Facile construction of a fascinating dual Z-scheme Bi2S3/tg-C3N4/α-Ag2WO4 photocatalyst for effective removal of organic pollutants: Influence factors, mechanism insight and degradation pathway

• Published in: Journal of water process engineering 2023-02, Vol.51, p.103373, Article 103373
• Main Authors: Ayappan, Chinnadurai, Mani, Alagiri
• Format: Article
• Language: English
• Subjects: Bi2S3/tg-C3N4/α-Ag2WO4; Dual Z-scheme; Photocatalyst; Sunlight irradiation; TC antibiotic
• ISSN: 2214-7144; 2214-7144
• DOI: 10.1016/j.jwpe.2022.103373

Inefficient utilization of sunlight response, low separation of photoinduced charge carriers, narrow redox potential and inferior recycling capacity significantly affects the functionalities of catalyst to get access in the practical wastewater treatment. A novel dual Z-scheme Bi2S3/tg-C3N4/α-Ag2WO4 ternary nanocomposite was designed and fabricated successfully to improve the absorption range of sunlight. The structural, optical, morphological, compositional and nitrogen adsorption-desorption properties of as-prepared pristine, binary and ternary photocatalysts were examined comprehensively. The 15 % Bi2S3/tg-C3N4/α-Ag2WO4 ternary nanocomposite demonstrated the highest degradation efficiency for toxic pollutants such as TC antibiotic (η = 95.02 %), MB (η = 98.94 %), RhB (η = 99.26 %) and MO (η = 77.35 %) under sunlight irradiation. The optimized 15 % Bi2S3/tg-C3N4/α-Ag2WO4 photocatalyst exhibits the reaction rate constant of TC antibiotic (k = 0.0209 min−1) was 3.6, 6.7 and 1.8 folds higher than that of pristine 1D-α-Ag2WO4, 1D-Bi2S3 and 2D-tg-C3N4. The favorable photocatalytic performance of dual Z-scheme heterojunction is attributed to a tight contact interface, good redox potential capacity, higher separation of photogenerated electron-hole pairs and inferior charge carriers recombination rate. The recycling tests reveal the attractive reusability and photostability of 15 % Bi2S3/tg-C3N4/α-Ag2WO4 photocatalyst. Moreover, the quenching experiment suggested that the holes (h+) radical play a dominant role in the photocatalytic activity process of toxic contaminants over 15 % Bi2S3/tg-C3N4/α-Ag2WO4 ternary nanocomposite. The possible reaction mechanism and degradation pathways of TC antibiotic were speculated with several characteristic intermediates identified. This present work deals with new understanding of the design and construction of dual Z-scheme heterojunction photocatalysts for wastewater remediation in an environmental application. Mediator-free direct dual-Z-scheme Bi2S3/tg-C3N4/α-Ag2WO4 ternary photocatalysts were controllably synthesized by the hydrothermal method for the first time. The as-constructed Bi2S3/tg-C3N4/α-Ag2WO4 nanocomposites exhibited significantly improved photocatalytic activity for organic pollutants (TC = 95.02 %, MB = 98.94 %, RhB = 99.26 % and MO = 77.35 %) degradation compared to pristine 1D-α-Ag2WO4, 1D-Bi2S3, 2D-tg-C3N4 and 25 % tg-C3N4/α-Ag2WO4 binary photocatalysts, respectively. The possible photocatalytic degradat