Herein, a novel CeO2-supported CuO composite (denoted as CuO/CeO2) is rationally designed and synthesized via a facile strategy for peroxymonosulfate (PMS) activation to degrade fluorinated antibiotic (namely florfenicol). Benefiting from the synergistic effects between CeO2 and CuO, abundant Ce3+/Ce4+ and Cu+/Cu2+ redox couples and oxygen vacancies are formed in the composite, which can significantly accelerate interfacial charge transfer and provide sufficient active sites. The optimized CuO/CeO2 catalyst shows exceptional catalytic performance, achieving 95.9% removal efficiency of florfenicol within 16 min, together with excellent pH adaptability, anti-interference capacity, and reusability. The mechanistic analysis reveals that PMS is firstly adsorbed on the CuO/CeO2 surface to form CuO/CeO2-PMS* complexes, which then undergoes disproportionation to produce 1O2. Meanwhile, O2•– can also transform PMS into SO5•‒, which further decomposes into 1O2. The nonradical pathway dominated by 1O2 is responsible for the degradation of florfenicol, whereas radical species and high-valent copper contribute minimally. All in all, this work provides a high-efficiency strategy for selective 1O2 generation in advanced oxidation processes, offering a promising approach for fluorinated antibiotic wastewater remediation.

Developing novel technology for treating wastewater containing fluorinated antibiotic will exercise a meaningful influence on ecological environment. In this study, low-coordinated cobalt nanoparticle is embedded into carbon nitrogen polymer to construct the Schottky heterojunction (namely Co/g-C3N4), then activating peroxymonosulfate (PMS) for the degradation of ofloxacin. Notably, the formation of Schottky heterojunction causes the charge redistribution at the interface, so offering more active sites and accelerating the charge transfer. More importantly, the mechanism of peroxymonosulfate activation is transformed into nonradical pathway from radical pathway after the combination of cobalt nanoparticle with carbon nitrogen polymer. Briefly, PMS is first adsorbed onto Co/g-C3N4 to form Co/g-C3N4-PMS* complex, and then most Co/g-C3N4-PMS* complex is decomposed into 1O2, which plays a major role in ofloxacin degradation. There is hydrogen radical (H center dot) generated during the process of PMS activation over Co/g-C3N4, and H center dot can break C-F bonds, thereby achieving satisfactory defluorination rate. Furthermore, degradation pathways of ofloxacin and toxicity of degradation byproducts are also clarified in detailed. In conclusion, current work can provide a valuable reference for future research on the treatment of wastewater containing fluorinated antibiotics.

The development of a facile detection method for per- and polyfluoroalkyl substances (PFAS) is of great significance to environmental protection and public health security. Herein, we successfully fabricated an iron-based nanozyme (denoted as P-ZVI/Fe2O3@C) with core-shell structure via a feasible route. The built-in electric field (BEF) reduced interfacial resistance, accelerated charge transfer and exposed more active sites. The doped phosphorus formed coordination interactions with iron sites and modulated their electronic structure, which induced an upward shift of the d-band center. Benefiting from the above advantages, P-ZVI/Fe2O3@C exhibited excellent oxidase-like, peroxidase-like and laccase-like activities. More importantly, P-ZVI/Fe2O3@C possessed an ultrahigh affinity toward PFAS, enabling rapid adsorption and subsequent decomposition of PFAS molecules. Taking advantage the oxidase-like and laccase-like activities of P-ZVI/Fe2O3@C, we established two colorimetric assays for the detection of five types of PFAS. These methods featured a wide linear range and a low limit of detection. On the basis of enzyme-like activity and reaction time points, we further constructed a four-channel sensing array. Combined with machine learning algorithms, this array achieved accurate discrimination and quantitative detection of various PFAS. In conclusion, this study proposed a feasible strategy for rapid and sensitive detection of PFAS, which provided a reference for the precise analysis of multiple PFAS in real water environments.

Developing novel technique for effective degradation of fluorinated antibiotic is of great significance. Herein, we adopt a simple ship-in-a-bottle strategy to prepare Co(OH)2/C composite with hollow structure. Notably, spatial confinement effect triggered by carbon sphere can promote the mass transfer process between PMS and Co (OH)2/C, so Co(OH)2/C displays high efficiency of PMS activation. As guessed, the Co(OH)2/C-mediated PMS system can realize effective degradation of ofloxacin in a short time, and observed rate constant is as high as 1.32 min-1. Because of large layer spacing and amphoteric attribute of Co(OH)2, interestingly, the Co(OH)2/C-mediated PMS system also exhibits superb anti-interference ability for inorganic ions and acid fluctuation. More importantly, in-situ characterization analyses reveal that the formation of Co(OH)2/C-PMS* complex is the first step during the process of PMS over Co(OH)2/C, and the Co(OH)2/C-PMS* complex is then decomposed into equivalent to Co4+ = O and H center dot, thereby achieving high removal efficiency of total organic carbon and satisfactory defluorination rate. In addition, pathways of ofloxacin degradation and toxicity of degradation intermediates are investigated in detailed. To sum up, current work offers a promising technique for effective treatment of wastewater containing fluorinated antibiotic.

Direct in-situ electrosynthesis of hydrogen peroxide (H2O2) by a two-electron oxygen reduction (2e-ORR) is an efficient and environmentally friendly method. However, the yield and selectivity of 2e-ORR are limited by slow oxygen transfer and competitive four-electron oxygen reduction (4e-ORR). Engineering hydrophobic interface is a vital modification method to fast capture and transfer oxygen. Herein, we designed a pyrrole-rich nitrogen-doped hollow porous carbon spheres containing oxygen-containing functional groups and hydrophobic interfaces (CSN-X), which provided lots of gas-liquid-solid triple-phase interfaces for enhancing yield and selectivity of 2e-ORR. In 1.0 M Na2SO4, CSN-750 exhibited excellent activity for H2O2 production with 95% H2O2 selectivity at 100 mA cm-2. Due to the super hydrophobicity, H2O2 could be effectively released during the production. Thus, CSN-750 exhibited a remarkable H2O2 yield rate of 75 mmol L-1 h-1 in a two-compartment device. On the basis of defective carbon sphere structure and hydrophobic interface, our work provided a perspective to reveal the mechanism of electrocatalytic H2O2 production.

Effective fracture of the C-F bond is the key prerequisite for achieving advanced degradation of fluorinated antibiotics. Herein, a newly designed Co9S8/CQDs/ZnIn2S4 heterojunction with a strong internal electric field is synthesized and employed for photocatalytic ofloxacin degradation. Interestingly, introduced carbon quantum dots (CQDs) act as efficient charge transfer mediators to overcome the interface barrier of the heterojunction, thereby magnifying the internal electric field effect with an intensity enhancement of approximately 2.8-fold. More importantly, the enhanced hydrophilicity endows the Co9S8/CQDs/ZnIn2S4 heterojunction with presentable H2O adsorption capacity, and adsorbed H2O is then dissociated into OH- and H+. Notably, photogenerated electrons can couple with H+ to trigger the fracture of the C-F bond, while photoinduced holes can activate OH- to generate OH• for realizing advanced mineralization of ofloxacin. Briefly, the Co9S8/CQDs/ZnIn2S4 heterojunction can directly activate water to achieve the degradation of ofloxacin under visible light irradiation. Furthermore, the intermediates generated during ofloxacin degradation and their toxicity are investigated in detail. Collectively, the current results can provide an important reference for further research on photocatalytic wastewater treatment.

Herein, for the first time, MOF-on-MOF-derived CuO/Co3O4 composites with core-shell structure is prepared. The internal electric field formed at the heterojunction interface can accelerate charge transfer and offer more active sites, so enhancing the performance of CuO/Co3O4 composites in formaldehyde degradation via peroxymonosulfate (PMS) activation. It is surprised to find that the adjustment of core and shell position in CuO/Co3O4 composites has an important impact on the mechanism of PMS activation. Under the mediation of internal electric field, free electron will gather around Co3O4 component of CuO/Co3O4 composites. When Co3O4 is served as the shell of CuO/Co3O4 composite (marked as CuO/Co3O4-1), CuO/Co3O4 composite will become electron donor and provide electron to activate PMS for producing SO4 center dot- and OH center dot, which can oxidize formaldehyde into CO2 and H2O. Interestingly, CuO/Co3O4 composite will become electron acceptor when CuO is employed as the shell (denoted as CuO/Co3O4-2), so PMS can be easily oxidized into SO5 center dot- and then decomposed into 1O2. Due to the feature of 1O2 being moderate oxidation ability, formaldehyde can be selectively converted by 1O2 into formic acid with high economic value. Additionally, theoretical calculation based on density functional theory further proves these results. This work clarifies the effects of core and shell exchanges in CuO/ Co3O4 composite on catalytic activity, sharing some new insights for selective degradation of formaldehyde.

In this work, ZIF-67/Fe nanozymes with specific binding sites toward tetracycline antibiotics (TCs) were synthesized via a one-step method, taking advantage of the strong interaction between Fe and oxygen-containing functional groups in TCs. Taking advantage of the specific enhancement effect of TCs on the peroxidase-like activity of ZIF-67/Fe, a high-performance colorimetric sensor array was constructed. This array could successfully discriminate four types of TCs, namely oxytetracycline, tetracycline, doxycycline, and doxycycline hydrochloride. It exhibited a linear detection range of 50-1000 mu g L-1 for all four antibiotics, with limits of detection (LOD) as low as 17.78, 19.71, 33.39, and 38.05 mu g L-1, respectively. Density functional theory (DFT) calculations revealed that Fe doping significantly enhanced the peroxidase-like activity of the nanozyme by facilitating electron transfer between the nanozyme and TCs. Furthermore, the ZIF-67/Fe nanozyme could effectively achieve TC removal after the detection process, and it still maintained the capability to accurately distinguish tetracycline antibiotics in real water samples. The one-step preparation strategy proposed in this study simplifies the synthesis process of MOF-based nanozymes. The constructed sensor array breaks through the technical bottleneck that traditional methods find it difficult to distinguish antibiotics of the same category. With the dual functions of high-sensitivity detection and pollutant removal, it provides a new idea for the accurate monitoring and control of TCs in aquatic environments.

In this study, bimetallic phosphide (FeP-CoP3) was synthesized via a MOF-on-MOF strategy, using FeCo Prussian blue analogues (FeCo-PBA) as the precursor and zeolitic imidazolate framework-67 (ZIF-67) as the protective shell. Characterization via TEM, XRD and FTIR revealed that the loading of ZIF-67 induced the formation of heterojunctions between FeP and CoP3, thereby achieving more thorough phosphidation of FeCo-PBA. FeP-CoP3 showed enhanced peroxidase (POD)-like activity with a specific activity of 51.08 U mg-1, 3.3 times that of FeCo-PBA-P (direct phosphidation of FeCo-PBA). Utilizing the inhibitory effect of tannic acid (TA) on the POD-like activity of FeP-CoP3, a colorimetric detection system was further constructed, exhibiting a linear range (LR) of 0.1 - 6.0 μM and a limit of detection (LOD) of 0.029 μM for TA detection. A smartphone-mediated portable trichrome (red-green-blue) sensor with a LOD of 0.05 μM of TA was developed. The colorimetric sensor exhibits a detection recovery rate of 94.2 to 109.2% for TA in actual beverages, demonstrating its potential for application in the beverage field. Density functional theory (DFT) calculations verified that FeP-CoP3 enables easier H2O2 adsorption and ·OH generation, resulting in enhanced POD-like activity. This work provides a practical method for designing new POD-like nanozymes and rapid TA detection.

It is of great significance to develop effective process for advanced degradation of fluorinated antibiotics. Herein, phosphorus-doped Co3O4 (P-Co3O4) as peroxymonosulfate (PMS) activator is synthesized. Introduced phosphorus can react with cobalt site of Co3O4 to trigger the d-p orbital hybridization, thereby promoting the oxygen vacancy formation and regulating the d-band center of Co3O4. Importantly, the existence of oxygen vacancy boosts the binding of Co site with terminal oxygen of PMS, and the d-p orbital hybridization effect enhances the electron delocalization of d-orbital. Thus, PMS adsorbed on P-Co3O4 can be easily activated to generate highvalent metal-oxo species (Co4+ = O), which plays an important role in florfenicol degradation. More interestingly, introduced phosphorus can serve as Br & oslash;nsted base site to capture H+ during the process of PMS, thereby facilitating the formation of active hydrogen that breaks the C-F bond of florfenicol. As a result, the P-Co3O4-mediated PMS system shows satisfactory removal efficiencies of total organic carbon and F ion. Furthermore, florfenicol degradation pathways are investigated, and its by-products are proven to be low toxicity or nontoxic. In short, current work not only elucidates positive role of d-p orbital hybridization, but also provides a promising technique for effective treatment of wastewater containing fluorinated antibiotics.

Glyphosate residues in aquatic ecosystems pose serious threats to ecological safety and public health owing to their strong biological recalcitrance and intrinsic toxic properties. Herein, sulfur-doped Fe2O3 (designated S-Fe2O3) is synthesized via a facile sulfur annealing strategy to tune the electronic configuration of Fe sites and enhance its catalytic activity toward peroxymonosulfate (PMS) activation. Comprehensive characterizations confirm the successful formation of Fe-S bonds, abundant oxygen vacancies, and an increased fraction of surface Fe2+ after sulfur modification. More importantly, sulfur incorporation regulates the spin state of Fe active sites and lowers the work function of Fe2O3, which accelerates interfacial charge transfer. In addition, the generated Fe-S bonds shift the Fe d-band center upward, further elevating the PMS activation capability of S-Fe2O3. Benefiting from the optimized electronic structure, the S-Fe2O3/PMS system realizes 94.6% glyphosate elimination within 14 min, with its reaction rate constant 7.8 times larger than that of bare Fe2O3. Meanwhile, S-Fe2O3 exhibits excellent pH adaptability and prominent anti-interference performance against coexisting inorganic anions. Radical trapping and EPR tests further validate that 1O2 serves as the dominant reactive species driving glyphosate degradation, while both SO4•‐ and •OH also contribute to pollutant removal. Collectively, this work offers a facile modification route for iron-based catalysts and provides a promising strategy for remediating glyphosate-contaminated wastewater.

To address the limitations of poor dispersion, slow charge transfer, and insufficient stability of Co-based catalysts in peroxymonosulfate (PMS) activation for antibiotic degradation, we innovatively modified Co3O4 surface with phosphate group. Subsequently, the catalytic performance of the modified catalyst (denoted as P-Co3O4-2) for PMS activation for sulfamethoxazole degradation was systematically explored. Interestingly, the phosphate group modification can significantly enrich surface hydroxyl groups and oxygen vacancies on Co3O4. The increased hydroxyl groups can promote the hydrophilicity and aqueous dispersion of P-Co3O4-2, while the enhanced oxygen vacancies can accelerate metal valence cycle and interfacial charge transfer. As a result, the P-Co3O4-2 can effectively activate PMS to generate free radicals (SO4•- and •OH) and high-valent metal-oxo species (Co4+=O). In the P-Co3O4-2/PMS system, the highest removal efficiency of sulfamethoxazole was as high as 96.4% within 16 min, and possible pathway of sulfamethoxazole degradation was also studied. Additionally, surface-bound phosphate group acted as a protective layer, suppressing Co leaching and improving catalytic stability. In short, this work provided a novel and effective surface modification strategy for cobalt-based catalysts, offering a promising approach for the remediation of antibiotic-contaminated wastewater.

This work clarifies the role of spin-orbit coupling in catalyst performance, offering a promising technology for advanced degradation of fluorinated antibiotics. Firstly, we adopt sulfur doping strategy to prepare Co3O4/CoS composite as the activator of peroxymonosulfate (PMS). The construction of amorphous structure offers more active sites. Notably, d-p orbital hybridization effect between sulfur and cobalt can induce the generation of more unpaired electrons and the rise of d-band center, which drives the transformation of Co sites from low to high spin states. These changes can accelerate charge transfer and enhance adsorption capacity for PMS. Formed Co3O4/CoS-PMS* composite can easily dissociate out H+ and combine with unpaired electrons to produce H center dot, thereby realizing satisfactory defluorination efficiency. Meanwhile, the Co3O4/CoS-PMS* composite losing H+ is converted into high-valent metal complexes by the fracture of peroxy bond, further realizing advanced mineralization of florfenicol. These results provide the valuable reference for future research.

Fluoride (F-) is widely distributed in nature, but its excessive discharge into the environment can lead to severe ecological and health problems. Therefore, it is of very great significance to develop sensitive and accurate methods for F- detection. Herein, a dual-mode fluorometric and colorimetric sensor based on MIL-53(Fe)-CQDs@SiO2 is synthesized using a step-by-step self-assembly method. Notably, the introduced carbon quantum dots (CQDs) accelerate the charge transfer and activate the intrinsic active sites of MIL-53(Fe), thereby enhancing the peroxidase-like activity of MIL-53(Fe). Meanwhile, CQDs as a functional group can also impart fluorescence ability to MIL-53(Fe), and the outer SiO2 acts as the start switch controlling the peroxidase-like activity and fluorescence of MIL-53(Fe)-CQDs@SiO2. Benefiting from the peroxidase-like activity and fluorescence ability of MIL-53(Fe)-CQDs@SiO2, a feasible and effective fluorometric and colorimetric dual-mode analytical method for the specific detection of F- is established. The combination of two analytical platforms improves the accuracy and reliability of the detection method. As expected, both the fluorometric and colorimetric analytical methods exhibit broad linear ranges and low limits of detection, demonstrating the excellent application potential for the detection of F-. Furthermore, mechanistic analysis suggests that SiO2 acts as the recognition site and is etched by F-, thus influencing the absorbance and fluorescence of the system. All in all, the current work provides a sensitive and reliable method for detecting F-.

Herein, a novel porous S-CoO/C composite with spatial confinement effect is synthesized. Notably, doped sulfur can have the reaction with Co site of CoO and trigger the d-p orbital hybridization between 3p orbital of sulfur and 3d orbital of cobalt. The d-p orbital hybridization effect can not only increase the content of oxygen vacancy, but also drive the transformation of Co sites from low to high spin states. Benefitting from these changes, more unpaired electrons are generated in S-CoO/C. As a result, the S-CoO/C exhibits moderate oxidase-like property and excellent peroxidase-like activity. In view of the superb peroxidase-like activity of S-CoO/C, a colorimetric assay is proposed for detecting H2O2 and hydroquinone using TMB as the substrate, and developed detection methods have great advantage being a low LOD, a high recovery and a broad linear range. Furthermore, established colorimetric assay displays excellent analysis performance even in real samples.

To address the limitations of poor dispersion, slow charge transfer, and insufficient stability of Co-based catalysts in peroxymonosulfate (PMS) activation for antibiotic degradation, we innovatively modified Co3O4 surface with phytic acid. Subsequently, the catalytic performance of the modified catalyst (denoted as P-Co3O4-2) for PMS activation for sulfamethoxazole degradation was systematically explored. Interestingly, the phytic acid modification significantly can enrich surface hydroxyl groups and oxygen vacancies on Co3O4. The increased hydroxyl groups can promote the hydrophilicity and aqueous dispersion of P-Co3O4-2, while the enhanced oxygen vacancies can accelerate metal valence cycle and interfacial charge transfer. As a result, the P-Co3O4-2 can effectively activate PMS to generate free radicals (SO4•– and •OH) and high-valent metal-oxo species (Co4+=O). In the P-Co3O4-2/PMS system, the highest removal efficiency of sulfamethoxazole was as high as 96.4% within 16 min, and possible pathway of sulfamethoxazole degradation was also studied. Additionally, surface-bound phytic acid acted as a protective layer, suppressing Co leaching and improving catalytic stability. In short, this work provided a novel and effective surface modification strategy for cobalt-based catalysts, offering a promising approach for the remediation of antibiotic-contaminated wastewater.

The pollution problem caused by fluorinated pharmaceutical is a big challenge facing humanity, and it is of great significance to develop an effective remediation method. Herein, Co3O4/g-C3N4 composites with photocatalytic activity are synthesized and employed to activate Peroxymonosulfate (PMS) for the degradation of fluorinated pharmaceutical, and we bring about an interesting discovery that light irradiation can change the activation pathway of PMS. Due to the formation of internal electric field, Co3O4/g-C3N4 composite exhibits very good charge transfer ability and offers more active sites. Thus, Co3O4/g-C3N4 composite can quickly activate PMS to produce SO4 center dot-, achieving effective degradation of ofloxacin with a reaction rate constant as high as 1.6813 min-1. Once visible light irradiation is introduced, notably, the activation pathway of PMS over Co3O4/g-C3N4 composite becomes non-radical mechanism based on 1O2, which is mainly ascribed to the generation of O2 center dot-. More significantly, anti-interference ability of Co3O4/g-C3N4-mediated PMS system is visibly enhanced under the visible light irradiation. To our surprise, consumed electrons of Co3O4/g-C3N4 composite can be restocked by photogenerated carriers, thereby resulting in the regeneration of catalytic activity. During a long-term operation, Co3O4/g-C3N4-mediated PMS system always displays good performance in ofloxacin degradation. In short, current work shared some new insights into the research on the removal of fluorinated pharmaceutical.

It was of great significance to improve the performance of catalysts in peroxymonosulfate (PMS) activation for water pollution control. Herein, Cu 2 O-based catalysts with different exposed facets were synthesized by a feasible method, and later employed for activating PMS to conduct the degradation tests of tetracycline (TC). With the increase of exposed (10 0) facet, the specific surface area of Cu 2 O was improved and the interface charge transfer resistance was reduced. More interestingly, benefiting from the exposure of (100) facet, the electron -donating ability of Cu 2 O was boosted, and the adsorption energy of PMS over Cu 2 O was also reduced, thereby creating favorable conditions for PMS activation. As guessed, Cu 2 O-1 with (100) facet can quickly activate PMS to achieve the effective degradation of TC, and the highest removal efficiency of TC over Cu 2 O-1 can be up to 97.56 % within 15 min. Furthermore, Cu 2 O-1 with good anti -interference showed satisfactory reusability, and the degradation intermediates of TC were the low toxic or nontoxic. In the Cu 2 O-1/PMS system, various reactive oxygen species were detected, including SO 4 center dot - , OH center dot , O 2 center dot - and 1 O 2 , and wherein the contribution of 1 O 2 to TC degradation was the greatest. In short, current work shared some valuable insights into persulfate-based advanced oxidation processes.

Herein, a simple method for effective treatment of organic wastewater containing ofloxacin is proposed. Specifically, sulfur-doped Co3O4 (abbreviated as S-Co3O4) is first prepared and used then as a mediator to activate peroxymonosulfate (PMS). The sulfur doping can facilitate the conversion of low spin state Co to high spin state Co, thereby reducing the work function of Co3O4 to improve internal electron escape probability. Meanwhile, the sulfur doping also induces to form more oxygen vacancies, decreasing interface resistance and accelerating charge transfer. As a result, the activation efficiency of PMS over S-Co3O4 is enhanced. More importantly, the adsorption energy of PMS over S-Co3O4 is reduced after the sulfur doping, leading to generate more S-Co3O4-PMS* complexes. Due to small activation energy, the S-Co3O4-PMS* complexes can be easily decomposed into SO4- and O-1(2). As predicted, the S-Co3O4-mediated PMS system shows excellent performance in ofloxacin degradation, and the removal efficiency is as high as 96.4 % within 20 min. In the S-Co3O4-2-mediated PMS system, the contribution rate of active species for ofloxacin degradation follows an order of SO4- > O-1(2) > Co4+O > OH. Furthermore, the S-Co3O4-2-mediated PMS system with good stability exhibits strong removal ability towards other organic pollutants.