MOF-Derived Porous Fe2O3 Nanoparticles Coupled with CdS Quantum Dots for Degradation of Bisphenol A under Visible Light Irradiation

Abstract

In this work, CdS quantum dots (QDs) were planted on magnetically recyclable porous Fe2O3 (denoted as F450) to obtain CdS QDs/porous Fe2O3 hybrids (denoted as X–CdS/F450, in which X is the immersion times of CdS QDs). Porous Fe2O3 was first obtained by pyrolysis from an iron-containing metal–organic framework by a two-step calcination method. Next, CdS QDs (of average size 3.0 nm) were uniformly and closely attached to the porous F450 via a sequential chemical-bath deposition strategy. As expected, the X–CdS/F450 hybrids serve as high-performance photocatalysts for the degradation of bisphenol A, a typical endocrine-disrupting chemical. Almost ∼100% of the bisphenol A was degraded over 5-CdS/F450 after visible light irradiation for 30 min (λ ≥ 420 nm). In comparison, the degradation efficiency of pure F450 powder is 59.2%. The high performance of 5-CdS/F450 may be ascribable to the fast electron transport of porous F450, the intense visible-light absorption of the CdS QDs and the matched energy levels between CdS and F450. More significantly, through the photocatalytic degradation reaction, the X–CdS/F450 hybrids can easily be recovered magnetically and reused in subsequent cycles, indicating their stability and recyclability.

Strategy for Encapsulation of CdS Quantum Dots into Zeolitic Imidazole Frameworks for Photocatalytic Activity

“…ZIF-8 crystals were synthesized according to previous reports [ 16 , 17 , 18 , 19 , 20 ]. For ZIF-8, first, 0.9 g (3.0 mmol) of Zn(NO 3 ) 2 ∙6H 2 O was dissolved in 30 mL of MeOH.…”

“…This tendency obstructs the utilization of QDs in photocatalytic applications [ 6 , 7 , 8 ]. To address this issue, several studies have explored the concept of the encapsulation of QDs into high porous scaffolds such as mesoporous materials [ 9 , 10 ], zeolites [ 11 , 12 ], polyoxometalate [ 13 , 14 ], and metal organic frameworks (MOFs) [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. Recently, zeolitic imidazole frameworks (ZIFs), which are a class of MOFs, have been considered as an attractive class of porous scaffold materials for the incorporation of various components into the ZIF-8 network, owing to their high tunability and chemical and moisture stability compared to other MOFs [ 26 , 27 , 28 ].…”

“…Lu et al reported an exquisite approach in which a variety of QDs were encapsulated into ZIF-8 by employing polyvinylpyrrolidone (PVP) as the surfactant for surface modification of the QDs [ 15 ]. Several studies have reported this strategy of encapsulating QDs, including PVP-covered QDs such as CdS, CdTe, and CdSe, or nanoparticles, into ZIF-8 growth to be very effective [ 16 , 17 , 18 , 19 , 20 ]. In particular, the widely used method employing PVP as the binder between QDs and ZIF-8 is limited to complete removal of PVP after growth.…”

Assembling Ultrafine SnO2 Nanoparticles on MIL-101(Cr) Octahedrons for Efficient Fuel Photocatalytic Denitrification

“…The absorption band of MIL-101(Cr) in the UV region was assigned to π-π* transitions of the ligands and Cr (III)-oxide clusters, whereas the visible-light absorption came from Cr 3+ -oxide clusters, which characteristically absorbed at 450 and 600 nm (as also reported in the literature [17,34,37]). In the spectra of the SnO 2 @MCr samples, the absorption edge of SnO 2 was undisturbed after the SnO 2 QDs was grown on the on MIL-101(Cr), possibly because the SnO 2 QDs could not alter the crystal lattice of MIL-101(Cr) [38]. The Mott-Schottky plots analyzed at 500 and 1000 Hz are displayed in panels (b) and (c) of Figure 7, respectively.…”

Nanohollow Titanium Oxide Structures on Ti/FTO Glass Formed by Step-Bias Anodic Oxidation for Photoelectrochemical Enhancement

“…In electrochemical devices, oxidation and reduction occur on the surfaces of photosensitive electrodes with the help of extra photoinduced charged carriers, which can be used to enhance chemical reactions and sensing performance. Therefore, the most common materials, including titanium oxide (TiO 2 ) [ 12 , 13 ], ferric oxide (Fe 2 O 3 ) [ 14 , 15 ] and zinc oxide (ZnO) [ 16 , 17 ], have been investigated widely for decades due to their natural abundance, high chemical stabilities, low costs and low toxicities, especially for realizing superior performance by means of various nanostructures [ 18 ]. TiO 2 is the most promising material due to its various fabrication techniques and biocompatibility [ 19 ].…”