Enhanced photocatalytic degradation of methylene blue and methyl green using iron doped zinc oxide nanoparticles impregnated with graphitic carbon nitride

Abstract

It is well known that the broadened light absorption ability of semiconductors and formation of heterojunction between them enhances their photocatalytic properties by decreasing the e⁻/h⁺ recombination. The graphitic carbon nitride (g-C₃N₄) along with embedded metal oxide nanoparticles is a very promising for this purpose. Moreover, the porous nature of graphitic carbon nitride helps in removal of organic pollutants from wastewater through adsorption of. Herein, the Zn_0.98Fe_0.02O nanoparticles which were synthesized by green synthesis route were embedded in graphitic carbon nitride to get Zn_0.98Fe_0.02O/g-C₃N₄ nanocomposite. The samples were characterized using different analytical techniques. The Zn_0.98Fe_0.02O, g-C₃N₄ and Zn_0.98Fe_0.02O/g-C₃N₄ exhibit a direct band gap E_g of 2.75 eV, 2.65 eV and 2.68 eV respectively. The adsorption and photocatalytic degradation activities against methylene blue (MB) and methyl green (MG) dyes using synthesized samples were studied by monitoring the removal of dyes under dark and visible light. It was found that the Zn_0.98Fe_0.02O/g-C₃N₄ nanocomposite showed good adsorption capacity of organic dyes due to its porous nature. Furthermore, the Zn_0.98Fe_0.02O/g-C₃N₄ nanocomposite depicted an excellent photocatalytic activity towards degradation of dyes and under solar irradiation. The Zn_0.98Fe_0.02O/g-C₃N₄ nanocomposite removed about 98% of MB and 95% of MG in just 60 min. The composite Zn_0.98Fe_0.02O/g-C₃N₄ shoed the highest rate constant values for the photocatalytic degradation of MB and MG which are 0.06094 and 0.0246 respectively. The formation of heterojunction between Zn_0.98Fe_0.02O and g-C₃N₄ generated the superoxide and hydroxyl radicals which elevated the degradation activity under light. Graphical abstract.

Graphical abstract