In situ synthesis of VO2@C nanocomposites for enhanced visible-light photocatalysis in wastewater remediation and sustainable hydrogen generation

Abstract

In this study, we explored the efficacy of VO₂/carbon nanocomposites as promising photocatalysts for hydrogen generation and dye degradation under natural sunlight. These nanocomposites were synthesized using a facile one-step hydrothermal method at 180 °C using dextrose as the carbon source with optimized reaction time. The synthesized materials were characterized using X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) analysis, to confirm their structural and physiochemical properties. FESEM analysis revealed the monoclinic crystalline structure of VO₂, accompanied by the formation of nanosheets surrounding carbon spheres of ∼50 nm in diameter. Optical analysis indicated that the material shows broad absorption in the visible region with a band gap range from 2.24 to 1.87 eV. XPS and Raman spectroscopy provided further confirmation of the successful formation of the VO₂/C composite. Among the synthesized samples, the VO₂/C composite synthesized within 48 hours of hydrothermal treatment (VC-5) exhibited the highest photocatalytic activity. The VC-5 composite exhibited a hydrogen production rate of 2545.24 μmol h⁻¹ g⁻¹ and demonstrated notable photocatalytic efficiency, achieving 97% degradation of methylene blue within 5 minutes and 80% degradation of Victoria blue within 15 minutes under natural sunlight. The enhanced photocatalytic performance of these hybrid nanomaterials is attributed to their large surface area, high porosity, uniform morphology, and the synergistic interaction between VO₂ and carbon. These factors enhance visible light absorption and charge carrier dynamics, significantly improving the photocatalytic performance of VO₂/C nanocomposites.