Effect of thermal behavior treatment and nickel doping impact on the structure, morphology and photocatalytic properties of NixZn1-xBi0.3Fe1.7/SiO2 nanocomposites

The present work shows the characterization of Ni_xZn_1-xBi_0.3Fe_1.7O₄ (x = 0–0.5) incorporated into a SiO₂ matrix, obtained by using a sol-gel method. The thermal analyses confirmed the development of Ni, Zn, Bi and Fe succinates at 131–190 °C and their transformation thorough decomposition into metal oxides at 260–314 °C, that subsequently undergo reactions to produce ferrites. The formation, development and decomposition of glyoxylate precursors, followed by their incorporation in the SiO₂ matrix and the formation of spinel ferrite were confirmed by infrared spectroscopy. The formation of Ni-Zn-Bi ferrites with crystallite sizes in the range of 49.1–98.6 nm was established by X-ray diffraction. At high heat treatment temperatures, crystalline ferrites were integrated into the crystalline phases of the SiO₂ matrix. At low heat treatment temperatures, poorly crystalline ferrites accompanied by silicates were formed. All the analyzed samples exhibit a certain degree of porosity. Mesoporous are present within a narrow pore size distribution. The photocatalytic performances of the samples investigated were evaluated by studying the degradation of Rhodamine B under the action of visible light. High amounts of Ni in the sample lead to the best removal performance, ~77%. Scavenger experiments confirm that in the photocatalytic processes involve holes, hydroxyl radicals and superoxide radicals. The photostability of the sample with Ni_0.5Zn_0.5Bi_0.3Fe_1.7O₄/SiO₂ was tested over five consecutive photocatalytic cycles.

Graphical Abstract