Ag and Fe₃O₄ Comodified WO_3 – x Nanocomposites for Catalytic Photothermal Degradation of Pharmaceuticals and Personal Care Products

Abstract

Ag/Fe 3 O 4 /WO 3 − x nanocomposite photocatalysts, which consist of surface plasmon nanoparticle Ag, magnetically recoverable Fe 3 O 4 , and coral-like WO 3 − x , are constructed via two-step hydrothermal and photodeposition processes. The significantly strengthened photothermal catalytic-Fenton degradation performance under light irradiation is attributed to the formation of a hierarchical structure, as follows: (i) the unique 3D coral-like defective WO 3 − x nanorods possess the inherent properties of charge separation and can provide adequate surface active sites, while incident light is reflected multiple times within the nanorods to enhance light utilization; (ii) efficient photo-Fenton characteristics of Fe 3 O 4 nanomaterials with easy magnetic recovery and fast electron transfer emerging at the intimate interface of Fe 3 O 4 and WO 3 − x ; and (iii) the surface plasmon resonance (SPR) of Ag nanoparticles and photothermal effects. Radical scavenger experiments and electron spin resonance analysis indicated that •OH and •O 2 − are the main active species for the removal of broad-spectrum pharmaceuticals and personal care products. Furthermore, a possible photothermal catalytic-Fenton synergistic mechanism is proposed. This study will present novel deep insights into the design of photothermal catalytic-Fenton degradation systems using magnetically Fe 3 O 4 coupled WO 3 − x semiconductors and the SPR effect.

Fe3O4 Nanoparticles Synthesized from Waste Iron Dust for Sunlight-Boosted Photodegradation of Nitrophenols and Their Mixtures

“…It can also be analyzed from Figure b that the integrated area of Fe­(II) is higher than that of Fe­(III) as compared to its parent form, which indicates the abundance of a large number of Fe­(II) phases (active form required for photo-Fenton-type reactions) as compared to the Fe­(III) phase . Further, deconvolution of O 1s short scan spectra shows mainly three peaks at ∼530.0, ∼531.2, and ∼532.4 eV, which correspond to Fe–O, surface adsorbed oxygen present in the form of CO 2 , and water adsorbed (Figure c) …”

“…Further, the analysis of surface bindings corresponding to respective elements was performed by deconvoluting the short scan spectra of two elements, i.e., F 2p and O 1s . It was found that on deconvolution of Fe 2p , six peaks are observed at ∼711.0, ∼713.0, ∼719.3, ∼724.4, ∼726.4, and ∼728.8 eV for Fe 2p 3/2 (II), Fe 2p 3/2 (III), Fe 2p 3/2 (satellite), Fe 2p 1/2 (II), Fe 2p 1/2 (III), and Fe 2p 1/2 (satellite), respectively (Figure b) . It can also be analyzed from Figure b that the integrated area of Fe­(II) is higher than that of Fe­(III) as compared to its parent form, which indicates the abundance of a large number of Fe­(II) phases (active form required for photo-Fenton-type reactions) as compared to the Fe­(III) phase .…”

“…However, after chemical reduction, the reduced version showed different diffracted peaks at 2θ values of ∼30.6, ∼35.7, ∼43.4, ∼53.8, ∼57.5, ∼62.9, ∼71.6, ∼74.2, and ∼87.3, which correspond to (220), (311), (400), (422), (511), (440), (620), (533), and (642), respectively, obtained by comparing the pattern with the pure phase of Fe 3 O 4 having JCPDS No. 03-0863 as shown in Figure c (black lines). , The crystals diffracted from chemically reduced iron oxide were thus identified as inverse spinels of Fe 3 O 4 (FeO.Fe 2 O 3 ) without any other metallic impurity.…”

“…52 Further, deconvolution of O 1s short scan spectra shows mainly three peaks at ∼530.0, ∼531.2, and ∼532.4 eV, which correspond to Fe−O, surface adsorbed oxygen present in the form of CO 2 , and water adsorbed (Figure 2c). 51 The morphological changes before and after the chemical reductions were also analyzed by SEM analysis. It was found that IOD showed a spherical-like geometry in low-resolution SEM image (Figure S1a, see the Supporting Information), and the high-resolution SEM image showed spherical particles (indicated by yellow highlighted circles in Figure S1b (see the Supporting Information)), with an average size of ∼(110 ± 10) nm.…”

“…03-0863 as shown in Figure 1c (black lines). 12,51 The crystals diffracted from chemically reduced iron oxide were thus identified as inverse spinels of Fe 3 O 4 (FeO.Fe 2 O 3 ) without any other metallic impurity.…”