Properties of CuFeS2/TiO2 Nanocomposite Prepared by Mechanochemical Synthesis

Abstract

CuFeS2/TiO2 nanocomposite has been prepared by a simple, low-cost mechanochemical route to assess its visible-light-driven photocatalytic efficiency in Methyl Orange azo dye decolorization. The structural and microstructural characterization was studied using X-ray diffraction and high-resolution transmission electron microscopy. The presence of both components in the composite and a partial anatase-to-rutile phase transformation was proven by X-ray diffraction. Both components exhibit crystallite size below 10 nm. The crystallite size of both phases in the range of 10–20 nm was found and confirmed by TEM. Surface and morphological properties were characterized by scanning electron microscopy and nitrogen adsorption measurement. Scanning electron microscopy has shown that the nanoparticles are agglomerated into larger grains. The specific surface area of the nanocomposite was determined to be 21.2 m2·g−1. Optical properties using UV-Vis and photoluminescence spectroscopy were also investigated. CuFeS2/TiO2 nanocomposite exhibits strong absorption with the determined optical band gap 2.75 eV. Electron paramagnetic resonance analysis has found two types of paramagnetic ions in the nanocomposite. Mössbauer spectra showed the existence of antiferromagnetic and paramagnetic spin structure in the nanocomposite. The CuFeS2/TiO2 nanocomposite showed the highest discoloration activity with a MO conversion of ~ 74% after 120 min irradiation. This study has shown the possibility to prepare nanocomposite material with enhanced photocatalytic activity of decoloration of MO in the visible range by an environmentally friendly manner

Plasmon-Induced Polarity Inversion of Magnetic Circular Dichroism (MCD) Responses of Cu–Fe–S Bornite Nanodots upon Oxidation

“…Unfortunately, we could not obtain well-resolved Fe 2p-level XPS spectra probably because of the small fraction of Fe in these samples. According to the spectra, the Cu state did not change upon oxidation; in detail, the spectra showed a 2p 3/2 peak around 932.5 eV for both the oxidized and as-synthesized samples, which matches well with spectra for Cu­(I) . Additionally, neither spectrum contains the strong signature of Cu­(II) satellite peaks between 940 and 942 eV, confirming that the copper in bornite is still in the Cu­(I) monovalent state .…”

“…According to the spectra, the Cu state did not change upon oxidation; in detail, the spectra showed a 2p 3/2 peak around 932.5 eV for both the oxidized and as-synthesized samples, which matches well with spectra for Cu(I). 31 Additionally, neither spectrum contains the strong signature of Cu(II) satellite peaks between 940 and 942 eV, confirming that the copper in bornite is still in the Cu(I) monovalent state. 32 On the other hand, sulfur exhibited a significantly modified spectrum upon oxidation.…”

“…Then the signals can reasonably be ascribed to Fe­(III), not to Cu­(II) . Such a broad EPR signal should stem from strong interactions between the concentrated Fe 3+ spins, that is, like Fe 2 O 3 -type clusters of Fe­(III) ions. , Most notably, the EPR signal amplitudes of oxidized bornite BN 3/1 and BN 5/1 are much larger than those of the corresponding as-synthesized samples, meaning that the EPR signal enhancement can be due to the (released) Fe­(III) ions that are in a different environment (or coordination) from the bornite lattices. In other words, EPR is sensitive enough to effectively detect the slight leaching (or moving) of Fe­(III) ions from some nanostructured materials such as bornite upon oxidation.…”

Optical and Optoelectrical Properties of Ternary Chalcogenide CuInS2/TiO2 Nanocomposite Prepared by Mechanochemical Synthesis

“…A tungsten carbide milling chamber (volume 250 mL) filled with 50 balls (diameter 10 mm) of the same material was used for milling, and the milling was carried out at 550 rpm for 60 min in an argon atmosphere according to Equation (1) and the procedure provided in [18]. Mechanochemically prepared CuInS 2 according to Equation (1) and commercially available TiO 2 were used to synthesize the CuInS 2 /TiO 2 nanocomposite (Equation ( 2)) (in molar ratios of 4:1 and 1:4 chosen based on our results published in papers [16,17] for similar nanocomposites). The synthetic process of the CuInS 2 /TiO 2 nanocomposite is displayed in Figure 1 and can be described by the following reactions:…”

“…Its eco-friendly process means that synthesis takes place in the absence of solvents and toxic organometallic precursors and unwanted side-products. We have already prepared other metal sulfidebased semiconductor-TiO 2 nanocomposites via mechanochemical synthesis in the past [16,17].…”