Enhanced photocatalytic efficiency of hydrothermally synthesized g-C3N4/NiO heterostructure for mineralization of malachite green dye

Abstract

In this article, the photocatalytic performance of the heterostructure g-C3N4/NiO for the mineralization of the malachite green (MG) dye under the exposure of the UV light in an aqueous medium was characterized. The first part of the study was devoted to the synthesis of the heterostructured nanocomposite by single-step hydrothermal process accompanied by calcination. Physical and chemical behaviour of the synthesized photocatalyst was examined by a high-resolution powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Transmission electron microscope (TEM), Field emission scanning electron microscope (FESEM), Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS) measurements. TEM and XRD measurements confirms the formation of the heterostructured hexagonal shaped g-C3N4/NiO. The structural stability of the nanocomposite photocatalyst was analysed by XRD measurment after the recyclability test. XPS analysis disclosed the oxidation state of the nickel (Ni+2) into the photocatalyst. The superiority of our synthesized catalyst is that the better optical band gap matching and the fact that it regulates internal charge transfer of excitons within the heterojunction. Second part of the study focused on the degradation of the MG with nanocomposite g-C3N4/NiO. Scavenger analysis revealed the existence of the superoxide radicals (O2•-) as the main active species, which is the caretaker of mineralization of the MG with the nanocomposite that have one of the highest turn over frequency (TOF) till date.