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<p>In this study, Nb-doped V<sub>2</sub>O<sub>5</sub>/rGO composites were synthesized via the hydrothermal method, with reduced graphene oxide contents ranging from 0 to 15% to evaluate their photocatalytic performance in the degradation of methyl orange (MO), rhodamine B (RhB), and malachite green (MG) under UV light. XRD analysis with Rietveld refinement confirmed the stabilization of the orthorhombic alpha-V2O5 phase, where the presence of Nb<sub>2</sub>O<sub>5</sub> signals and a shift in diffraction peaks evidenced lattice expansion induced by doping. Furthermore, XPS analysis revealed the coexistence of mixed oxidation states (V<sup>4+</sup>/V<sup>5+</sup>) and the formation of oxygen vacancies, which are critical for charge transfer. Morphological characterization by SEM showed a structural evolution from microplates in the rGO-free material to a porous network of interconnected nanosheets at 15% rGO. Although thermal stability improved with rGO content, the 5% rGO composite exhibited the optimal photocatalytic activity, achieving removal efficiencies exceeding 90% for RhB and MG. The degradation of malachite green was found to be strongly pH-dependent, suggesting that electrostatic interactions govern the adsorption mechanism. These results point to a synergistic effect between Nb-doping and the rGO network, promoting an efficient Z-scheme charge transfer mechanism.</p>

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Structure and activity relationship of rGO–V2O5/Nb composites in the photocatalytic removal of dyes

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年1月14日

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  • L. J. Cardenas-Flechas,
  • D. F. Avendaño-Rodríguez,
  • N. Fernández-Barrero,
  • D. M. Cuesta-Parra,
  • Irais Mata Guzmán,
  • María A. Acosta,
  • O. Chamarraví-Guerra

摘要

In this study, Nb-doped V2O5/rGO composites were synthesized via the hydrothermal method, with reduced graphene oxide contents ranging from 0 to 15% to evaluate their photocatalytic performance in the degradation of methyl orange (MO), rhodamine B (RhB), and malachite green (MG) under UV light. XRD analysis with Rietveld refinement confirmed the stabilization of the orthorhombic alpha-V2O5 phase, where the presence of Nb2O5 signals and a shift in diffraction peaks evidenced lattice expansion induced by doping. Furthermore, XPS analysis revealed the coexistence of mixed oxidation states (V4+/V5+) and the formation of oxygen vacancies, which are critical for charge transfer. Morphological characterization by SEM showed a structural evolution from microplates in the rGO-free material to a porous network of interconnected nanosheets at 15% rGO. Although thermal stability improved with rGO content, the 5% rGO composite exhibited the optimal photocatalytic activity, achieving removal efficiencies exceeding 90% for RhB and MG. The degradation of malachite green was found to be strongly pH-dependent, suggesting that electrostatic interactions govern the adsorption mechanism. These results point to a synergistic effect between Nb-doping and the rGO network, promoting an efficient Z-scheme charge transfer mechanism.