Novel g‐C3N4 nanosheets/CDs/BiOCl photocatalysts with exceptional activity under visible light

• Published in: Journal of the American Ceramic Society Vol. 102; no. 3; pp. 1435 - 1453
• Main Authors: Asadzadeh‐Khaneghah, Soheila, Habibi‐Yangjeh, Aziz, Yubuta, Kunio
• Format: Journal Article
• Language: English
• Published: Columbus Wiley Subscription Services, Inc 01.03.2019
• Subjects: Carbon dots; Carbon nitride; Catalytic activity; Cr (VI) photoreduction; Gas chromatography; g‐C3N4 nanosheet/C‐dots/BiOCl; Morphology; Nanocomposites; Nanosheets; Optical properties; Organic chemistry; Phenols; Photocatalysis; Photocatalysts; photocatalytic degradation; Photochemistry; Pollutants; Recyclability; Thermodynamic properties; visible‐light‐driven photocatalysts; X ray photoelectron spectroscopy
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/jace.15959

We fabricated novel ternary nanocomposites through integration of C‐dots (carbon dots), BiOCl, and nanosheets of graphitic carbon nitride (g‐C3N4 nanosheets) by a cost‐effective route. The fabricated photocatalysts were subsequently characterized by XRD, EDX, TEM, HRTEM, XPS, FT‐IR, UV‐vis DRS, TGA, BET, and PL methods to gain their structure, purity, morphology, optical, textural, and thermal properties. In addition, the degradation intermediates were identified by gas chromatography‐mass spectroscopy (GC‐MS). Photocatalytic performance of the synthesized samples was studied by photodegradations of three cationic (RhB, MB, and fuchsine), one anionic (MO) dyes, one colorless (phenol) pollutant and removal of an inorganic pollutant (Cr(VI)) under visible light. It was revealed that the ternary nanocomposite with loading 20% of BiOCl illustrated superlative performances in the selected photocatalytic reactions compared with the corresponding bare and binary photocatalysts. Visible‐light photocatalytic activity of the g‐C3N4 nanosheets/CDs/BiOCl (20%) nanocomposite was 42.6, 27.8, 24.8, 20.2, and 15.9 times higher than the pure g‐C3N4 for removal of RhB, MB, MO, fuchsine, and phenol, respectively. Likewise, the ternary photocatalyst showed enhanced activity of 15.3 times relative to the g‐C3N4 in photoreduction of Cr(VI). Moreover, the ternary nanocomposite exhibited excellent chemical stability and recyclability after five cycles. Finally, the mechanism for improved photocatalytic performance was discussed based on the band potential positions. To effectively utilize sunlight as a light source in photocatalytic processes, it is urgently necessary to fabricate more efficient visible‐light‐driven photocatalysts. Numerous researches have been recently directed towards applications of graphitic carbon nitride (g‐C3N4) as photocatalyst. However, large scale applications of this photocatalyst hindered by several shortcomings of serious recombination of the photoinduced charges, poor electrical conductivity, smaller specific surface area, and poor visible‐light absorption. In the present work, texture modification was applied to increase specific surface of g‐C3N4. In addition, BiOCl was selected to suppress recombination of the electron/hole pairs, because of its appropriate conduction band and valence band potentials. Moreover, carbon dots (CDs) were deposited over g‐C3N4 nanosheets to greatly facilitate transfer of electrons from the CB of g‐C3N4 nanosheets to that of BiOCl. Thus, the fabricated novel g‐C3N4 nanosheets/CDs/BiOCl nanocomposites exhibited highly improved photocatalytic activity. The ternary nanocomposite with 20% of BiOCl exhibited superior photocatalytic performance in degradations of four organic pollutants including RhB, MB, MO, and fuchsine when compared with the corresponding binary photocatalysts and bulk g‐C3N4. Also, the ternary nanocomposite displayed supreme photoactivity in reduction of Cr(VI) under visible light. In the last section, the possible enhanced photocatalytic mechanism as well as the reusability and stability of the photocatalyst were also described.