Synergistic GO/MgO nanocomposites with enhanced charge separation for photocatalytic dye degradation

Abstract

The development of efficient and chemically stable photocatalysts with improved charge separation is critical for the remediation of dye-contaminated wastewater. In this study, graphene oxide-magnesium oxide (GO/MgO) nanocomposites with ultralow GO loadings (0-0.05 wt.%) were synthesized through a co-precipitation route and evaluated for ultraviolet (UV)-driven methylene blue (MB) degradation. X-ray diffraction (XRD) results were consistent with the retention of the cubic MgO phase (JCPDS 45-0946) with crystallite refinement from 20.26 to 13.26 nm, while the slight peak-position variations were more consistent with interfacial strain than definitive lattice substitution. UV-visible diffuse reflectance spectra revealed a red shift and bandgap reduction from 5.11 to 4.71 eV. Fourier transform infrared (FTIR) and Raman spectra showed GO-related functional signatures and a decrease in the I_D/I_G ratio (0.886 → 0.830), suggesting strengthened interfacial interactions with increasing GO loading. The optimized 0.05 wt.% GO/MgO sample achieved 91.6% MB degradation within 180 min and exhibited a 5.24-fold enhancement in the apparent pseudo-first-order rate constant (k = 0.00290 min⁻¹) relative to pristine MgO (0.01518 min⁻¹). Photocatalytic efficiency was maximized at pH 7-9 with a catalyst dosage of 0.75 g L⁻¹, and post-reaction XRD/FTIR analysis indicated good structural stability. The enhancement is attributed to crystallite refinement and GO-MgO interfacial charge-transfer pathways inferred from consistent structural/optical-kinetic correlations.

Keywords

Graphene oxide / Magnesium oxide / Nanocomposites / Photocatalysis / Charge separation / Dye degradation

Funding

None.

Conflict of interest

The authors declare that they have no competing interests.

References

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