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<p>Graphitic carbon nitride (g-C<sub>3</sub>N<sub>4</sub>)-based materials have emerged as photocatalysts with promising applications in the treatment of organic pollutants. In this study, silver nanoparticles and Fe<sub>3</sub>O<sub>4</sub> were immobilized onto stacked graphitic layers to fabricate the heterojunction structure Ag@Fe<sub>3</sub>O<sub>4</sub>/g-C<sub>3</sub>N<sub>4</sub> via photoreduction. The successful construction of Ag@Fe<sub>3</sub>O<sub>4</sub>/g-C<sub>3</sub>N<sub>4</sub> demonstrated excellent photocatalytic efficiency in the photoreduction of 10&#xa0;ppm 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) under visible light irradiation, achieving over 99.8% conversion of 4-NP to 4-AP within 300&#xa0;s in the presence of sodium borohydride. The photocatalytic efficiency decreased from 99.8 to 76.6% with increasing 4-NP concentration from 10 to 40&#xa0;ppm, respectively. The highest pH for photoreduction was found at 9, achieved 98.6%. The material was also assessed for its efficacy in the photodegradation of oxytetracycline (OTC), a prevalent antibiotic. The results showed that Ag@Fe<sub>3</sub>O<sub>4</sub>/g-C<sub>3</sub>N<sub>4</sub>, with greater light absorption under visible light irradiation, improved the production of e<sup>−</sup> and <sup>•</sup>OH radicals, which played an important role in the photocatalytic degradation of OTC at 15&#xa0;mg/L, achieving a removal efficiency of 98.0% within 120&#xa0;min. pH, initial&#xa0;OTC concentration, and catalytic dosage were among the factors investigated as influences on OTC photodegradation. Experimental results showed that increasing the initial OTC content from 15 to 50&#xa0;mg/L reduces photodegradation efficiency from 98.0 to 84.7%, respectively. With catalyst dosages ranging from 5 to 15&#xa0;mg, OTC photodegradation efficiency increases from 88.9 to 99.8%, respectively. As the pH decreases from 9.0 to 4.0, the degradation rate of OTC increased from 77.4 to 91.3% due to the increased production of <sup>•</sup>OH radicals in acidic environments. Notably, the Ag@Fe<sub>3</sub>O<sub>4</sub>/g-C<sub>3</sub>N<sub>4</sub> demonstrated outstanding reusability, with 79.5% efficiency remaining after four consecutive usage cycles. This thorough investigation presents a simple and reliable method for synthesizing photocatalytic Ag@Fe<sub>3</sub>O<sub>4</sub>/g-C<sub>3</sub>N<sub>4</sub> materials for reduction of 4-NP and photodegradation of OTC.</p>

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Photo-reduced synthesis of a Z-scheme Ag@Fe3O4/g-C3N4 composite for photoreduction of 4-nitrophenol and photocatalytic activity

  • 期刊论文

  • 发表日期：

    2025年2月6日

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  • Thi Hoang My Nguyen,
  • Van Cuong Nguyen,
  • Thi Hong Anh Nguyen

摘要

Graphitic carbon nitride (g-C3N4)-based materials have emerged as photocatalysts with promising applications in the treatment of organic pollutants. In this study, silver nanoparticles and Fe3O4 were immobilized onto stacked graphitic layers to fabricate the heterojunction structure Ag@Fe3O4/g-C3N4 via photoreduction. The successful construction of Ag@Fe3O4/g-C3N4 demonstrated excellent photocatalytic efficiency in the photoreduction of 10 ppm 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) under visible light irradiation, achieving over 99.8% conversion of 4-NP to 4-AP within 300 s in the presence of sodium borohydride. The photocatalytic efficiency decreased from 99.8 to 76.6% with increasing 4-NP concentration from 10 to 40 ppm, respectively. The highest pH for photoreduction was found at 9, achieved 98.6%. The material was also assessed for its efficacy in the photodegradation of oxytetracycline (OTC), a prevalent antibiotic. The results showed that Ag@Fe3O4/g-C3N4, with greater light absorption under visible light irradiation, improved the production of e− and •OH radicals, which played an important role in the photocatalytic degradation of OTC at 15 mg/L, achieving a removal efficiency of 98.0% within 120 min. pH, initial OTC concentration, and catalytic dosage were among the factors investigated as influences on OTC photodegradation. Experimental results showed that increasing the initial OTC content from 15 to 50 mg/L reduces photodegradation efficiency from 98.0 to 84.7%, respectively. With catalyst dosages ranging from 5 to 15 mg, OTC photodegradation efficiency increases from 88.9 to 99.8%, respectively. As the pH decreases from 9.0 to 4.0, the degradation rate of OTC increased from 77.4 to 91.3% due to the increased production of •OH radicals in acidic environments. Notably, the Ag@Fe3O4/g-C3N4 demonstrated outstanding reusability, with 79.5% efficiency remaining after four consecutive usage cycles. This thorough investigation presents a simple and reliable method for synthesizing photocatalytic Ag@Fe3O4/g-C3N4 materials for reduction of 4-NP and photodegradation of OTC.