Insight into the Enhanced Photo-Fenton Degradation Performance of Fe₃O₄@β-Ketoenamine-Linked Covalent Organic Framework

Abstract

The sluggish charge-transfer kinetics of Fe(II) regeneration, unsatisfactory utilization of H 2 O 2 , and low reaction efficiency remain largely unresolved in Fe 3 O 4 -based heterogeneous photo-Fenton systems. Herein, an in situ covalent attaching strategy was employed to fabricate Fe 3 O 4 @covalent organic framework (COF) core−shell heterostructures. By virtue of this, enhanced photoresponsive behavior was obtained to tailor the regeneration kinetics for Fe(II) and ideal catalytic sites for H 2 O 2 were provided. Molecular engineering was further employed to manipulate the linkages (β-ketoenamine or imine) of the COFs. Bearing a β-ketoenamine linkage, the Fe 3 O 4 @ TpTta COF exhibited remarkably fast kinetics (0.111 min −1 ) as well as exceptional pH tolerance in photo-Fenton degradation of methylene blue, which stands out among the state-of-the-art photocatalysts. Combined with theoretical calculations, the electron-transfer route and interfacial interactions between the oxidant and catalysts with different linkages were fully revealed, giving insight into the synergistic relationship between photocatalysis and Fenton reactions.

Covalent–Organic Framework (COF)‐Core–Shell Composites: Classification, Synthesis, Properties, and Applications

“…Reproduced with permission. [ 189 ] Copyright 2023, American Chemical Society. Reproduced with permission.…”

“…This section provides a systematic discussion of these classical synthetic methods. In particular, Table 2 summarizes the morphology of some core-shell hybrids as well as the synthesis conditions to COF@MoS 2 Seed-mediated in situ growth 120 °C for 72 h [185] dye/MOFs@COFs Seed-mediated in situ growth Room temperature for 3 d [186] aza-MOF@COF Seed-mediated in situ growth 110 °C for 3 h [187] ZW-COF@CNT One-pot polymerization 120 °C for 72 h [188] COF@CNT One-pot polymerization 120 °C for 72 h [148] Fe 3 O 4 @TpTta One-pot polymerization 120 °C for 72 h [189] CuO@TAPB-DMTP-COF One-Pot polymerization 120 °C for 72 h [190] (Continued) Reproduced with permission. [ 185] Copyright 2022, Elsevier Ltd. Reproduced with permission.…”

Photoactive Fe3O4@Fe2O3 Synthesized from Industrial Iron Oxide Dust for Fenton-Free Degradation of Multiple Organic Dyes

“…4−9 During the AOP, the complex organic frameworks of organic pollutants are broken into small molecular weight hydrocarbons, carbon dioxide, and water, 10 while in the case of inorganic contaminants they are reduced from higher toxic oxidation states to lower nontoxic oxidation states. 11 From the many active iron-based catalysts as their (oxy) hydroxides, such as hematite, 4 magnetite, 12 ferrihydrite, 13 etc., magnetite (Fe 3 O 4 ) and magnetite-based heterogeneous materials have been preferred for the photodegradation applications because of their easier separations after the experiments from the reaction mixture, 14 such as Fe 3 O 4 @void@CdS, 15 Fe 3 O 4 @rGO@TiO 2 , 16 Fe 3 O 4 @Polydopamine-Ag Core−Shell, 17 and Fe 3 O 4 @β-ketoenamine 18 used for the degradation of methylene blue (MB) dye, Fe 3 O 4 /α-FeOOH Nanocomposites for removal of tetracycline hydrochloride, 19 Fe 3 O 4 /CeO 2 for degradation of 4-chlorophenol, 20 and Fe 3 O 4 @EDTA-Ag for degradation of organic dyes including rhodamin B (Rh−B), MB, alizarin yellow (AY), neutral red (NR), orange II/acid orange-7 (Orng-II), and azophloxine (Azp) in aqueous solution. 21 Concerning water contaminants, industrial effluents are released from carpet, paper, textile, distillery, leather, and printing in large amounts and contains a lot of toxic organic dyes.…”

“…Iron-based materials/nanomaterials showed a wide range of applications, especially their catalytic activities in various organic and inorganic reactions. − Additionally, showed their potential to acquire usable water from the contaminated wastewater using the process of advanced oxidation processes (AOP) including light-induced AOP. − During the AOP, the complex organic frameworks of organic pollutants are broken into small molecular weight hydrocarbons, carbon dioxide, and water, while in the case of inorganic contaminants they are reduced from higher toxic oxidation states to lower nontoxic oxidation states . From the many active iron-based catalysts as their (oxy) hydroxides, such as hematite, magnetite, ferrihydrite, etc., magnetite (Fe 3 O 4 ) and magnetite-based heterogeneous materials have been preferred for the photodegradation applications because of their easier separations after the experiments from the reaction mixture, such as Fe 3 O 4 @void@CdS, Fe 3 O 4 @rGO@TiO 2 , Fe 3 O 4 @Polydopamine-Ag Core–Shell, and Fe 3 O 4 @β-ketoenamine used for the degradation of methylene blue (MB) dye, Fe 3 O 4 /α-FeOOH Nanocomposites for removal of tetracycline hydrochloride, Fe 3 O 4 /CeO 2 for degradation of 4-chlorophenol, and Fe 3 O 4 @EDTA-Ag for degradation of organic dyes including rhodamin B (Rh–B), MB, alizarin yellow (AY), neutral red (NR), orange II/acid orange-7 (Orng-II), and azophloxine (Azp) in aqueous solution …”

Brown TiO2-Based Fe–Ni Thiospinel Binary Nanocomposite as a Sustainable Catalyst with Synergistic Improvement Assisted by H2O2 and Ascorbic Acid for Round-the-Clock Removal of Rhodamine B

“…Advanced oxidation processes (AOPs) are applied technologies used to efficiently treat wastewater by generating reactive oxygen species (ROS) . Depending on the production route of ROS involved in organic pollutants, AOPs are classified into ozonation, photocatalysis, , Fenton/Fenton-like catalysis, − photo-Fenton/photo-Fenton-like, − phyto-Fenton, electrochemical oxidation, sulfate radical-based AOPs, etc. As a promising AOP, the Fenton process describes a simple method for the formation of OH radicals from the decomposition of hydrogen peroxide using iron ions (Fe 2+ /Fe 3+ ) as catalysts in an acidic aqueous solution at room temperature .…”