Graphene exhibits exceptional mechanical strength, electrical conductivity, and thermal stability; however, scalable synthesis of defect-free single-layer graphene remains a significant challenge. Electrochemical exfoliation, a top-down approach, is a promising method for large-scale graphene production; however, it often introduces structural defects that deteriorate its intrinsic properties. In this study, graphene oxide (GO) was synthesized via electrochemical exfoliation using three different 0.1 M electrolytes: sodium sulfate (Na2SO4), ammonium nitrate (NH4NO3), and ammonium persulfate ((NH4)2S2O8). The resulting GO samples were thermally reduced to obtain reduced graphene oxide (rGO), followed by detailed structural and morphological characterization using x-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy. Among the electrolytes studied, (NH4)2S2O8 resulted in the lowest defect density, as evidenced by Raman spectroscopy, which showed a significant reduction in the <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$I_{{\text{D}}} /I_{{\text{G}}}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>I</mi> <mtext>D</mtext> </msub> <mo stretchy="false">/</mo> <msub> <mi>I</mi> <mtext>G</mtext> </msub> </mrow> </math></EquationSource> </InlineEquation> ratio (from 0.97 to 0.17). Additionally, the <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$I_{{\text{D}}} /I_{{D^{\prime}}}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>I</mi> <mtext>D</mtext> </msub> <mo stretchy="false">/</mo> <msub> <mi>I</mi> <msup> <mi>D</mi> <mo>′</mo> </msup> </msub> </mrow> </math></EquationSource> </InlineEquation> ratio improved from 11.2 to 2.07, indicating a transition in defect nature from sp3-type to graphitic boundary-type defects. Furthermore, a sharp decrease in the full width at half maximum (FWHM) of the D and G bands in rGO-(NH4)2S2O8 indicated improved structural ordering and graphitization. These results highlight the critical influence of electrolyte chemistry on defect engineering in graphene and identify (NH4)2S2O8 as a highly effective medium for producing rGO with minimal defects.

Electrolyte-Mediated Defect Engineering in Electrochemically Exfoliated Graphene

期刊论文
发表日期：

2026年1月3日

查看全文

Nitin Linge,
Pawan Bohane,
Prabhat Kumar Sharma,
Ajeet K. Srivastav

摘要

Graphene exhibits exceptional mechanical strength, electrical conductivity, and thermal stability; however, scalable synthesis of defect-free single-layer graphene remains a significant challenge. Electrochemical exfoliation, a top-down approach, is a promising method for large-scale graphene production; however, it often introduces structural defects that deteriorate its intrinsic properties. In this study, graphene oxide (GO) was synthesized via electrochemical exfoliation using three different 0.1 M electrolytes: sodium sulfate (Na₂SO₄), ammonium nitrate (NH₄NO₃), and ammonium persulfate ((NH₄)₂S₂O₈). The resulting GO samples were thermally reduced to obtain reduced graphene oxide (rGO), followed by detailed structural and morphological characterization using x-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy. Among the electrolytes studied, (NH₄)₂S₂O₈ resulted in the lowest defect density, as evidenced by Raman spectroscopy, which showed a significant reduction in the $I_{{\text{D}}} /I_{{\text{G}}}$ $I_{D} / I_{G}$ ratio (from 0.97 to 0.17). Additionally, the $I_{{\text{D}}} /I_{{D^{\prime}}}$ $I_{D} / I_{D^{'}}$ ratio improved from 11.2 to 2.07, indicating a transition in defect nature from sp³-type to graphitic boundary-type defects. Furthermore, a sharp decrease in the full width at half maximum (FWHM) of the D and G bands in rGO-(NH₄)₂S₂O₈ indicated improved structural ordering and graphitization. These results highlight the critical influence of electrolyte chemistry on defect engineering in graphene and identify (NH₄)₂S₂O₈ as a highly effective medium for producing rGO with minimal defects.