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Singlet oxygen (1O 2) is a highly effective reactive species in selectively oxidizing organic pollutants. However, it is still challenging to rationally design robust catalysts for the selective generation of 1O 2. Herein, the coordination and engineering architecture of the foam board-like CoSe 2 alloy were facilely constructed through a green solvent-free method and displayed almost 100% 1O 2 production selectivity. The CoSe 2 alloy showed excellent catalytic ability for the efficient and fast removal of organic pollutants via peroxymonosulfate (PMS) activation compared with previously reported cobalt-based catalysts. The CoSe 2 /PMS system exhibited strong resistance for a broad pH range (3.0–11.0) and various coexisting inorganic ions owing to the advantage of the strong bonding of Co-Se in CoSe 2 alloy. Mechanism studies revealed that 1O 2 was the only reactive oxygen species in the CoSe 2 /PMS system. Theoretical calculations demonstrated that Co was the dominant adsorption site for PMS in CoSe 2 , and the production pathway of 1O 2 was PMS* → *OH → *O → 1O 2. In addition, it was proved that *OH and *O served as the rate-determining steps for the formation of 1O 2 by PMS activation on CoSe 2 alloy. These findings provide a rational strategy for preparing a series of low-cost transition metal-based alloy catalysts for PMS activation to achieve high-efficiency 1O 2 production in the elimination of organic pollutants. [Display omitted] • The foam board-like CoSe 2 alloy was facilely fabricated through a green solvent-free method. • CoSe 2 exhibited excellent catalytic performance for PMS activation. • The CoSe 2 /PMS system achieved almost 100% 1O 2 production selectivity. • *OH and *O served as the rate-determining steps for the formation of 1O 2. • 100% sulfadiazine was stably removed via a continuous flow reactor in 6 h. [ABSTRACT FROM AUTHOR]

• Coral reef-like FeS 2 /C cs was prepared by a one-step solvothermal method. • FeS 2 in situ grew on the surface of waste corn stalks-derived carbon (FeS 2 /C cs). • FeS 2 /C cs exhibited a superior ability for activating PMS to degrade OTC. • SO 4 − and OH were identified as the major radicals for attacking OTC. • Toxicity of OTC could be effectively reduced via the FeS 2 /C cs + PMS system. Over the past few decades, organic pollution such as tetracyclines and dyes has caused harm to the environment, biology, and human health. Therefore, developing a green and efficient method for organic pollutant removal is urgent. Herein, a coral reef-like FeS 2 /C cs was successfully constructed by one-step solvothermal growth of FeS 2 on waste corn stalks-derived carbon. The as-prepared FeS 2 /C cs catalyst exhibited much better performance in activating peroxymonosulfate (PMS) for removing organic pollutants than the other candidates previously reported. Almost 100 % of oxytetracycline (OTC) could be degraded within 20 min. Various factors like PMS concentration, catalyst dosage, initial pH values, and temperature that influenced the degradation process were then investigated. Through quenching experiments and electron paramagnetic resonance (EPR), O 2 −, 1O 2 , SO 4 − and OH were determined to be involved in attacking OTC, in which SO 4 − play a major role and OH acted as the secondary role. Subsequently, degradation pathways of OTC were rationally proposed. Toxicity simulations demonstrated that the toxicity of OTC could be effectively reduced after degradation. Universal experiments showed that FeS 2 /C cs + PMS system could also effectively degrade other typical tetracyclines and dyes, such as tetracycline (TC, ∼100 %), chlortetracycline hydrochloride (CTC, ∼100 %), methylene blue (MB, ∼83 %) and rhodamine B (RhB, ∼95 %). Moreover, the FeS 2 /C cs could remain high catalytic activity in five cycles test. This study provides a green and efficient method for organic pollution removal and technical guidance for analyzing its environmental toxicology. [ABSTRACT FROM AUTHOR]

• Fine CoFe 2 O 4 was in-situ fabricated on biomass waste-derived porous carbon framework. • CoFe 2 O 4 /C exhibited large surface area of 733.1 m2/g and presented rich oxygen vacancies. • CoFe 2 O 4 /C catalysts can directly activate PMS to efficiently remove four typical quinolones. • ∼94.8% CIP, ∼96.8% OFL, ∼100% LEV, ∼86% NOR can be efficiently degraded in 12 min. • DFT calculations elucidated the possible adsorption behavior and activation mechanism. Rational design of the low-cost, highly efficient and easily recyclable catalyst to directly activate peroxymonosulfate (PMS) is crucial for the efficient removal of organic pollutants in the sewage treatment. Herein, hyperdispersed CoFe 2 O 4 spinel nanoparticles were successfully in-situ fabricated on biomass-derived 3D porous carbon framework (C) by the facile one-step solvothermal method (CoFe 2 O 4 /C). These as-prepared CoFe 2 O 4 /C exhibit superior performance in the Fenton-like removal of four quinolones by the combination of experimental work and theoretical calculation. Experimental results prove that CoFe 2 O 4 /C catalyst can directly activate PMS to efficiently remove four types of quinolones in 12 min without the external energy consumption. The characterization results show that hyperdispersed CoFe 2 O 4 (18.0 ± 5.0 nm) nanoparticles are uniformly anchored on the matrix of C, exhibit a large specific surface area of 733.1 m2/g, and present rich oxygen vacancies (O vs), thus exposing more reactive sites and generating more reactive oxygen species (ROS). In CoFe 2 O 4 /C + PMS system, ∼97.5% of ciprofloxacin (CIP) is removed within 12 min, which is far superior to other candidates previously reported. Other quinolones (e.g., ∼96.8% of ofloxacin (OFL), ∼100% of levofloxacin (LEV), and ∼86.4% of norfloxacin (NOR)) can also be efficiently degraded under the same conditions. Based on quenching experiments, electron spin resonance spectroscopy (ESR), and density functional theory (DFT) calculations, these superior activities are mainly due to the free radical (SO 4 ·-, ·OH, and ·O 2 –) and non-free radical (1O 2), whereas SO 4 ·- and ·OH are the major reactive oxygen species. In addition, these CoFe 2 O 4 /C catalysts remain stable even after five cycles. Subsequently, degradation pathways are rationally proposed. This work provides a feasible and universal strategy for the direct activation of PMS in wastewater treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rational design and synthetic strategies of multifarious SMOs are summarized. • Intrinsic relationship between SMO's structure and catalytic properties is analyzed. • The photocatalytic mechanism of SMOs for antibiotics degradation is revealed. • Challenges and prospects of SMOs for antibiotics degradation are highlighted. Due to the permanent harm to human health and ecosystem balance, antibiotic pollution in water has become an important direction of current environmental governance. Spherical metal oxides (SMOs) have been frequently utilized as effective heterogeneous photocatalysts for the efficient degradation of antibiotics due to their unique properties (e.g., strong light absorption ability, high separation efficiency of photo-generated electron-hole pairs, and good catalytic activity). This review will firstly focus on summarizing the rational design and synthesis of SMOs with various tuned microstructures such as hollow, porous shell, yolk shell, core shell, and nanoflowers. These structures can expose more active sites, achieve a higher utilization rate of light, enhance the mass transfer efficiency and improve the effective diffusion of reactive oxygen species (ROS). Secondly, this review will mainly analyze the intrinsic relationship between the structure of SMOs and their photocatalytic property, the ability to generate ROS, and the degradation pathway for antibiotics. Moreover, the photocatalytic mechanisms and recent progress of different SMO catalysts for degrading typical antibiotics are compared in detail. Finally, challenges and prospects of future direction in the development of SMOs for antibiotic degradation are reviewed. It is expected to provide a rational design of SMO catalysts for efficient photocatalytic degradation of environmental pollutants. [ABSTRACT FROM AUTHOR]

• The NCC (NiCo 2 O 4 grown on carbon) is developed as a robust photo-Fenton-like catalyst. • The synergistic effect between NC and carbon enhances the catalytic performance. • The NCC + PMS + L coupling system is universal for phenolic pollutants removal. • Degradation intermediates and removal mechanisms are identified and elucidated. Rational design of photocatalysts with the controllable structure to expose active sites is crucial to degrade phenolic pollutants. Herein, we report the in-situ synthesis of lily-like NiCo 2 O 4 nanosheets (0.95 nm) grown on waste biomass-derived carbon (abbreviated as NCC) for the highly efficient photocatalytic removal of phenolic pollutants through the integration of experiment and theory calculation. These as-fabricated NCC photocatalysts (2.29 nm) exhibit superior performance for the fast removal of phenolic pollutants (such as 4-Acetamidophenol (AP), phenol, and aspirin) in comparison with their counterpart and previously reported candidates. By using AP as a model molecule for mimicking pollutants, the photocatalytic degradation performance of NCC nanosheets is ∼ 1.3 and 1.9 times higher than that of pure NiCo 2 O 4 (NC) and porous carbon, respectively. Various factors that influenced the degradation process such as peroxymonosulfate (PMS) concentration, catalyst dosage, AP concentration, and initial pH are thoroughly investigated. The free radical quenching experiments and electron paramagnetic resonance (EPR) spectra further demonstrate the existence of SO 4 −·, ·OH, ·O 2 –, and 1O 2 in the reaction system and the ·O 2 – radical play a major role, which is also confirmed by the density functional theory (DFT) calculation. Several degradation pathways (e.g., demethylation, deacylation, hydroxylation, and ring-opening) are then proposed based on the detected intermediates. Finally, the high stability and good reusability of NCC nanosheets are confirmed via the degradation efficiency of over 85% even after five successive cycles. [ABSTRACT FROM AUTHOR]