Synthesis of GS-assisted Mn5O8 photocatalysts for efficient visible-light degradation of direct green 6 dye

Abstract

A facile and effective hydrothermal method incorporating a Gemini like surfactant with different molar concentrations was developed, and its photocatalytic activity toward Direct Green 6 (DG6) degradation was systematically evaluated for the first time. The crystal phase, optical behaviour, surface morphology, Microstructural analysis, Surface area & Porosity analysis, Composition & Oxidation states and absorption features were systematically examined using X-ray diffraction (XRD), UV-diffused reflectance spectra (UV–DRS), scanning electron microscopy (SEM), Transmission Electron Microscope (TEM), Brunauer-Emmett-Teller (BET), X-ray Photoelectron Spectroscopy (XPS) and Fourier transform infrared (FT-IR), respectively. The 0.05 M GS-assisted Mn₅O₈ (Gemini surfactant stabilized Mn₅O₈) photocatalyst exhibited superior performance compared to the other photocatalysts. The optimized GS-assisted Mn₅O₈ photocatalyst exhibited superior degradation efficiency of 97.6% within 75 min, with a high apparent rate constant (k = 0.0377s⁻¹), which is significantly higher than other Mn₅O₈ by improved charge separation, increased surface defects, and enhanced active site availability in Gemini surfactant whereas lower concentrations provide insufficient surface modification and higher concentrations lead to active site blockage. Moreover, the photocatalyst can be easily recovered and reused over multiple cycles, providing a simple and efficient approach for effective photocatalytic degradation of organic contaminants.

Graphical abstract