A fluorescent DNA based probe for Hg(II) based on thymine-Hg(II)-thymine interaction and enrichment via magnetized graphene oxide.

The authors describe a fluorometric assay for the determination of Hg(II). A naphthalimide derivative is used as a label for a thymine (T) rich ssDNA, and graphene oxide magnetized with Fe3O4 nanoparticles acts as a quencher and preconcentrators. In the absence of Hg(II), the labeled ssDNA does not separate from the magnetized graphene oxide. As a result, fluorescence is fully quenched. In the presence of Hg(II), a T-Hg(II)-T link is formed dues to the highly affinity between T and Hg(II). Hence, fluorescence is restored. The assay has a linear response in the 1.0 to 10.0 nM Hg(II) concentration range, and a 0.65 nM detection limit. The method is selective and sensitive. It was applied to the analysis of spiked environmental water samples, and data agreed well with those obtained by atomic fluorescence spectrometry. Graphical abstract Strategy of a fluorescent probe for detecting Hg(II). The method has a 0.65 nM detection limit and is selective. MGO: magnetized graphene oxide, AHN: a fluorescent derivative of naphthalimide.

A Fluorescence Sensor for Lead (II) Ions Determination Based on Label-Free Gold Nanoparticles (GNPs)-DNAzyme Using Time-Gated Mode in Aqueous Solution.

This paper describes a label-free 17E DNAzyme-based time-gated fluorescence sensor for Pb2+ detection by unmodified gold nanoparticles (GNPs) and a terbium ternary complex. The fluorophore that used in this paper is a terbium ternary complex. Its signal can be measured in a time-gated manner which could eliminate most of the unspecific fluorescent background. It is well known that unfolded single-stranded DNA (ssDNA) could be adsorbed on GNPs while double-stranded DNA could not. The cleavage of the substrate by the 17E DNAzyme in the presence of Pb2+ causes the release of ssDNA from the 17E-17S duplex to be absorbed onto GNPs, preventing the aggregation of GNPs and then leading to a fluorescence decrease of terbium ternary complex. By means of this method, the authors have successfully detected Pb2+ over a range of 10 nM to 2500 nM with a detection limit of 1.7 nM. The sensor also exhibited good selectivity. The sensor provided a simple, cost-effective, rapid and sensitive measurement tool for Pb2+ detection.

"Turn-on" fluorescent sensor for Hg2+ based on single-stranded DNA functionalized Mn:CdS/ZnS quantum dots and gold nanoparticles by time-gated mode.

An ultrasensitive "turn-on" fluorescent sensor was presented for determination of Hg(2+). This method is mainly based on Hg(2+)-induced conformational change of a thymine-rich single-stranded DNA. The water-soluble long-lifetime fluorescence quantum dot (Mn:CdS/ZnS) acted as the fluorophore, which was labeled on a 33-mer thymine-rich single-stranded DNA (strand A). The gold nanoparticles (GNPs) functionalized 10-mer single-stranded DNA (strand B) is selected as the quencher to quench the fluorescence of Mn:CdS/ZnS. Without Hg(2+) in the sample solution, strands A and B could form hybrid structures, resulting in the fluorescence of Mn:CdS/ZnS being decreased sharply. When Hg(2+) is present in the sample solution, Hg(2+)-mediated base pairs induced the folding of strand A into a hairpin structure, leading to the release of GNPs-tagged strand B from the hybrid structures. The fluorescence signal is then increased obviously compared with that without Hg(2+). The sensor exhibits two linear response ranges between fluorescence intensity and Hg(2+) concentration. Meanwhile, a detection limit of 0.18 nM is estimated based on 3α/slope. Selectivity experiments reveal that the fluorescent sensor is specific for Hg(2+) even with interference by high concentrations of other metal ions. This sensor is successfully applied to determination of Hg(2+) in tap water and lake water samples. This sensor offers additional advantage to efficiently reduce background noise using long-lifetime fluorescence quantum dots by a time-gated mode. With excellent sensitivity and selectivity, this sensor is potentially suitable for monitoring of Hg(2+) in environmental applications.

Highly sensitive strategy for Hg2+ detection in environmental water samples using long lifetime fluorescence quantum dots and gold nanoparticles.

The authors herein described a time-gated fluorescence resonance energy transfer (TGFRET) sensing strategy employing water-soluble long lifetime fluorescence quantum dots and gold nanoparticles to detect trace Hg(2+) ions in aqueous solution. The water-soluble long lifetime fluorescence quantum dots and gold nanoparticles were functionalized by two complementary ssDNA, except for four deliberately designed T-T mismatches. The quantum dot acted as the energy-transfer donor, and the gold nanoparticle acted as the energy-transfer acceptor. When Hg(2+) ions were present in the aqueous solution, DNA hybridization will occur because of the formation of T-Hg(2+)-T complexes. As a result, the quantum dots and gold nanoparticles are brought into close proximity, which made the energy transfer occur from quantum dots to gold nanoparticles, leading to the fluorescence intensity of quantum dots to decrease obviously. The decrement fluorescence intensity is proportional to the concentration of Hg(2+) ions. Under the optimum conditions, the sensing system exhibits the same liner range from 1 × 10(-9) to 1 × 10(-8) M for Hg(2+) ions, with the detection limits of 0.49 nM in buffer and 0.87 nM in tap water samples. This sensor was also used to detect Hg(2+) ions from samples of tap water, river water, and lake water spiked with Hg(2+) ions, and the results showed good agreement with the found values determined by an atomic fluorescence spectrometer. In comparison to some reported colorimetric and fluorescent sensors, the proposed method displays the advantage of higher sensitivity. The TGFRET sensor also exhibits excellent selectivity and can provide promising potential for Hg(2+) ion detection.

Appropriate oxygen vacancies and Mo-N bond synergistically modulate charge transfer dynamics of MoO3-x/S-CN for superior photocatalytic disinfection: Unveiling synergistic effects and disinfection mechanism.

Highly efficient charge transfer is a critical factor to modulate the photocatalytic activity. However, the conscious modulation of charge transfer efficiency is still a great challenge. Herein, a novel interfacial Mo-N bond and appropriate oxygen vacancies (OVs) modulated S-scheme MoO3-x/S-CN heterojunction was rationally fabricated for efficient photocatalytic disinfection. The results of characterizations and density functional theory (DFT) calculations suggested that the enhanced charge transfer dynamics is ascribed to the optimizing oxygen vacancies density and forming interfacial Mo-N bond. It can improve charge transfer efficiency from 36.4% (MoO3-x) to 52.5% (MoO3-x/S-CN) and produce more reactive oxygen species (ROS), achieving entirely inactivate of 7.60-log E. coli and S. aureus within 50 min and 75 min. Besides, MoO3-x/S-CN can well resist the disturbance from the coexisting substances, and can be applied in a wide pH range, and even authentic water bodies. Monitoring of bacterial antioxidant systems and membrane integrity revealed that bacterial inactivation begins with the oxidation of cell membrane and dies from leakage of intracellular substances and destruction of cell structure. This work provides an inspiration on consciously modulating S-scheme charge transfer efficiency by optimizing oxygen vacancies density and atomic-level interface control for promoting the photocatalytic antibacterial activity.

A sensitive strategy for label-free and time-resolved fluorescence assay of thrombin using Tb-complex and unmodified gold nanoparticles.

Gold nanoparticles (GNPs) can effectively differentiate the unfolded and folded aptamer, and quench the fluorescence of terbium ternary complexes (Tb-complexes), thus the authors herein report a sensitive strategy for protein detection, using label-free aptamer, Tb-complexes and GNPs. In the presence of thrombin, the aptamer is inclined to form G-quartet, and the folded aptamer cannot adsorb on the surface of GNPs, inducing the GNPs aggregation in the presence of 0.5 mol L(-1) salt. After centrifugation at low speed to remove the aggregated GNPs, the quenching capability of the supernatant for Tb-complexes is decreased. The fluorescence intensity of Tb-complexes increases as the concentration of thrombin increases. Due to the highly specific recognition ability of the aptamer for thrombin and the strong quenching property of GNPs for Tb-complexes, the proposed protocol has good selectivity and high sensitivity for thrombin. Under the optimum conditions, a linear range from 1.0 × 10(-9) M to 1.0 × 10(-8) M is obtained with a detection limit of 0.14 nM, which is much lower than those commonly obtained for colorimetric sensors and some fluorescent sensors. The signal of Tb-complexes can be measured by time-resolved manner which made most of the unspecific fluorescent background signals be eliminated. The proposed sensor has been successfully applied in complicated biological samples for thrombin detection, and it can provide a promising potential for label-free aptamer-based protein detection.

Determination of ammonia-oxidizing bacteria based on time-resolved fluorescence and tandem probe.

To study the ecology of ammonia-oxidizing bacteria (AOB), quantitative techniques are essential. In this report, the authors introduced an innovative method based on time-resolved fluorescence to quantify AOB as a representative of the major functional microorganisms in sewage water treatment. A bifunctional europium complex with the characteristics of long lifetime and intense luminescence was used as labels in the experiments. In the detection, the capture probe and dye-labeled reporter probe could form a two-probe tandem with the target sequence, and the determination of target DNA was done by monitoring the time-resolved fluorescence signals of europium complex-labeled reporter probe left on the glass slide surface. The experiment conditions consisting of concentration of capture probe, hybridization temperature, hybridization time and washing time were optimized. This method presents satisfactory specificity to common bacteria such as Nitrobacter winogradskyi, Escherichia coli and Paenibacillus polymyxa. The detection limit was 3.65 × 10(-11)mol L(-1). This detection system enables us to rapidly and sensitively analyze the microbial population variety in sewage water treatment.

Metal-organic framework-derived CuCo/carbon as an efficient magnetic heterogeneous catalyst for persulfate activation and ciprofloxacin degradation.

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.

Integrating the Z-scheme heterojunction and hot electrons injection into a plasmonic-based Zn2In2S5/W18O49 composite induced improved molecular oxygen activation for photocatalytic degradation and antibacterial performance.

The semiconductor-based photocatalysts with local surface plasmon resonance (LSPR) effect can extend light response to near-infrared region (NIR), as well as promote charge-carriers transfer, which provide a novel insight into designing light-driven photocatalyst with excellent photocatalytic performance. Here, we designed cost-effective wide-spectrum Zn2In2S5/W18O49 composite with enhanced photocatalytic performance based on a dual-channel charge transfer pathway. Benefiting from the synergistic effect of Z-scheme heterostructure and unique LSPR effect, the interfacial charge-carriers transfer rate and light-absorbing ability of Zn2In2S5/W18O49 were enhanced significantly under visible and NIR (vis-NIR) light irradiation. More reactive oxygen species (ROS) were formed by efficient molecular oxygen activation, which were the critical factors for both Escherichia coli (E. coli) photoinactivation and tetracycline (TC) photodegradation. The enhancement of molecular oxygen activation (MOA) ability was verified via quantitative analyses, which evaluated the amount of ROS through degrading nitrotetrazolium blue chloride (NBT) and p-phthalic acid (TA). By combining theoretical calculations with diverse experimental results, we proposed a credible photocatalytic reaction mechanism for antibiotic degradation and bacteria inactivation. This study develops a new insight into constructing promising photocatalysts with efficient photocatalytic activity in practical wastewater treatment.

Insights into the role of reactive oxygen species in photocatalytic H2O2 generation and OTC removal over a novel BN/Zn3In2S6 heterojunction.

Developing photocatalysts with superior performance to generate hydrogen peroxide (H2O2) and degrade oxytetracycline (OTC) is an effective strategy for the treatment of energy crisis and water purification. Herein, BN nanosheets were anchored onto the Zn3In2S6 microspheres for the research. Experimental and density functional theory (DFT) results demonstrate that due to different work functions and unique 2D/2D contact, the electron is spatially separated in BN/Zn3In2S6 nanocomposite, which increases the electron transfer efficiency from 43.7% (Zn3In2S6) to 55.6% (BN/ZIS-4). As a result, BN/ZIS-4 with optimal ratio of BN and Zn3In2S6 exhibits the highest OTC degradation efficiency (84.5%) and H2O2 generation rate (115.5 µmol L-1) under visible light illumination, which is 2.2 and 2.9 times than that of pristine Zn3In2S6. H2O2 generation is dominated by two pathways: two-step single-electron process (O2 → ∙O2- → H2O2) and another way (O2 → ∙O2- → 1O2 → H2O2). In the process of degrading OTC, ∙O2-, 1O2 and ∙OH are regarded as the main active species. This work offers a new insight for designing efficient, stable and reusable photocatalysts to solve current environmental conundrums.

Surface-functionalization-dependent optical properties of II-VI semiconductor nanocrystals.

We report a study of the surface-functionalization-dependent optical properties of II-VI zinc-blende semiconductor nanocrystals on the basis of ligand-exchange chemistry, isomaterial core/shell growth, optical spectroscopy, transmission electron microscopy, and X-ray powder diffraction. Our results show that the transition energy and extinction coefficient of the 2S(h3/2)1S(e) excitonic band of these nanocrystals can be strongly modified by their surface ligands as well as ligand associated surface atomic arrangement. The oleylamine exchange of oleate-capped zinc-blende II-VI nanocrystals narrows the energy gap between their first and second excitonic absorption bands, and this narrowing effect is size-dependent. The oleylamine exchange results in the quenching, subsequent recovery, and even enhancing of the photoluminescence emission of these II-VI semiconductor nanocrystals. In addition, the results from our X-ray powder diffraction measurements and simulations completely rule out the possibility that oleate-capped zinc-blende CdSe nanocrystals can undergo zinc-blende-to-wurtzite crystal transformation upon ligand exchange with oleylamine. Moreover, our theoretical modeling results suggest that the surface-functionalization-dependent optical properties of these semiconductor nanocrystals can be caused by a thin type II isomaterial shell that is created by the negatively charged ligands (e.g., oleate and octadecyl phosphonate). Taking all these results together, we provide the unambiguous identification that II-VI semiconductor nanocrystals exhibit surface-functionalization-dependent excitonic absorption features.

A novel bifunctional europium chelate applied in quantitative determination of human immunoglobin G using time-resolved fluoroimmunoassay.

The authors demonstrate herein a novel time-resolved fluoroimmunoassay (TRFIA) protocol for quantification of human IgG with the new bifunctional chelate Eu(TTA)3(5-NH2-phen) (ETNP) labeling the goat anti-human IgG. The immunoassay was conducted by following the typical procedure for sandwich-type immunoreactions. Goat anti-human IgG was immobilized on aldehyde-modified glass slides. The human IgG analyte was first captured by the primary antibody and then sandwiched by a secondary antibody labeled with the chelate ETNP. The experimental procedure was simple to follow and gave desirable levels of sensitivity and low limits of detection. To the best of our knowledge, this is the first application of the new chelate, ETNP, in an immunoassay. In comparison to typical organic, fluorescent compounds and other lanthanide fluorescent chelates used in immunoassay, the detection sensitivity of our method using ETNP chelate in the solid phase was greatly improved and a concentration of human IgG about 5 µg/L could be detected under optimal conditions. The main result of this work shows that the new chelate ETNP can be applied as a powerful fluorescent labeling material for constructing ultrasensitive TRFIAs. The detection of human IgG, using ETNP as the chelate, is a model example of the effectiveness of this immunoassay. Many other types of antigen-antibody immunoassays should be possible using the protocol described herein.

2D/2D Heterojunction systems for the removal of organic pollutants: A review.

Photocatalysis is considered to be an effective way to remove organic pollutants, but the key to photocatalysis is finding a high-efficiency and stable photocatalyst. 2D materials-based heterojunction has aroused widespread concerns in photocatalysis because of its merits in more active sites, adjustable band gaps and shorter charge transfer distance. Among various 2D heterojunction systems, 2D/2D heterojunction with a face-to-face contact interface is regarded as a highly promising photocatalyst. Due to the strong coupling interface in 2D/2D heterojunction, the separation and migration of photoexcited electron-hole pairs are facilitated, which enhances the photocatalytic performance. Thus, the design of 2D/2D heterojunction can become a potential model for expanding the application of photocatalysis in the removal of organic pollutants. Herein, in this review, we first summarize the fundamental principles, classification, and strategies for elevating photocatalytic performance. Then, the synthesis and application of the 2D/2D heterojunction system for the removal of organic pollutants are discussed. Finally, the challenges and perspectives in 2D/2D heterojunction photocatalysts and their application for removing organic pollutants are presented.

A novel bifunctional europium complex as a potential fluorescent label for DNA detection.

A bifunctional europium complex of Eu(TTA)(3)(5-NH(2)-phen) using 2-thenoyltrifluoroacetonate (TTA) and 5-amino-1,10-phenanthroline (5-NH(2)-phen) as ligand reagents was applied in DNA detection assays for the first time. The complex has a long fluorescence lifetime, high fluorescence quantum yield, and is easy to label oligonucleotides for time-resolved fluorescence bioanalysis. A two-probe tandem DNA hybridization assay including capture DNA(1), probe DNA(2), and target DNA(3) was employed to detect microbial pathogens. The DNA sequences in the assay were designed using software Primer Premier 5.0 based on published specific nucleotide sequences of Staphylococcus aureus and Escherichia coli. 3'-Amino-modified capture DNA(1) was covalently immobilized on the common glass slide surface and the 5'-amino-modified probe DNA(2) was combined with the functionalized Eu(TTA)(3)(5-NH(2)-phen) via glutaraldehyde. The detection was done by monitoring the fluorescence intensity from the glass surface after the hybridization reaction with complementary target DNA(3). The optimal concentration of capture DNA(1) of 1.0 x 10(-6) mol l(-1) dropped onto the glass slides and optimal hybridization temperatures of 48 degrees C and 39 degrees C respectively for Staphylococcus aureus and Escherichia coli were obtained. The proposed DNA detection system showed higher sensitivity than such a complex doped nanoparticle-based detection system in our previous study for the better uniformity and dispersity of monomolecular labels. The sensing system presented a short hybridization time of 2 h, satisfactory stability, and high selectivity. The results demonstrate that this complex might be a potentially excellent dye in area of biochemical analysis.

In suit constructing 2D/1D MgIn2S4/CdS heterojunction system with enhanced photocatalytic activity towards treatment of wastewater and H2 production.

A novel visible-light-driven 2D/1D MgIn2S4/CdS catalyst with heterostructure was fabricated for sewage treatment and energy conversion. In this study, MIS/CdS-0.3 heterostructure catalyst displayed the remarkable photocatalytic performance, which could reduce about 100% of Cr(VI) within 30 min and decompose approximately 95.98% of oxytetracycline (OTC) after 60 min. Meanwhile, the degradation details and possible decomposition pathways for OTC solution were further verified by 3D EEM and LC-MS. Moreover, the as-obtained 2D/1D MgIn2S4/CdS hybrid composites signally promoted the hydrogen evolved in the light illumination at 420 nm. Meanwhile, some consequences based on various characterization technologies confirmed that the significant photo-induced charge separation rate is a crucial factor in the enhancement of photocatalytic capacity. The intimate contact and the formation of heterostructure between 2D MgIn2S4 nanosheets and 1D CdS nanorods with matched band gaps were beneficial for charge migration. Moreover, the band structures and the density of states (DOS) of MgIn2S4 and CdS were obtained based on density functional theory (DFT). In addition, the results of cycling experiments, XRD spectra and PL showed that the composition and performance of the composite are well-maintained, suggesting the great recyclability and stability. This work indicated that developing a 2D/1D heterostructure photocatalyst offers a cracking approach to enhance the photocatalytic property of semiconductor-based catalysts for pollutant removal and the generation of clean energy.

Photocatalytic degradation of sulfamethazine using a direct Z-Scheme AgI/Bi4V2O11 photocatalyst: Mineralization activity, degradation pathways and promoted charge separation mechanism.

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.

Highly sensitive sensor for detection of NADH based on catalytic growth of Au nanoparticles on glassy carbon electrode.

In this work, an electrochemical dihydronicotinamide adenine dinucleotide (NADH) sensor based on the catalytic growth of Au nanoparticles (Au NPs) on glassy carbon electrode was developed. Catalyzed by Au NPs immobilized on pretreated glassy carbon electrode, the reduction of AuCl(4)(-) in the presence of hydroquinone and cetyltrimethyl ammonium chloride led to the formation of enlarged Au NPs on the electrode surface. Spectrophotometry and high-resolution scanning electronic microscope (SEM) analysis of the sensor morphologies before and after biocatalytic reaction revealed a diameter growth of the nanoparticles. The catalytic growth of Au NPs on electrode surface remarkably facilitated the electron transfer and improved the performance of the sensor. Under optimal conditions, NADH could be detected in the range from 1.25 x 10(-6) to 3.08 x 10(-4) M, and the detection limit was 2.5 x 10(-7) M. The advantages of the proposed sensor, such as high precision and sensitivity, fast response, low cost, and good storage stability, made it suitable for on-line detection of NADH in complex biological systems and contaminant degradation processes.

Construction of a high-performance photocatalytic fuel cell (PFC) based on plasmonic silver modified Cr-BiOCl nanosheets for simultaneous electricity production and pollutant removal.

The development of high-performance photocatalytic fuel cells (PFCs) is seriously hampered by poor light utilization rates and low charge carrier transfer efficiency. Herein, we have experimentally obtained plasmonic Ag modified Cr-BiOCl (Cr-BOC/Ag) with high visible light photocatalytic activity and provided direct evidence for the substantially enhanced catalytic activity in metal-semiconductor photocatalysts. The experimental results revealed that the Cr doping and Ag modification could not only extend the photo absorption of BiOCl from the UV to the visible light region but could also greatly increase the generation and transfer rate of charge carriers because of its narrowed band gap and the localized surface plasmon resonance (LSPR) effect of metallic Ag. Under visible light irradiation, the Cr-BOC/Ag showed a remarkable enhancement in the PFC performance when the optimum contents of Cr doping and Ag loading was 14.4% and 4%, respectively. The trapping experiments and multiple characterizations demonstrated that the advantageous combination of the Cr doping effect and SPR effect induced by the Ag nanoparticles is responsible for the high generation rate of oxidative species and effective charge carrier transfer. By using RhB as fuel, approximately 75.1% color removal efficiency and 8.38% coulombic efficiency were obtained under visible light irradiation for 240 min, which are higher than those of MO and TC. In addition, the Jsc and Voc of the Cr-BOC/Ag photoanode were measured to be 0.0073 mA cm-2 and 0.543 V.

Construction of 2D heterojunction system with enhanced photocatalytic performance: Plasmonic Bi and reduced graphene oxide co-modified Bi5O7I with high-speed charge transfer channels.

The efficient electron-hole charge pair separation, ultra-fast electron migration and excellent light harvest capacity are essential for semiconductor photocatalyst with superior photocatalytic performance. In this study, we constructed layered 2D/2D heterojunction composite of Bi@Bi5O7I/rGO (BiBGOI) through a facile surface charge mediated self-assembly strategy. The unique 2D/2D heterostructure with face to face contact can increase the contact area and generate a large amount of charge transfer nanochannels in the interfacial heterojunction, resulting in the enhancement of photocatalytic activity. Addition of semimetal Bi can enhance light absorption, and the local electromagnetic field dominated by SPR effect is favorable for photoinduced charge pair separation. The novel composite showed superior photocatalytic performance for decomposing levofloxacin (LVFX), which was attributed to the unique 2D/2D structure and SPR effect. The enhanced mineralization ability of the novel composite was ascribed to the strong oxidization ability of photoinduced holes, further evaluating high charge pair separation efficiency. In addition, the strong adsorption capacity of rGO for LVFX molecules can enable active radicals transfer into the surface to decompose it. This work will shed light on constructing 2D/2D heterojunction system assisted with SPR effect for the practical application in removal of organic pollutants.

Constructing magnetic and high-efficiency AgI/CuFe2O4 photocatalysts for inactivation of Escherichia coli and Staphylococcus aureus under visible light: Inactivation performance and mechanism analysis.

Magnetic materials usually exhibit advanced performance in many areas for their easy separating and recycle ability. In this study, silver iodide/copper ferrite (AgI/CuFe2O4) catalysts with excellent magnetic property were successfully synthesized and characterized by a series of techniques. Two typical bacteria Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were applied to estimate the photocatalytic inactivation performance of obtained AgI/CuFe2O4 catalysts. Results revealed that the AgI/CuFe2O4 (12.5% AgI) composite could absolutely inactivate 3 × 109 CFU/mL E. coli and 2.7 × 108 CFU/mL S. aureus cells severally in 50 min and 40 min under visible light irradiation, which showed a much higher photo-disinfection activity than monomers. Transmission electron microscopy was used to study the biocidal action of this nanocatalyst, the results confirmed that the treated E. coli cells were damaged, the nanocatalyst permeated into cells and resulting in death of cells. Besides, it was found that the destruction of bacterial membrane together with substantial leaked potassium ion (K+) which caused by the photo-generated reactive species superoxide radical (O2-) and holes (h+) could be the direct disinfection principles. For a deep insight into practical applications, the influences of different catalyst concentrations and reaction pH were also taken into discussion in details. The overall results indicated the novel photocatalyst with strong redox capacity and outstanding reusability can be widely employed in bacteria elimination.