Plasmon-Assisted Degradation of Toxic Pollutants with Ag−AgBr/Al₂O₃ under Visible-Light Irradiation

Abstract

AgBr coated with silver (Ag) nanoparticles (NPs) were highly dispersed on ordered mesoporous γ-Al 2 O 3 (MA) by the deposition-precipitation method with surfactant (Ag-AgBr/MAP). The catalyst showed high and stable photocatalytic activity for the degradation and mineralization of toxic persistent organic pollutants, as demonstrated with 2-chlorophenol (2-CP), 2,4-dichlorophenol, and trichlorophenol under visible light or simulated solar light irradiation. The dispersion of Ag-AgBr NPs on MA strongly affected their photoactivity. On the basis of electron spin resonance and cyclic voltammetry analyses under a variety of experimental conditions, two plasmon-induced electron-transfer processes were verified from the excited Ag NPs to AgBr and from 2-CP to the Ag NPs, resulting in O 2• •-radicals were primary active species, whereas the excited h + on Ag NPs was involved in the photoreaction system of Ag-AgBr/MAP. The highly efficient degradation of pollutants came from both photoexcited AgBr and plasmon-excited Ag NPs. Accordingly, the plasmoninduced electron-transfer processes elucidated the photostability of Ag-AgBr/MAP. These findings indicate potential applications of noble metal NPs in the fields of developing visible-light-sensitive photocatalysts and photovoltaic fuel cells.

Mechanism and experimental study on the photocatalytic performance of Ag/AgCl @ chiral TiO2 nanofibers photocatalyst: The impact of wastewater components

“…In consequence, it can be concluded that HO· plays a key role in the photocatalytic degradation of EE2. This result is consistent with above mentioned photocatalytic mechanism of Ag/AgCl @ chiral TiO 2 nanofibers since all of h + and Cl 0 can undergo a series of reactions and produce HO· [23,24]:…”

Characterization and photostability of Cu2O–Ag–AgBr/Al2O3 for the degradation of toxic pollutants with visible-light irradiation

“…Cu 2 O nanocubes were prepared as described previously, and stored in refrigerator before used [29]. Then, Cu 2 O was deposited onto Al 2 O 3 during the deposition-precipitation process of Ag-AgBr as reported in our previous work [27]. Briefly, 0.08 g of Cu 2 O and 0.6 g of ␥-Al 2 O 3 was added to 60 mL of distilled water, and the suspension was sonicated for 30 min.…”

“…Therefore, the formation of bigger Ag 0 cluster leaded to the decrease of the photocatalyst activity because the surface plasmon resonance of Ag NPs depended on particle size [32][33][34]. In contrast, Ag-AgBr/Al 2 O 3 exhibited activity successive cycles without any treatment [27], indicating no formation of the bigger Ag 0 cluster in the process of photocatalysis. The results verified that the faster transfer of electron occurred between Ag + and Ag 0 on the surface of In order to illustrate the effect of Cu 2 O on the charge separation and charge-transfer processes, CV analyses were performed at the different photoanodes in a N 2 -saturated 0.1 M sodium sulfate aqueous solution under > 420 nm visible light irradiation (Fig.…”

“…Cu 2 O with a CB level of −1.4 eV-SHE, is known to be one of the oxides with high level of conduction bands [24]. Therefore, the photogenerated electrons in Cu 2 O can easily transfer to other semiconductor [25] pollutants, due to the Ag NPs plasmon-assisted effect on the AgBr photocatalyst [27]. However, the electron injection from Ag NPs to AgBr, resulted in the oxidation of some Ag NPs to Ag + , which were dissolved in water and resulting in secondary water pollution [18].…”

Visible-light photocatalytic activity and mechanism of novel AgBr/BiOBr prepared by deposition-precipitation

“…AgBr is an important semiconductor widely used as a photosensitive material in photography and as a photocatalyst for the degradation of pollutants or destruction of bacteria [24,[30][31][32][33][34][35][36][37][38][39][40][41][42][43][44]. Compared with BiOBr [18], AgBr [45] has a narrower band gap and higher visible-light absorption.…”