A visible light-driven NaTiO3/g-C3N4 heterojunction photocatalyst for ultra-fast organic dye degradation

Abstract

Most conventional dye treatment methods have limited efficacy as they are expensive, time-intensive and result in incomplete dye removal from water. Addressing these issues, this work reports the fabrication of a NaTiO₃/g-C₃N₄ heterojunction photocatalyst, which was utilized for the advanced oxidation process under sunlight irradiation to remove crystal violet (CV) and methylene blue (MB) dyes and their binary mixture. The perovskite NaTiO₃ is synthesized via a simple hydrothermal method and combined with graphitic carbon nitride, formed through the thermal decomposition of melamine, to fabricate the heterojunction. The scanning electron microscopy (SEM) images reveal that spherical NaTiO₃ nanoparticles are aggregated on the sheet-like surface of g-C₃N₄ and structural analysis utilizing the XRD pattern confirms the formation of a heterojunction. From the Tauc plot the bandgap of the material is estimated to be 2.3 eV. The complete degradation of MB was observed within 25 min, while CV and the binary mixture require 20 min for complete degradation. The high visible light absorption of NaTiO₃ and large surface area of g-C₃N₄ were attributed to the enhanced catalytic performance of the heterojunction. Additionally, scavenger studies indicated that the radical species h⁺ and ˙OH played a crucial role in the photocatalytic degradation of the dyes. Reusability studies confirm good stability up to five cycles of dye degradation. The results establish the NaTiO₃/g-C₃N₄ heterojunction as an efficient photocatalyst to remove organic dyes from water, thus having immense potential in water purification.