamine and RuCl₃·xH₂O as precursors. The resulting Ru/N-rGO catalyst exhibits exceptional electrochemical performance, delivering a discharge capacity of 17,074 mAh g⁻¹ at 500 mA g⁻¹, a remarkably low charge overpotential of only 0.51 V, and stable cycling for over 100 cycles at 100 mA g⁻¹. These results are attributed to the synergistic effects of uniform Ru nanoparticle dispersion, strong metal-support interaction, and tailored surface chemistry. The Ru nanoparticles serve as active nucleation sites for the formation of a continuous Li₂O₂ film during discharge, which enhances electrical contact and facilitates faster decomposition during charging. X-ray photoelectron spectroscopy (XPS) confirms the presence of Ru⁰ and Ru⁺ species, with a distinct shift in binding energy indicating strong electronic coupling between Ru and nitrogen dopants. This interaction stabilizes the catalyst surface and suppresses parasitic reactions such as Li₂CO₃ formation. High-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) reveal well-defined crystalline Ru nanoparticles (~2.66 nm average size) uniformly distributed across the N-rGO matrix. Energy-dispersive X-ray spectroscopy (EDS) mapping confirms homogeneous distribution of Ru, N, and C elements. Raman and XRD analyses confirm the graphitic structure and metallic phase of Ru, respectively. BET analysis shows a high specific surface area of 884 m² g⁻¹, beneficial for mass transport and catalytic activity.
Electrochemical testing demonstrates that Ru/N-rGO significantly outperforms control samples including pristine N-rGO and Ru/rGO. Cyclic voltammetry (CV) reveals a lower onset potential and higher oxidation current for Li₂O₂ decomposition on Ru/N-rGO, indicating improved oxygen evolution reaction (OER) kinetics. Deep galvanostatic discharge-charge tests show a discharge capacity of 17,074 mAh g⁻¹ with 100% Coulombic efficiency, far exceeding that of N-rGO (8,947 mAh g⁻¹, 85.4% efficiency). Charge overpotentials are drastically reduced: 0.SLC27A5 Antibody Autophagy 51 V for Ru/N-rGO versus 0.78 V for Ru/rGO and 0.92 V for N-rGO. Long-term cycling stability is confirmed over 100 cycles without degradation. UV-vis titration based on [Ti(O₂)]²⁺ complex formation confirms a higher yield of Li₂O₂ and reduced side products on Ru/N-rGO electrodes. Electrochemical impedance spectroscopy (EIS) shows a low charge-transfer resistance of 135.3 Ω and full recovery after cycling, indicating excellent reversibility. Scanning electron microscopy (SEM) images reveal a dense, uniform Li₂O₂ film on Ru/N-rGO after shallow discharge, evolving into compact layers at deeper discharge levels—contrasting with fragmented deposits observed on other catalysts.RAD52 Antibody In Vivo Superoxide adsorption experiments demonstrate a high efficiency of 84.PMID:34809527 7% for Ru/N-rGO, significantly higher than Ru/rGO (55.5%) and N-rGO (48.8%), confirming enhanced O₂⁻ intermediate adsorption due to the Ru–N synergy. Post-cycling XPS analysis shows minimal accumulation of Li₂CO₃ and a moderate increase in oxidized Ru species (from 40% to 46%), suggesting sustained catalytic activity despite some surface oxidation.
This work establishes a clear mechanism for the superior performance of Ru/N-rGO: initial surface-controlled film growth of Li₂O₂, followed by solution-mediated particle deposition at deeper discharge states. The strong Ru–N interaction promotes favorable adsorption of superoxide intermediates, guiding the nucleation pathway toward a conductive film morphology rather than isolated particles. This structural advantage enables rapid electron transfer and lowers the energy barrier for Li₂O₂ decomposition. The design principles demonstrated here—precise control of metal dispersion, strategic doping, and strong metal-support interaction—provide a robust framework for developing advanced bifunctional catalysts for Li-O₂ batteries. By addressing key challenges in reaction kinetics, product morphology, and stability, this catalyst architecture offers a viable path toward practical implementation of high-energy-density lithium-oxygen batteries. The findings highlight the importance of atomic-level engineering in catalyst design and open new avenues for rational development of heterogeneous electrocatalysts in energy conversion and storage technologies.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com
