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<p>This study investigates the synthesis and photocatalytic performance of a biphasic TiO<sub>2</sub>/ZIF-8 nanocomposite produced via a co-precipitation method. The structure and morphology of nanocomposite were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HR-TEM). The photo absorption properties of the samples were measured using a UV–Visible diffuse reflectance spectroscopy. BET analysis showed that the TiO<sub>2</sub>/ZIF-8 nanocomposite exhibited a significantly higher specific surface area (209.07 m<sup>2</sup>g<sup>− 1</sup>) compared to pure TiO<sub>2</sub> (66.17 m<sup>2</sup>g<sup>− 1</sup>). The vibrational bands of the materials were investigated by Fourier transform Infrared spectroscopy (FT-IR). The reduction in charge recombination in the nanocomposite was confirmed by the photoluminescence (PL) spectra. Notably, the TiO<sub>2</sub>/ZIF-8 nanocomposite exhibited significantly improved photocatalytic activity for methylene blue (MB) degradation under sunlight compared with pure TiO<sub>2</sub> and ZIF-8. A maximum degradation efficiency of 98.95% and a high-rate constant of 0.0362&#xa0;min<sup>− 1</sup> were achieved under natural sunlight illumination owing to the accelerated charge transfer efficiency of the porous ZIF-8 catalyst. The nanocomposite exhibited a significantly higher apparent quantum yield (5.814%), indicating more efficient MB degradation under sunlight irradiation compared to that under UV or dark conditions. Radical scavenging experiments revealed that photogenerated electrons and superoxide radicals (•O<sub>2</sub>⁻) played a significant role in the photodegradation of MB. In addition, the TiO<sub>2</sub>/ZIF-8 nanocomposite demonstrated excellent stability, maintaining its photocatalytic performance over five consecutive cycles with no significant loss in efficiency. The presence of degradation intermediates were identified using LC–MS/MS analysis. Electrochemical analyses, such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), revealed that TiO<sub>2</sub>/ZIF-8 nanocomposites exhibit reduced charge transfer resistance compared to TiO<sub>2</sub> and ZIF-8 alone. Furthermore, these nanocomposites showed enhanced current responses and remarkable electrochemical stability, underscoring their promise as effective materials for photocatalytic and environmental remediation purposes. This research underscores the potential of TiO<sub>2</sub>/ZIF-8 nanocomposite as a highly effective photocatalyst for the degradation of organic pollutants using natural sunlight.</p>

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Biphasic TiO2/ZIF-8 Nanocomposite with Accelerated Charge Transfer for Enhanced Sunlight-Driven Photocatalytic Degradation of Methylene Blue

  • 期刊论文

  • 发表日期：

    2026年4月1日

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  • M. S. Monisha,
  • R. Sreeja

摘要

This study investigates the synthesis and photocatalytic performance of a biphasic TiO2/ZIF-8 nanocomposite produced via a co-precipitation method. The structure and morphology of nanocomposite were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HR-TEM). The photo absorption properties of the samples were measured using a UV–Visible diffuse reflectance spectroscopy. BET analysis showed that the TiO2/ZIF-8 nanocomposite exhibited a significantly higher specific surface area (209.07 m2g− 1) compared to pure TiO2 (66.17 m2g− 1). The vibrational bands of the materials were investigated by Fourier transform Infrared spectroscopy (FT-IR). The reduction in charge recombination in the nanocomposite was confirmed by the photoluminescence (PL) spectra. Notably, the TiO2/ZIF-8 nanocomposite exhibited significantly improved photocatalytic activity for methylene blue (MB) degradation under sunlight compared with pure TiO2 and ZIF-8. A maximum degradation efficiency of 98.95% and a high-rate constant of 0.0362 min− 1 were achieved under natural sunlight illumination owing to the accelerated charge transfer efficiency of the porous ZIF-8 catalyst. The nanocomposite exhibited a significantly higher apparent quantum yield (5.814%), indicating more efficient MB degradation under sunlight irradiation compared to that under UV or dark conditions. Radical scavenging experiments revealed that photogenerated electrons and superoxide radicals (•O2⁻) played a significant role in the photodegradation of MB. In addition, the TiO2/ZIF-8 nanocomposite demonstrated excellent stability, maintaining its photocatalytic performance over five consecutive cycles with no significant loss in efficiency. The presence of degradation intermediates were identified using LC–MS/MS analysis. Electrochemical analyses, such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), revealed that TiO2/ZIF-8 nanocomposites exhibit reduced charge transfer resistance compared to TiO2 and ZIF-8 alone. Furthermore, these nanocomposites showed enhanced current responses and remarkable electrochemical stability, underscoring their promise as effective materials for photocatalytic and environmental remediation purposes. This research underscores the potential of TiO2/ZIF-8 nanocomposite as a highly effective photocatalyst for the degradation of organic pollutants using natural sunlight.