Nanotechnology offers innovative and sustainable solutions for environmental remediation. However, enhancing photocatalytic efficiency remains a significant challenge. In this study, we developed a cost-effective method for synthesising carbon quantum dot (CQD)-incorporated cerium oxide (CeO2) nanocomposites for efficient methyl orange (MO) degradation under direct sunlight. CeO2 nanosols and CQDs were synthesised via sol–gel and hydrothermal processes, respectively, and combined using a hydrothermal route with sonication-assisted mixing. The nanocomposites were calcinated at 600 °C and characterised using XRD, FTIR, Raman, PL spectroscopy, SEM and EDX to analyse their structural, morphological and surface properties. The specific surface area of the CQDs<InlineEquation ID="IEq100"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12043_2025_2997_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="14" /> </InlineMediaObject> <EquationSource Format="TEX">$/$</EquationSource> <EquationSource Format="MATHML"><math> <mo stretchy="false">/</mo> </math></EquationSource> </InlineEquation>CeO2 composites was determined to be 72.3 m2<InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12043_2025_2997_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="14" /> </InlineMediaObject> <EquationSource Format="TEX">$/$</EquationSource> <EquationSource Format="MATHML"><math> <mo stretchy="false">/</mo> </math></EquationSource> </InlineEquation>g from the sol–gel method and 96.7 m2<InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12043_2025_2997_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="14" /> </InlineMediaObject> <EquationSource Format="TEX">$/$</EquationSource> <EquationSource Format="MATHML"><math> <mo stretchy="false">/</mo> </math></EquationSource> </InlineEquation>g from the hydrothermal method, as measured by Brunauer–Emmett–Teller (BET) analysis. The optimised CQDs<InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12043_2025_2997_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="14" /> </InlineMediaObject> <EquationSource Format="TEX">$/$</EquationSource> <EquationSource Format="MATHML"><math> <mo stretchy="false">/</mo> </math></EquationSource> </InlineEquation>CeO2 (1:100 ratio) exhibited enhanced MO degradation, with the MO degradation rate constant for the hydrothermal composite. The energy band gap of the sol–gel composite was found to be 2.78 eV, while the hydrothermal composite showed a band gap of 2.73 eV, facilitating improved light absorption. The degradation efficiency was further influenced by MO concentration, pH and catalyst loading. Additionally, CQDs<InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12043_2025_2997_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="14" /> </InlineMediaObject> <EquationSource Format="TEX">$/$</EquationSource> <EquationSource Format="MATHML"><math> <mo stretchy="false">/</mo> </math></EquationSource> </InlineEquation>CeO2 demonstrated excellent catalytic stability over multiple cycles. These findings highlight the potential of CQDs<InlineEquation ID="IEq101"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12043_2025_2997_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="14" /> </InlineMediaObject> <EquationSource Format="TEX">$/$</EquationSource> <EquationSource Format="MATHML"><math> <mo stretchy="false">/</mo> </math></EquationSource> </InlineEquation>CeO2 nanocomposites for cost-effective water purification and disinfection applications. Graphical abstract

Efficient photocatalytic degradation of methyl orange using cost-effective CQDs$/$CeO₂ nanocomposites synthesised via sol–gel and hydrothermal methods

期刊论文
发表日期：

2025年10月14日

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M D Alshahrani

摘要

Nanotechnology offers innovative and sustainable solutions for environmental remediation. However, enhancing photocatalytic efficiency remains a significant challenge. In this study, we developed a cost-effective method for synthesising carbon quantum dot (CQD)-incorporated cerium oxide (CeO₂) nanocomposites for efficient methyl orange (MO) degradation under direct sunlight. CeO₂ nanosols and CQDs were synthesised via sol–gel and hydrothermal processes, respectively, and combined using a hydrothermal route with sonication-assisted mixing. The nanocomposites were calcinated at 600 °C and characterised using XRD, FTIR, Raman, PL spectroscopy, SEM and EDX to analyse their structural, morphological and surface properties. The specific surface area of the CQDs $/$ $/$ CeO₂ composites was determined to be 72.3 m² $/$ $/$ g from the sol–gel method and 96.7 m² $/$ $/$ g from the hydrothermal method, as measured by Brunauer–Emmett–Teller (BET) analysis. The optimised CQDs $/$ $/$ CeO₂ (1:100 ratio) exhibited enhanced MO degradation, with the MO degradation rate constant for the hydrothermal composite. The energy band gap of the sol–gel composite was found to be 2.78 eV, while the hydrothermal composite showed a band gap of 2.73 eV, facilitating improved light absorption. The degradation efficiency was further influenced by MO concentration, pH and catalyst loading. Additionally, CQDs $/$ $/$ CeO₂ demonstrated excellent catalytic stability over multiple cycles. These findings highlight the potential of CQDs $/$ $/$ CeO₂ nanocomposites for cost-effective water purification and disinfection applications.

Graphical abstract

Efficient photocatalytic degradation of methyl orange using cost-effective CQDs\(/\)CeO2 nanocomposites synthesised via sol–gel and hydrothermal methods

摘要

Efficient photocatalytic degradation of methyl orange using cost-effective CQDs\(/\)CeO₂ nanocomposites synthesised via sol–gel and hydrothermal methods