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<p>A series of Bi<sub>2</sub>S<sub>3</sub>–Graphene–Ti<sub>3</sub>C<sub>2</sub> (BTG) nanocomposites were synthesised via hydrothermal and in situ assembly methods in varying weight percentages (5–25&#xa0;wt%) and systematically evaluated for mid-temperature thermoelectric applications. X-ray diffraction confirmed phase purity with characteristic peaks corresponding to orthorhombic Bi<sub>2</sub>S<sub>3</sub> and layered Ti<sub>3</sub>C<sub>2</sub>, while crystallite size analysis indicated optimal microstructural tuning at 15–20% BTG. Surface morphological investigations using FESEM revealed nanosheet-stacked layered architectures, and HR-TEM confirmed nanocrystalline domains with interfacial lattice fringes. Elemental analysis and mapping through EDS demonstrated homogeneous dispersion of Bi, Ti, S, C, and O across the composite. UV–vis DRS studies indicated that bandgap narrows from 1.61&#xa0;eV for pristine Ti<sub>3</sub>C<sub>2</sub> to 1.45&#xa0;eV for 20% Bi<sub>2</sub>S<sub>3</sub>–Graphene@Ti<sub>3</sub>C<sub>2</sub>, suggesting strong interfacial electronic interactions. Thermal analysis via TGA–DTA demonstrated excellent stability up to 500&#xa0;°C with minimal mass loss of 3%. Thermoelectric performance was assessed through detailed temperature-dependent transport measurements. Electrical conductivity increased with Bi<sub>2</sub>S<sub>3</sub>–Graphene@Ti<sub>3</sub>C<sub>2</sub> loading and temperature, reaching a maximum of 476.8 S/m at 573&#xa0;K for 20% Bi<sub>2</sub>S<sub>3</sub>–Graphene@Ti<sub>3</sub>C<sub>2</sub>. Hall measurements confirmed n-type conduction and revealed increased carrier transport efficiency of 275 cm<sup>2</sup>V<sup>−1</sup>&#xa0;S<sup>−1</sup> at intermediate compositions. Seebeck coefficient exhibited a maximum of − 35&#xa0;μV/K for 25% BTG, while the highest power factor of 0.458&#xa0;Wm<sup>−1</sup>&#xa0;K<sup>−2</sup> and figure-of-merit of zT 0.00011 were also obtained for the same sample at 573&#xa0;K. The decrease in thermal conductivity (<i>κ</i>) was primarily accredited to lattice phonon scattering at the heterogeneous interfaces. These results highlight the potential of Bi<sub>2</sub>S<sub>3</sub>–Graphene@Ti<sub>3</sub>C<sub>2</sub> nanocomposites as tunable thermoelectric materials, with interfacial engineering serving as a key strategy to enhance transport properties while maintaining thermal suppression.</p>

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Intercalation of Bi2S3–graphene into MXene nanosheets: a novel strategy for enhanced thermoelectric performance

  • 期刊论文

  • 发表日期：

    2025年8月1日

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  • R. B. Shivani,
  • J. Mani,
  • J. Balachandran,
  • Jasin Kasthuri,
  • R. Mohan Kumar

摘要

A series of Bi2S3–Graphene–Ti3C2 (BTG) nanocomposites were synthesised via hydrothermal and in situ assembly methods in varying weight percentages (5–25 wt%) and systematically evaluated for mid-temperature thermoelectric applications. X-ray diffraction confirmed phase purity with characteristic peaks corresponding to orthorhombic Bi2S3 and layered Ti3C2, while crystallite size analysis indicated optimal microstructural tuning at 15–20% BTG. Surface morphological investigations using FESEM revealed nanosheet-stacked layered architectures, and HR-TEM confirmed nanocrystalline domains with interfacial lattice fringes. Elemental analysis and mapping through EDS demonstrated homogeneous dispersion of Bi, Ti, S, C, and O across the composite. UV–vis DRS studies indicated that bandgap narrows from 1.61 eV for pristine Ti3C2 to 1.45 eV for 20% Bi2S3–Graphene@Ti3C2, suggesting strong interfacial electronic interactions. Thermal analysis via TGA–DTA demonstrated excellent stability up to 500 °C with minimal mass loss of 3%. Thermoelectric performance was assessed through detailed temperature-dependent transport measurements. Electrical conductivity increased with Bi2S3–Graphene@Ti3C2 loading and temperature, reaching a maximum of 476.8 S/m at 573 K for 20% Bi2S3–Graphene@Ti3C2. Hall measurements confirmed n-type conduction and revealed increased carrier transport efficiency of 275 cm2V−1 S−1 at intermediate compositions. Seebeck coefficient exhibited a maximum of − 35 μV/K for 25% BTG, while the highest power factor of 0.458 Wm−1 K−2 and figure-of-merit of zT 0.00011 were also obtained for the same sample at 573 K. The decrease in thermal conductivity (κ) was primarily accredited to lattice phonon scattering at the heterogeneous interfaces. These results highlight the potential of Bi2S3–Graphene@Ti3C2 nanocomposites as tunable thermoelectric materials, with interfacial engineering serving as a key strategy to enhance transport properties while maintaining thermal suppression.