A novel Z-scheme system of CeO2–Ag/AgBr heterostructure photocatalyst exhibits excellent ability to eliminate ciprofloxacin under visible light irradiation.
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•Novel Z-scheme ...CeO2–Ag/AgBr photocatalysts were prepared.•Superior photocatalytic activity for the degradation of ciprofloxacin (CIP) refractory pollutants was obtained.•The factors affecting the photocatalytic performance were investigated.•A plausible degradation pathway for CIP was proposed.•A Z-scheme photocatalytic mechanism was proposed.
In this study, CeO2–Ag/AgBr composite photocatalysts with a Z-scheme configuration were fabricated by in situ interspersal of AgBr on CeO2 and subsequent photoreduction process. The CeO2–Ag/AgBr composites exhibited enhanced photocatalytic activity for the photodegradation of ciprofloxacin (CIP) under visible light irradiation. The effects of initial CIP concentration and various inorganic salts were investigated in detail. Three-dimensional excitation–emission matrix fluorescence spectra were used to further monitor the CIP molecule degradation. Plausible degradation pathways for CIP were proposed based on LC-MS instruments. Photoluminescence, electrochemical impedance spectroscopy, and photocurrent tests indicated the rapid transfer and migration of electrons–holes can be achieved in this ternary photocatalytic system. The enhanced photocatalytic performances of CeO2–Ag/AgBr could be credited to the accelerated interfacial charge transfer process and the improved separation of the photogenerated electron–hole pairs. The existence of a small amount of metallic Ag is conducive to the formation of a stable Z-scheme photocatalytic system. This work would pave the route for the design of novel Z-scheme photocatalytic systems for application in solar-to-fuel conversion and photocatalytic water treatment.
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•CoB/CNs Schottky junction with interfacial Co-N bond was prepared;•CoB/CNs presents excellent performance for photocatalytic S. aureus inactivation;•Interfacial Co-N bond can ...efficiently modulate the charge transfer dynamics;•Two-step single-electron induced O2 reduction (O2 → ·O2– → H2O2) is enhanced.
Interfacial engineering plays a critical role in modulating the electron transfer dynamics of photocatalysis, but has been rarely explored. Herein, a novel cobalt boride/graphitic carbon nitride nanosheet (CoB/CNs) Schottky junction with interfacial Co-N bond was successfully prepared to uncover the function of interfacial chemical bond in photocatalytic antibacterial process. Density functional theory (DFT) calculation and experimental investigation demonstrate that the interfacial Co-N bond can act as an electron transfer channel to efficiently steer the electron transfer from CNs to CoB, and then an upward band bending with the height of 0.26 eV is formed in CoB/CNs Schottky junction. The formed upward band bending can rapidly separate the photogenerated electron-hole pairs by preventing electrons from flowing back to the CNs, which causes the surface electron transfer efficiency (ηtrans) to increases from 41.8% (CNs) to 57.7% (CoB/CNs-2). Rotating disk electrode (RDE) results demonstrate that compared with CNs (n = 2.38), the oxygen reduction reaction in CoB/CNs-2 (n = 2.19) is more selective to a two-electron transfer route. Meanwhile, further research on reactive oxygen species reveals that it is an indirect two-step single-electron oxygen reduction process, which is beneficial for the generation of ·O2– and H2O2. As a result, 7 × 107 CFU/mL of Staphylococcus aureus (S. aureus) can be completely inactivated by CoB/CNs-2 with 125 min under visible light irradiation. It is expected that our work will provide some guidance for the exploitation of more advanced hybrid photocatalysts system through interfacial engineering.
Herein, the authors synthesis an efficient and easily recycled CuCo/C catalyst through one-step carbonization of Cu@Co-MOF-71 (Abbreviated as Cu@Co-MOF in this work) precursor. The prepared CuCo/C ...has a high degradation efficiency of 90% for ciprofloxacin (CIP) by activating PMS in a wide value of pH 3–9 within 30 min. After pyrolysis, the carbon matrix as a dispersant can promote the highly uniform distribution of active metals. Additionally, the CIP removal efficiency was 85% after four cycles and the catalyst was easily separated from the solution by using magnets, showing the good stability and reusability. To further study the superiority of CuCo/C activated PMS in degrading CIP, the factors such as pH, the dosage of PMS and catalyst, temperature, inorganic ions and pollutant (CIP) concentration were investigated. Furthermore, the Liquid chromatography-mass spectrometry (LC-MS) was utilized to analyze the intermediate products and possible degradation pathways of CIP. Typically, the quenching experiments and electron paramagnetic resonance (EPR) technology were investigated to confirm the main reaction species including SO4▪−, OH▪ and O2▪− radicals as well as nonradical (1O2). This work put forward a simple method for synthesis of metal-organic framework (MOF) derived catalysts and its application in treatment of organic pollutants.
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•The CuCo/C catalyst was prepared by a facile one-step carbonization method.•The carbon derived from the organic ligands in the MOFs facilitates the highly distribution of active metals.•The CuCo/C catalyst showed a little bit higher reaction stoichiometric efficiency (RSE).•A high degradation efficiency for CIP by activating PMS.•This work put forward a simple method for synthesis of MOFs derived catalysts.
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•Novel direct Z-scheme AgI/Bi4V2O11 photocatalysts were prepared.•A superior photocatalytic activity for the degradation of SMZ refractory pollutants.•A plausible degradation pathway ...for SMZ was proposed.•The fabrication Z-scheme heterostructure play a central role in promoting charge separation and active radical generation.
Z-scheme heterojunction can not only promote the separation of photogenerated carriers, but also retain the strong redox potential of the system, which would greatly improve the photocatalytic performance of catalyst. Herein, a Z-scheme AgI/Bi4V2O11 heterojunction photocatalyst was prepared by a hydrothermal process combined with in situ coprecipitation process. Multiple techniques were employed to investigate the morphology, composition, chemical and electronic properties of the as-prepared samples. The obtained Z-scheme AgI/Bi4V2O11 heterojunction photocatalyst exhibited remarkably enhanced photocatalytic performance towards sulfamethazine (SMZ) degradation under visible light irradiation. Especially, the 20 wt% AgI/Bi4V2O11 composites exhibited the highest photocatalytic activity for sulfamethazine (SMZ) degradation and 91.47% SMZ would be eliminated within 60 min. In comparison with NO3− and SO42−, the presence of Cl− and HCO3− presented more obviously inhibition effects on SMZ degradation. The possible degradation pathways of SMZ were speculated by identifying degradation intermediates. O2−, h+ and OH all involved in the photocatalytic degradation SMZ. The highly enhanced photocatalytic performance might be attributed to form Z-scheme junction between AgI and BVO, which are conducive to the efficient charges separation and maintain high redox potential. This work enriches Bi4V2O11-based Z-scheme heterojunction photocatalytic system and provides a reference for the preparation of effective Z-scheme junction photocatalysts.
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•Novel magnetically separable Ag2O/ZnFe2O4 p-n heterostructure photocatalysts were fabricated.•Ag2O/ZnFe2O4 composites display outstanding photoactivity for BPA degradation under ...visible light irradiation.•The band offsets in p-n heterostructure play a central role in promoting charge separation and performance enhancement.•Ag2O/ZnFe2O4 composites bring new insights into the comprehension and fabrication of novel p-n heterostructure photocatalysts.
The fabrication of highly efficient catalysts with easy recyclability has received great attention in the development of realistic photocatalytic applications. Herein, a magnetically separable Ag2O/ZnFe2O4 p-n heterostructure photocatalyst was fabricated and utilized for the degradation of BPA under visible light irradiation. Results show that the obtained AZ-3 composite possesses the optimal performance, which is about 2.33-fold and 34.45-fold higher than that of Ag2O and ZnFe2O4, respectively. The enhanced performance is attributed to the rapid separation of photogenerated electrons and holes caused by the built-in electric field between p-type Ag2O and n-type ZnFe2O4, as detailedly evidenced by photoelectrochemical measurements. Moreover, density functional theory (DFT) calculations show that the electrons around the contact interface of Ag2O and ZnFe2O4 will be redistributed after their hybridization, while the investigation on energy band alignment further indicates that a type-II band alignment with ΔECBO = 0.16 eV and ΔEVBO = 0.65 eV is formed in this p-n heterostructure, which provides a solid support for the reaction mechanism. This work gives deep insights into the charge transfer properties of p-n heterostructure systems and opens new vistas for the construction of highly efficient and magnetically separable photocatalysts.
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•The formation of Schottky barrier in MONC-3 can inhibit the backflow of electrons.•MONC-3 can convert the absorbed light energy into local high temperature.•Photodynamic and ...photothermal effects synergistically lead to bacterial death.•DFT calculation clarifies the charge transfer mechanism in Schottky heterojunction.
Developing green and highly efficient water disinfection technique is of great importance to public health. Herein, a near-infrared (NIR) light-triggerable thermo-sensitive defective molybdenum oxide-nitrogen doped carbon (MoO3-x/NCNs) composite was fabricated and applied to water disinfection. With the synergy of photodynamic and photothermal effects, the MoO3-x/NCNs achieve a rapid and effective inactivation of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as compared to photocatalytic treatment or thermal catalytic alone. Particularly, MONC-3 with optimal ratio can completely inactivate 7.6 log of E. coli and S. aureus within 60 min and 100 min, respectively. The MONC-3 hybrid exhibits efficient charge separation and migration ability due to the formation of Schottky heterojunction, resulting in the highly enhanced O2− (11.34 × 10−10 M) generation activity. Meanwhile, excellent NIR light absorption and photothermal conversion efficiency (52.6%) of MONC-3 can generate local high temperature to promote photocatalytic reaction rate and destruct the bacterial integrity. The monitoring of cell damage process confirmed the irreversible death of bacteria. Based on density functional theory (DFT) calculation, the antibacterial mechanism and Schottky effect were clarified. This work provides new insights for constructing a water disinfection strategy based on plasma-induced photothermal synergy catalysis.
A magnetic multi-wall carbon nanotube (MMWCNT) nanocomposite was synthesized and was used as an adsorbent for removal of cationic dyes from aqueous solutions. The MMWCNT nanocomposite was composed of ...commercial multi-wall carbon nanotubes and iron oxide nanoparticles. The properties of this magnetic adsorbent were characterized by scanning electron microscopy, X-ray diffraction and BET surface area measurements. Adsorption characteristics of the MMWCNT nanocomposite adsorbent were examined using methylene blue, neutral red and brilliant cresyl blue as adsorbates. Experiments were carried out to investigate adsorption kinetics, adsorption capacity of the adsorbent and the effect of adsorption dosage and solution pH values on the removal of cationic dyes. Kinetic data were well fitted by a pseudo second-order model. Freundlich model was used to study the adsorption isotherms. The prepared MMWCNT adsorbent displayed the main advantage of separation convenience compared to the present adsorption treatment.
•The CMCN2/PMS system exhibited excellent catalytic performance for NB removal.•The mechanism of active species has been investigated in details.•The CMCN2/PMS system show robust stability and wide ...pH adaptation of 3–10.•The real wastewater containing nitrobenzene derivatives is efficiently degraded.
In this study, the MnCo2O4/g-C3N4 (CMCN2) is used to activate peroxymonosulfate (PMS), for treating nitrobenzene (NB) and industrial wastewater containing nitrobenzene homologue. Different from traditional sulfate radical-based advanced oxidation processes (SR-AOPs), high-valent metal-oxo species (MIV(O)/MV(O)) is a major reactive component via dimethyl sulfoxide (DMSO) as a verify compound. The mechanism is speculated that the bond of nitrogen–metal = oxygen (N–M = O) activates PMS to form MIV(O)/MV(O) during sacrificial oxidation. The quenching experiments and electron spin resonance (ESR) confirm that CMCN2 activated PMS to form OH and SO4–. The Langmuir-Hinshelwood model conforms to the NB degradation curve, and the best removal efficiency is 96.7% in 240 min. The CMCN2/PMS system has excellent stability between pH 3–10. Also, the CMCN2/PMS system exhibited satisfactory removal of NB in the presence of inorganic anions and natural organic matters. The treatment effect of industrial wastewater containing phenyl homologues shows that CMCN2/PMS has a high mineralization capacity. This study details the electron transfer during the formation of active components and provides new ideas for selecting active ingredients that degrade phenyl pollutants in the field of advanced oxidation.
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•Electron-withdrawing groups functionalized few layer g-C3N4 was prepared.•FCN-12 exhibits excellent performance in PMS photocatalytic activation.•Few layer structure and ...functionalized groups co-boost charge separation.•This work provides comprehensive insights into the role of energy band bending.
In this work, electron-withdrawing groups functionalized few layer graphitic carbon nitride (FCN-12) nanosheet was prepared and utilized for photocatalytic activation of peroxymonosulfate (PMS). Experimental characterization and density functional theory (DFT) calculation reveals that the electronic structure of FCN-12 is efficiently adjusted by forming an upward band bending, as the functionalized carbonyl (C=O) and carboxyl (-COOH) groups can withdraw the electron from the C-N=C skeleton. With the addition of PMS, FCN-12 displays superb photocatalytic activity for chlortetracycline hydrochloride (CTC) degradation, where 83.4% CTC can be degraded within 120 min under visible light irradiation, much higher than that of bulk g-C3N4 (34.3%). Besides, even under the different pH condition and co-existed anions environment, FCN-12/PMS/vis system still exhibits favorable applicability. The boosted catalytic performance is resulted from the collective effect of the few-layer feature and the energy band bending, which leads to the effective migration of photogenerated electron from FCN-12 to PMS via C=O and -COOH groups. This work not only provides an exhaustive insight into the role of energy band bending in electron-withdrawing group functionalized g-C3N4, but also paves the avenue for the development of metal-free photocatalyst-mediated environmental remediation based on PMS activation.
SrTiO3/BiOI heterostructure photocatalysts were successfully fabricated through a facile chemical bath method with assistant of the ethylene glycol, which exhibit an efficient charge separation and ...excellent catalytic ability in removing different refractory pollutants.
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•Novel SrTiO3/BiOI heterojunction photocatalysts were fabricated.•A wider application in the degradation of refractory pollutants.•The factors affecting the photocatalytic performance were investigated.•The degradation process of MO and OTTCH was monitor by 3D EEMs.•The in-depth mechanisms insight of charge separation.
Novel SrTiO3/BiOI heterostructure photocatalysts were successfully fabricated through a facile chemical bath method with assistant of the ethylene glycol. The photocatalysts were applied to minimize methyl orange (MO), bisphenol A (BPA), antibiotic oxytetracycline hydrochloride (OTTCH) under visible light irradiation. The SrTiO3/BiOI composites exhibited excellent photocatalytic performance towards the different refractory pollutants. Especially, the sample of STB-22.12 possessed the best photocatalytic performance in all the obtained catalysts. Several reaction parameters affecting degradation such as initial concentration, ion species were investigated systematically. Three-dimensional excitation–emission matrix fluorescence spectroscopy (3D EEMs) was used to further investigate the MO and OTTCH molecule degradation process. The photocatalytic mechanism over composite photocatalyst is systematically investigated by active species trapping experiments, ESR technique and Mott–Schottky measurements. Moreover, the energy band alignments of SrTiO3/BiOI heterostructure were confirmed via combining DRS and XPS analysis, which provided strong support for the proposed mechanism. This work could provide a deeper insight for the heterojunction catalyst.
