Facile Synthesis of Rice Husk Derived SiO 2 /g‐C 3 N 4 Heterostructures for Enhanced Photocatalyt
A. Janaki Ramya, Vinothkumar Arumugam, V. Loganathan, S. KumaranABSTRACT
In this work, SiO 2 /g‐C 3 N 4 photocatalyst was prepared using rice‐husk‐derived silica (SiO 2 ‐RH) and urea‐derived g‐C 3 N 4 by a simple calcination method. The SiO 2 /g‐C 3 N 4 composites were prepared with different g‐C 3 N 4 loadings (20, 25, and 30 wt%) and analyzed for visible‐light degradation of methylene blue (MB) and ciprofloxacin (CIP). X‐ray diffraction (XRD) results confirmed the presence of amorphous SiO 2 and the intact g‐C 3 N 4 structure. UV–vis DRS results showed that the band gap decreased from 3.25 eV (g‐C 3 N 4 ) to 2.81 XRD results confirmed predominantly amorphous rice‐husk‐derived SiO 2 together with the characteristic g‐C 3 N 4 structure. eV (SiO 2 ‐CN25). Photoluminescence (PL) results, photocurrent (7.6 µA cm −2 ) and EIS ( R ct = 28.7 Ω cm 2 ) confirmed better charge transfer and lower electron–hole recombination. Textural analysis showed a large surface area of 168.3 m 2 g −1 and mesopores (8–10 nm) for SiO 2 ‐CN25. Under visible light ( λ > 420 nm), SiO 2 ‐CN25 degraded 94% of MB and 89% of CIP in 90 min, with rate constants of 0.031 and 0.027 min −1 . The optimized SiO 2 ‐CN25 also showed good stability, retaining 90% of its initial photocatalytic activity after five consecutive reuse cycle 2.8s. The biomass‐derived, metal‐free SiO 2 ‐CN25 shows high efficiency, stability and eco‐friendliness for visible‐light wastewater treatment.