Different Fuel-Adopted Combustion Syntheses of Nano-Structured NiCrFeO₄: A Highly Recyclable and Versatile Catalyst for Reduction of Nitroarenes at Room Temperature and Photocatalytic Degradation of Various Organic Dyes in Unitary and Ternary Solutions

Abstract

As industrialization progresses, there is a large release of hazardous pollutants into the environment. These pollutants, which contain nitro compounds and organic dyes, are extremely dangerous due to their toxic and carcinogenic nature. An efficient, environmentally benign, and economical catalyst to degrade environmental pollutants or convert them into useful products has been of sustained interest in recent years. In this context, we report a simple and inexpensive combustion fabrication of NiCrFeO 4 using different fuels such as glycine, polyvinyl alcohol (PVA), and urea, showing tremendous catalytic and photocatalytic functionalities. Rietveld refinement and X-ray diffraction studies confirmed the formation of single-phase ferrites, with crystallite sizes ranging from 3.9 to 43.31 nm. The values of optical band gap, obtained from the diffused reflectance spectroscopy technique, lie in the visible region range (1.50–1.60 eV), and hence, all the synthesized ferrites can act as good photocatalysts in the presence of visible light. All the NCF nanocatalysts were utilized for the reduction of nitroarenes and photocatalytic degradation of various cationic (RhB and MB) and anionic (MO) dyes and their mixture. NCFP displayed excellent activity for the reduction and oxidation reactions owing to its large surface area and low optical band gap. Furthermore, the photo-oxidative degradation by NCFP was also enhanced due to its low recombination of charge carriers as confirmed by the photoluminescence (PL) spectroscopy. NCFP efficiently reduces nitrobenzene to aminobenzene with 95% yield using sodium borohydride as the reducing agent in methanol medium at RT in 10 min. The results of photocatalytic activity have shown that the degradation efficiency of NCFP follows the order RhB > MB > MO in their unitary solution. Furthermore, in the case of the mixture of dyes, NCFP showed enhanced photocatalytic degradation for cationic dyes (RhB and MB) compared to that of anionic dye (MO). From the performance point of view, this catalyst can be useful in industrial application because of its high stability, greater catalytic efficiency, and cost-effectiveness.

New Rare Earth-Doped Bilayered Perovskite Oxide Photocatalysts Sr2La0.5R0.5FeMnO7 (R = La, Nd, Sm, Gd, Dy) for the Degradation of Highly Toxic Methylene Blue Dye in Wastewater under Visible Light: Structural, Optical, and Magnetic Properties

“…The relationship between the band gap value and the photon energy with the absorption coefficient is given by Tauc theory using the equation α normalh ν = A false( normalh ν − E g false) n where A is a proportionality constant, h is Planck’s constant, ν the photon’s frequency, and n is a constant denoting the type of electronic transition.…”

Solvent-Free Combustion-Assisted Synthesis of LaFe0.5Cr0.5O3 Nanostructures for Excellent Photocatalytic Performance toward Water Decontamination: The Effect of Fuel on Structural, Magnetic, and Photocatalytic Properties

“…The cationic dyes MB (98% in 60 min of irradiation) and RhB (99% in 60 min) have degraded faster than the anionic dye MO (60% in 60 min of irradiation). Since LFCO-U is electron-rich, it may attract cationic dye molecules, while repelling anionic dye molecules, and causes fast photodegradation of cationic dyes . The difference in the photodegradation of these dyes may be due to their different molecular structures .…”

“…Since LFCO-U is electron-rich, it may attract cationic dye molecules, while repelling anionic dye molecules, and causes fast photodegradation of cationic dyes. 50 The difference in the photodegradation of these dyes may be due to their different molecular structures. 88 Based on the reports, 89 , 90 the RhB degradation process begins with an N-de-ethylation and breakdown of the chromophore.…”

“…Among perovskite oxides, LaFeO 3 is one of the most studied perovskite oxides in the field of photocatalysis, owing to its high stability, nontoxicity, and suitable band gap energy values that lie in the range of visible light. The photocatalytic activity of LaFeO 3 can further be improved by doping Cr 3+ at the Fe 3+ site, as Cr 3+ promotes conversion of Fe 3+ to Fe 2+ and eventually, Fe 2+ causes a photo-Fenton-type reaction, which is responsible for photodegradation . In addition to this, LaFeO 3 possesses an antiferromagnetic character due to Fe 3+ –O–Fe 3+ interactions and Cr 3+ substitution at the Fe site can introduce Fe 3+ –O–Cr 3+ double-exchange ferromagnetic interactions, thereby causing a drastic change in magnetic properties.…”

“…The photocatalytic activity of LaFeO 3 can further be improved by doping Cr 3+ at the Fe 3+ site, as Cr 3+ promotes conversion of Fe 3+ to Fe 2+ and eventually, Fe 2+ causes a photo-Fenton-type reaction, which is responsible for photodegradation. 50 In addition to this, LaFeO 3 possesses an antiferromagnetic character due to Fe 3+ –O–Fe 3+ interactions and Cr 3+ substitution at the Fe site can introduce Fe 3+ –O–Cr 3+ double-exchange ferromagnetic interactions, thereby causing a drastic change in magnetic properties. In view of this, we have synthesized nanocrystalline Cr-doped lanthanum orthoferrite LaFe 0.5 Cr 0.5 O 3 by a combustion method using different fuels because it is a simpler process, yielding pure products, and significantly saves time and energy consumption over traditional methods.…”