Z-scheme CuFe2O4–TiO2 nanocomposite microspheres for the photodegradation of methylene blue

Hollow Nanospheres Organized by Ultra-Small CuFe2O4/C Subunits with Efficient Photo-Fenton-like Performance for Antibiotic Degradation and Cr(VI) Reduction

Hollow transition metal oxides have important applications in the degradation of organic pollutants by a photo-Fenton-like process. Herein, uniform, highly dispersible hollow CuFe2O4/C nanospheres (denoted as CFO/C-PNSs) were prepared by a one-pot approach. Scanning electron microscope (SEM) and transmission electron microscope (TEM) images verified that the CFO/C-PNS catalyst mainly presents hollow nanosphere morphology with a diameter of 250 ± 30 nm. Surprisingly, the photodegradation test results revealed that CFO/C-PNSs had an excellent photocatalytic performance in the elimination of various organic contaminants under visible light through the efficient Fenton catalytic process. Due to the unique hollow structure formed by the assembly of ultra-small CFO/C subunits, the catalyst exposes more reaction sites, improving its photocatalytic activity. More importantly, the resulting magnetically separable CFO/C-PNSs exhibited excellent stability. Finally, the possible photocatalytic reaction mechanism of the CFO/C-PNSs was proposed, which enables us to have a clearer understanding of the photo-Fenton mechanism. Through a series of characterization and analysis of degradation behavior of CFO/C-PNS samples over antibiotic degradation and Cr(VI) reduction, •OH radicals generated from H2O2 decomposition played an essential role in enhancing the reaction efficiency. The present work offered a convenient method to fabricate hollow transition metal oxides, which provided impetus for further development in environmental and energy applications. Highlights: Novel hollow CuFe2O4/C nanospheres were prepared by a facile and cost-effective method. CuFe2O4/C exhibited excellent photo-Fenton-like performance for antibiotic degradation. Outstanding photocatalytic performance was attributed to the specific hollow cavity-porous structure. A possible mechanism for H2O2 activation over hollow CuFe2O4/C nanospheres was detailed and discussed.

Hydrothermal synthesis of novel heterostructured Ag/TiO2 /CuFe2 O4 nanocomposite: Characterization, enhanced photocatalytic degradation of methylene blue dye, and efficient antibacterial studies

In this work, we reported the successful synthesis of novel Ag/TiO₂ /CuFe₂ O₄ ternary nanocomposite by hydrothermal technique by using TiO₂ /CuFe₂ O₄ binary nanocomposite precursor that was also prepared by hydrothermal treatment by using TiO₂ nanoparticles and CuFe₂ O₄ nanoparticles synthesized via sol-gel method. The synthesized nanomaterials were accessed for their morphological, structural, and optical properties. X-ray diffraction (XRD) study reveals the formation of pure Ag/TiO₂ /CuFe₂ O₄ ternary nanocomposite in which the Ag, TiO₂ , and CuFe₂ O₄ are in anatase, spinal, and cubic crystal phases, respectively. Transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) analyses of Ag/TiO₂ /CuFe₂ O₄ ternary nanocomposite indicated granule-shaped morphology with bright spots of silver. The existence of Ti, O, Cu, Fe, and Ag without any other elements in the energy-dispersive X-ray spectroscopy (EDS) spectra of the prepared ternary nanocomposite depict its purity and its polycrystalline nature was confirmed by its selected area electron diffraction (SAED) pattern. The ternary nanocomposite was utilized for the methylene blue dye degradation with an optimum dose of 1.00 g/100 ml under ultraviolet (UV) light; the enhanced photocatalytic activity of the composite is attributed mainly due to the appreciable magnitudinal difference of positive charge of the valence band and negative charge of the conduction band of TiO₂ and CuFe₂ O₄ ; meanwhile, the interfacially placed Ag acts as a sink for the elections. Also, the ternary nanocomposite showed satisfactory antibacterial activities. PRACTITIONER POINTS: The prepared ternary nanocomposite showed effective results in dye degradation and satisfactory antibacterial property. The concentration of methylene dye has decreased considerably in every degradation process which was accessed through UV-vis studies. The highest degradation by using the ternary nanocomposite archived at pH = 6 Appreciable antibacterial activity was achieved against a few Gram-positive strains and Gram-negative strains of bacteria. This research activity can open a broad area of research towards textile dye degradation and antibacterial studies.

Interfacial modification and band modulation for dramatically boosted photocatalytic hydrogen evolution

Interfacial modification and band modulation to narrow the band gap and improve light-harvesting ability of TiO₂ are promising strategies to dramatically promote photocatalytic activity. Herein, efficient Co(OH)₂-TiO₂ nanocomposites were reasonably designed and constructed by a facile room temperature solid-state synthetic strategy for interfacial modification and matched band gap to achieve the conversion of solar energy to hydrogen. Modifying transition metal hydroxide Co(OH)₂ on commercial TiO₂ can effectively narrow the band gap and accelerate the separation and migration of photo-induced carriers, which will extend light absorption range and facilitate more electrons transferring to the surface of photocatalyst, therefore the reducibility of photocatalysts is enhanced. The modified photocatalyst exhibits high photocatalytic hydrogen evolution activity and stability. Specifically, the obtained TCO-0.6 shows excellent photocatalytic hydrogen evolution rate of 21343.01 μmol g^-1 and is 23 times superior to commercial TiO₂. This work not only emphasizes a facile strategy for interfacial modification and band modulation under mild condition, but also provides a novel avenue for improving the performance of photocatalytic hydrogen evolution.

Fabrication of black TiO2-x /NiFe2O4 supported on diatomaceous earth with enhanced sonocatalytic activity for ibuprofen mitigation

This study reports a facile fabrication of black TiO_2-x /NiFe₂O₄ (Ti³⁺ self-doped titania coupled with nickel ferrite), an efficient sonocatalyst for ibuprofen (IBP) mitigation. Compared with TiO_2-x or NiFe₂O₄, TiO_2-x /NiFe₂O₄ heterojunction displayed higher sonocatalytic activity, and their immobilization onto diatomaceous earth further enhanced mitigation efficiency due to the synergy between adsorption and sonocatalysis. About 96.7% of 10 mg l^-1 IBP was removed in 100 min using 0.7 g l^-1 catalyst at pH = 6, with the ultrasonic power of 144 W and frequency of 60 KHz. Quenching experiment results demonstrated the roles of reactive species. The intermediates during IBP sono-oxidation were determined by HPLC-MS method, and the acute toxicity was evaluated. Furthermore, the reaction mechanism was proposed. The sonocatalyst revealed excellent reusability, suggesting itself promising for wastewater treatment.

Fabrication of black TiO2−x/CuFe2O4 decorated on diatomaceous earth with enhanced sonocatalytic activity for ibuprofen mitigation

This study reports facile fabrication of black TiO_2−x/CuFe₂O₄ (Ti³⁺ self-doped titania coupled with copper ferrite), an efficient sonocatalyst for ibuprofen (IBP) mitigation.