Rapid Laser-Induced Highly Dispersed and Ultrafine N-Doped Graphene-Wrapped FeCo₂O₄ Nanoparticles for Nearly 100% Utilization and Conversion of Peroxymonosulfate into Singlet Oxygen

Abstract

Currently, catalysts with core–shell structures have an important role in catalytic performance and practical applications, but how to simplify the preparation method and a reasonable explanation of the activation mechanism are still lacking. In this work, we obtained highly dispersed and ultrafine laser-induced nitrogen-doped graphene-wrapped iron cobaltate (LI-FeCo2O4@NDG) catalysts by one-step carbonization of iron cobalt metal–organic framework (FeCo-MOF) precursors using a CO2 laser annealing technique under ambient conditions. An LI-FeCo2O4@NDG/peroxymonosulfate (PMS) system achieved a rapid degradation of sulfamethoxazole (SMX) with 92.2% degradation efficiency in 6 min. Meanwhile, LI-FeCo2O4@NDG exhibited low metal leaching (Co, 0.155 mg/L; Fe, 0.008 mg/L) and a high reaction rate constant (k = 0.413 min–1). Most importantly, the ability of the catalyst could achieve nearly 100% utilization and conversion of PMS to singlet oxygen (1O2). The activation mechanism may be explained that the electron pool and interfacial electric field formed by the LI-FeCo2O4@NDG with the core–shell structure could accelerate the electron supply and transfer to the PMS, facilitating the activation of PMS self-decomposition to produce more 1O2. Overall, this work is expected to open a new avenue for the construction of core–shell structures and a new insight for revealing its activation mechanism of PMS.

Do We Appropriately Detect and Understand Singlet Oxygen Possibly Generated in Advanced Oxidation Processes by Electron Paramagnetic Resonance Spectroscopy?

“…Moreover, the reactivity of 1 O 2 with many organic contaminants have actually been fairly established in aquatic photochemistry, , especially for (substituted) phenols and phenolates. , 1 O 2 has been proved to be not the major oxidant during the photodegradation of sulfamethoxazole (SMX) since the rate constant of SMX with 1 O 2 is far too low to result any meaningful decomposition within an acceptable timescale [ k (SMX+1O2) = 2.0 × 10 4 M –1 s –1 ] Nevertheless, many recent AOP studies claimed that 1 O 2 could efficiently degrade SMX or other organic contaminants [e.g., carbamazepine (CBZ)] − that have been reported to be recalcitrant to 1 O 2 attack . Moreover, 1 O 2 was even proposed to be able to mineralize organics (e.g., 4-chlorophenol) to CO 2 and H 2 O in a peroxymonosulfate-based AOP with 100% selectivity in generating 1 O 2 , but 1 O 2 is known to be too substrate-dependent to result in organic mineralization .…”

Current Mechanism of Peroxymonosulfate Activation by Cobalt-Based Heterogeneous Catalysts in Degrading Organic Compounds

“…Copyright 2022 Elsevier. (c) CDD diagrams of PMS adsorbed on N@C, FeCo 2 O 4 , FeCo 2 O 4 /N@C, and N@C/FeCo 2 O 4 /N@C. Adapted with permission from ref . Copyright 2023 American Chemical Society.…”

“…Spinel ferrite materials have demonstrated excellent properties and unique advantages in activating PMS, with CoFe 2 O 4 exhibiting the best activation and synergistic properties in most cases. ,, Several studies have investigated novel approaches to enhance the performance of CoFe 2 O 4 -based catalysts. For instance, Chen et al proposed a core–shell structure that effectively avoids ion leaching and improves catalytic stability. The sandwich structure model of N@C and FeCo 2 O 4 was used for the calculation, and the charge imbalance between FeCo 2 O 4 and N@C leads to the formation of the internal electric field and the configuration change of the FeCo 2 O 4 sandwich.…”

“…Among these reactions, the addition reaction on the orthocarbon atom of BPS was the most favorable. In recent years, ecological evaluation has become more widespread, and various software tools, such as ECOSAR ,,, and T.E.S.T., ,,, have been used to assess the toxic effects of OCs during the degradation process.…”

“…67 The arisen proportion of 1 O 2 on carbon-based surfaces is higher compared to metal surfaces due to the improved electron transport ability, and calculation work based on carbon surface has been reported more. 100,153,183 Wang et al 212 conducted detailed calculations on the reaction energy diagram involving singlet oxygen on catalysts doped with single atoms of the CoN 4 structure. In Figure 14a, it is observed that the steric hindrance of the coadsorption step on the g-C 3 N 4 structure is smaller compared to graphite doping, and the formation of 1 O 2 involves two coadsorbed PMS molecules.…”