Highly dispersed FeOOH to enhance photocatalytic activity of TiO2 for complete mineralisation of herbicides

Abstract

Although there were many new photocatalysts reported recently, TiO2 has still been considered as one of the best candidates for real application of environmental decontamination. Fe-based oxides were synthesised as efficient and equally important non-toxic active species to improve the efficiency of TiO2 photocatalysts. Such nano-architectured FeOx/TiO2 was tested for herbicides mineralisation e.g. 2,4,6-trichlorophenol (2,4,6-TCP) and 2,4-dichlorophenoxyacetic 2 acid (2,4-D) under full arc light irradiation. The consistent results were achieved by HPLC, TOC and UV-vis spectra measurements, which show among three Fe species, Fe4NO3(OH)11, FeOOH and Fe2O3, FeOOH is the best to improve TiO2 activity. This active specie of FeOOH was readily controlled by synthesis temperature and precursor concentration, leading to 250 o C being the optimum temperature for the synthesis of very stable FeOOH/TiO2 nanocomposite with excellent photocatalytic activity, representing nearly two times activity of the benchmark PC50 TiO2 photocatalyst for all herbicides tested. Such high activity was attributed to the enhanced photo-generated electron-hole separation and improved generation of hydroxyl radicals by FeOOH. The multifunction of FeOOH is very crucial for organic pollutants mineralisation. The mechanistic studies also show that degradation of 2,4,6-TCP was mostly dominated by hydroxyl radicals and superoxide radicals. The possible degradation pathway of 2,4,6-TCP was also proposed.

Bimetallic FeOx–MOx Loaded TiO2 (M = Cu, Co) Nanocomposite Photocatalysts for Complete Mineralization of Herbicides

“…A modified surface impregnation and drying technique was used to prepare dual cocatalyst-decorated TiO 2 composites. , In a typical experiment, the appropriate percentage weight of the nitrate precursors of Fe­(III), Cu­(II), and Co­(II) was separately added to an aqueous suspension of 1.0 g of commercial PC50 TiO 2 under mild stirring, with M/TiO 2 composition (M is the metal with a weight percentage of 0.05, 0.1 and 0.5). The obtained slurry was continuously stirred with a magnetic stirrer bar and dried slowly at 80 °C on a hot plate.…”

“…Surface modification of TiO 2 with earth-abundant cocatalysts, such as iron, copper, and cobalt oxides, to enhance photocatalytic degradation of chlorinated herbicides, has been widely reported in the literature. − Unlike the widely reported codoping of TiO 2 with Fe and/or Cu as dopants, − the use of binary cocatalysts on surface modification of TiO 2 for photocatalytic water treatment was relatively less reported. A binary codeposition of Ag and Cu nanoparticles on TiO 2 , prepared via photodeposition, was reported for photocatalytic degradation of methylene blue dye and salicylic acid under UV and visible light irradiation .…”

“…Moreover, the development of efficient non-noble bimetallic cocatalysts is also preferable, which could greatly reduce the cost of photocatalysts. In one of our recent reports, FeOOH loaded TiO 2 exhibited superior performance in photocatalytic herbicides mineralization . Thus, the combination of Fe and other low cost metal species such as Co and Cu as bimetallic cocatalysts to further enhance the efficiency of photocatalytic mineralization of herbicides is scarcely reported and is worthy to be thoroughly studied.…”

“…In one of our recent reports, FeOOH loaded TiO 2 exhibited superior performance in photocatalytic herbicides mineralization. 12 Thus, the combination of Fe and other low cost metal species such as Co and Cu as bimetallic cocatalysts to further enhance the efficiency of photocatalytic mineralization of herbicides is scarcely reported and is worthy to be thoroughly studied. Herein, novel nanoarchitecture comprising binary metal oxides/hydroxides as cocatalysts on PC50 (commercial benchmark anatase TiO 2 ), were synthesized using a reproducible surface impregnation method.…”

Facet Dependent Activity of Fe(III) Species Modified TiO2 for Simulated Sunlight Driven Fenton-like Reactions

“…However, the quantum efficiency of doped photocatalysts is usually reduced, because impurities can act as recombination centers for electron–hole pairs . Different from the high temperature required for Fe doped TiO 2 , − the TiO 2 surface modification with Fe (III) as a cocatalyst has an efficient and facile synthesis process. , Due to the low redox potential of Fe 3+ /Fe 2+ , Fe­(III) ions can effectively capture photogenerated electrons and boost the separation of electron hole pairs. Facet-dependent photocatalytic reactions on TiO 2 materials have also been widely studied .…”