Visible light-driven photocatalytic degradation of fluoroquinolone drugs in water over plasmonic Ag/ZnNb2O6@SC3N4 indirect Z-scheme nanostructures

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Physicochemical and engineering aspects, 2023-10, Vol.674, p.131876, Article 131876
• Main Authors: Jones, Benjamin Moses Filip, Mamba, G., Maruthamani, D., Muthuraj, V.
• Format: Article
• Language: English
• Subjects: Ag/ZnNb2O6@SC3N4; Indirect Z-scheme; Levofloxacin; Ofloxacin; Photocatalysis
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2023.131876

The fabrication of visible light responsive heterojunction photocatalyst with efficient charge separation and transfer is an important quest in the exploitation of photocatalysis for environmental remediation. In this work, a ternary heterostructure comprising of zinc niobate (ZnNb2O6) coupled with sulphur-doped graphitic carbon nitride (SC3N4) and decorated with varying loadings of silver nanoparticles (Ag NPs) was obtained using ultrasonic synthesis. The photocatalysts were characterized extensively using various microscopic, spectroscopic, and electrochemical analytical techniques. The 5 wt%Ag/ZnNb2O6 @SC3N4 heterojunction showed the highest degradation efficiencies towards the antibiotic drugs; levofloxacin (LVF, 94.6 % removal) and ofloxacin (OFX, 98.0 % removal) in just 60 min of visible light irradiation. This activity is nearly 5 times and 3.5 times higher than that over ZnNb2O6 @SC3N4 for LVF and OFX, respectively, which indicates the importance of incorporating the Ag NPs towards better visible utilization, improved charge separation efficiency and lower charge transfer resistance. The influence of pH, photocatalyst dose and initial concentration of pollutant were investigated. Finally, a typical Ag NPs mediated indirect Z-Scheme charge transfer mechanism was proposed to describe the formation of the reactive species and subsequent degradation of the pollutants. This work demonstrates a systematic design of simple but efficient photocatalytic nanocomposites with the capability to ameliorate a wide variety of fluoroquinolone drugs, which is significant towards pharmaceutical pollution mitigation. [Display omitted] •Ag/ZnNb2O6 @SC3N4 obtained via ultrasonic treatment and chemical reduction.•Ternary composite with improved optical response and charge separation•LVF and OFX degradation predominantly mediated by h+, e- and •OH.•Ag NPs acted as electron shuttles in an indirect Z-scheme mechanism.•5 wt%Ag/ZnNb2O6 @SC3N4 attained over 90 % TOC removal for LVF and OFX.