Highly Efficient Heterogeneous Photo‐Fenton‐Like Catalyst of e‐Fe₂O₃/SiO₂/Attapulgite with Rich Oxygen Vacancies for Photocatalytic Degradation of Organic Pollutants

Abstract

Heterogeneous photo-Fenton oxidation is a promising solution to solve the problem of environmental pollution. Due to the low efficiency of the Fe 2 O 3 photo-Fenton catalyst, we loaded Fe 2 O 3 on the catalyst carrier of attapulgite (ATP) to obtain more active sites. Oxygen vacancies were introduced on the surface of the catalyst to improve the separation efficiency of photogenerated charges. The oxygen-vacancy-rich e-Fe 2 O 3 /SiO 2 /ATP Fenton-like photocatalyst was successfully synthesized by simple strategies. The oxygen vacancies were successfully introduced to the surface of the e-Fe 2 O 3 /SiO 2 /ATP catalyst by a solvothermal method, and verified by XPS, Raman and EPR spectra. The e-Fe 2 O 3 /SiO 2 /ATP Fenton-like photocatalyst shows excellent photocatalytic degradation activity of MB and RhB. 96 % of RhB was degraded by e-Fe 2 O 3 /SiO 2 /ATP with light in 60 min, and 95 % of MB was degraded by e-Fe 2 O 3 /SiO 2 /ATP with light in 60 min. Therefore introducing surface oxygen vacancies is an effective strategy to future improve the catalytic activity of photo-Fenton like catalysts.

Insights into the Formation Mechanism of Reactive Oxygen Species in the Interface Reaction of SO2 on Hematite

“…In contrast, there was scarce •OH radical signal for the α-Fe 2 O 3 sample vacuumed at a high temperature (573 K) owing to the removal of surface hydroxyl groups. Furthermore, the results of XPS (Table S1) and ESR (Figure S2) indicated that there was no discernible oxygen vacancy generation by the vacuuming and heat treatment in this experiment, 27,28 S3a), which is consistent with previous studies, which stated that the •OH radicals are primarily derived from H 2 O rather than O 2 . 29 In general, in the presence of water, •OH radicals can reconstitute to form H 2 O 2 in the aqueous phase through eq 1.…”

“…In contrast, there was scarce •OH radical signal for the α-Fe 2 O 3 sample vacuumed at a high temperature (573 K) owing to the removal of surface hydroxyl groups. Furthermore, the results of XPS (Table S1) and ESR (Figure S2) indicated that there was no discernible oxygen vacancy generation by the vacuuming and heat treatment in this experiment, , excluding the possible influence of surface oxygen vacancy on •OH radical generation. These results demonstrated the important role of surface hydroxyl groups in the formation of •OH radicals on fresh α-Fe 2 O 3 samples.…”

Modification of α-Fe2O3 Nanoparticles with Carbon Layer for Robust Photo-Fenton Catalytic Degradation of Methyl Orange

“…To provide a comprehensive discussion on the role of the conductive carbon layer, and H 2 O 2 in the photocatalytic degradation of methyl orange, we also consider the photo-Fenton-like process and its impact on the reaction mechanism [21][22][23][24][25]. When H 2 O 2 is added to the photocatalytic system, it can enhance the degradation of organic pollutants by generating additional hydroxyl radicals (•OH) via a photo-Fenton-like reaction using H 2 O 2 and Fe(II/III) redox in the presence of light.…”

“…The enhanced degradation can be attributed to the increased production of hydroxyl radicals through Fenton reaction involving H 2 O 2 and Fe ions. This suggests that both the photocatalytic process and the photo-Fenton-like process contribute synergistically to the degradation of methyl orange [21][22][23][24][25]. The concentration of H 2 O 2 and the initial pH of the solution were optimized to maximize the degradation efficiency.…”

“…Furthermore, the carbon layer increases the number of active sites on Fe 2 O 3 nanoparticles, and improves the electron mobility and effective charge carrier generation as compared to pure Fe 2 O 3 nanoparticles, leading to more efficient photocatalytic reactions [8,9]. Moreover, hydrogen peroxide (H 2 O 2 ) reagent can be added to the Fe 2 O 3 -based photocatalytic reaction to further increase the production of hydroxide free radicals (•OH) via the Fenton reaction [21][22][23][24], which enrich the organic compound oxidation process via the heterogeneous photo-Fenton-catalytic oxidation reaction [21][22][23][24]. These enhancements highlight the importance and novelty of using carbon-covered Fe 2 O 3 in Fenton photocatalytic degradation of organic compounds.…”