Bandgap tuning of photo Fenton-like Fe3O4/C catalyst through oxygen vacancies for advanced visible light photocatalysis

Abstract

Herein, low-cost Fe₃O₄/C nanocomposites have been prepared by a simplistic single-pot D-glucose-mediated hydrothermal reduction technique using a single iron precursor (FeCl₃·6H₂O) acquired from accumulated iron ore tailings. Two noticeably different samples having different crystallite sizes were fabricated by tuning the hydrothermal reduction method. To tune the hydrothermal reaction condition, two specifically different temperatures and reaction times were selected and a suitable justification has been provided for this selection. A qualitative rationalization for bandgap dependence on the crystallite size has been offered with the help of UV-visible differential reflectance spectroscopy (UV-DRS) and photoluminescence (PL) spectroscopy, which point to quantum confinement effects. Thermogravimetric analysis (TGA) data evidently quantify the total amount of carbon in the sample. X-ray photoelectron spectroscopy (XPS) and Rietveld analysis elucidate the dependence of crystallite size with the concentration of oxygen vacancy. The sample having adequate oxygen vacancies and favorable bandgap was established to be more efficient for the photodecomposition of Rhodamine B under visible light irradiation, which also outperformed standard TiO₂ (Degussa P-25) with tremendous recyclability and structural stability. Furthermore, the magnetization measurements illustrate the superparamagnetic behavior of the sample, which is also found to be dependent on the crystallite size.