Hybrid magnetic nanocomposite NiFe2O4/TiO2 for photocatalytic dye degradation and green hydrogen (H2) generation.

The present paper focuses on designing and developing nanocomposites to modify their properties to increase the ability to generate hydrogen and degrade dyes using photocatalysis. A nanocomposite of nickel ferrite (NiFe 2 O 4)/Titanium dioxide (TiO 2) was formulated using the sol-gel self-ignition method. X-ray diffraction (XRD) tool was adopted to analyze the structural behavior of pure nickel ferrite (NiFe 2 O 4), pure titanium dioxide (TiO 2), and nanocomposite of NiFe 2 O 4 /TiO 2. XRD pattern of NiFe 2 O 4 and TiO 2 shows a monophasic nature whereas the XRD pattern of nanocomposites shows mixed phases of NiFe 2 O 4 and TiO 2. FTIR spectra confirm the formation of NiFe 2 O 4 , TiO 2, and their composites with absorption bands near 400 cm−1 and 600 cm−1, 1500 cm−1. Raman spectra unveiled the presence of five active Raman modes in the case of NiFe 2 O 4 whereas three active Raman modes are seen in TiO 2. Field emission scanning electron microscopy (FE-SEM) images exposed the dense structure with spherical cluster-like morphology in the case of NiFe 2 O 4. Energy-dispersive X-ray spectroscopy (EDX) analysis confirms the presence of all the desired elements of NiFe 2 O 4 , TiO 2, and their composites in stoichiometric proportions. BET analysis of nickel ferrite NPs suggests a large surface area of the order of 31.54 m2/gm in comparison with TiO 2 (19.23 m2/gm). The optical characterization was made through the UV–visible spectroscopic technique. TiO 2 shows a maximum band gap of the order of 3.02 eV while NiFe 2 O 4 shows a low band gap of the order of 1.74 eV. A typical M − H curve with saturation magnetization of the order of 27.54 emu/gm was observed for pure NiFe 2 O 4. No magnetic properties were observed for TiO 2 as it is a semiconductor. Enhancement in magnetic properties is observed with increases in NiFe 2 O 4 content in a composite of NiFe 2 O 4 /TiO 2. The photocatalytic activities were examined by degrading Methylene Blue (MB) dye under sunlight for pure nickel ferrite (NiFe 2 O 4), pure titanium dioxide (TiO 2), and a nanocomposite of NiFe 2 O 4 /TiO 2. Photocatalytic hydrogen production reactions were carried out in a methanol/water solution under visible light. Consequently, the best configuration of the photocatalyst was determined as 25 % wt% NiFe2O4/TiO2 which had shown the maximum hydrogen (H2) production rate as 146.3 μmol/g/h after 8 h owing to its reduced bandgap energy and delayed e−/h+ recombination. [ABSTRACT FROM AUTHOR]