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.

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.

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.

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.

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.

Fabrication of visible-light-driven silver iodide modified iodine-deficient bismuth oxyiodides Z-scheme heterojunctions with enhanced photocatalytic activity for Escherichia coli inactivation and tetracycline degradation.

At present, various organic pollutants and pathogenic microorganisms presented in wastewater have severely threatened aquatic ecosystem and human health. Meanwhile, semiconductor photocatalysis technology for water purification has attracted increasingly significant attention. Herein, we successfully constructed a series of novel visible-light-driven (VLD) Bi4O5I2/AgI hybrid photocatalysts with different AgI amounts. Compared with pristine AgI and Bi4O5I2, Bi4O5I2/AgI with the optimal AgI contents exhibited remarkably enhanced photocatalytic performance in probe experiment for Escherichia coli (E. coli) disinfection and tetracycline (TC) degradation. The efficiency for TC degradation and E. coli inactivation reached 82% and 100% in 30 min, respectively. The enhanced electron-hole separation efficiency was responsible for improved photocatalytic activity. In addition, the destruction process of the chemical structure of TC molecules was further investigated by three-dimensional excitation-emission matrix fluorescence spectra (3D EEMs). The activity and crystal phase of the catalysts did not change significantly after four cycles, demonstrating their excellent recyclability and stability of catalysts. The Ag+ ion leaking experiments, radical trapping experiments and ESR tests demonstrated that OH, O2- and h+ were the main active species in photocatalytic disinfection processes. Furthermore, the photocatalytic mechanism of Bi4O5I2/AgI nanomaterials was discussed in detail in conjunction with the energy band structure, and a reasonable Z-scheme interfacial charge transfer mechanism was proposed. This work is expected to provide an efficient water disinfection method.

Ultrathin BiOCl Single-Crystalline Nanosheets with Large Reactive Facets Area and High Electron Mobility Efficiency: A Superior Candidate for High-Performance Dye Self-Photosensitization Photocatalytic Fuel Cell.

Strong dye adsorption and fast electron transfer are of crucial importance to achieve high conversion efficiency of dye self-photosensitization photocatalytic fuel cells (DSPFCs). In this study, we have experimentally achieved the enhanced cell performance in ultrathin BiOCl{010} (BOC(010)-U) nanosheets and provide an idea to investigate the relationship between the physical structure and the chemical performance of semiconductor materials. Experimental phenomenon showed that the exposed areas of highly active {010} facets were remarkably enhanced with the decrease of the BiOCl thickness. The large area of {010} facets with abundant active sites and open channel characteristic were exposed to facilitate photosensitization process, and the atomically thin structure was designed to speed up electron transfer. By employing 40 mL of 5 mg/L rhodamine B as fuel, it was found that the BOC(010)-U photoanode exhibited superior photovoltaic performance and photocatalytic degradation activity than other materials in the DSPFC system, whose Jsc and Voc were measured to be 0.00865 mA/cm2 and 0.731 V, respectively. Besides, about 72% color removal efficiency and 10.77% Coulombic efficiency were obtained under visible light irradiation for 240 min. The experimental results and multiple characterizations demonstrated that the strong dye adsorption ability and efficient charge migration were responsible for the sustaining generation of photocurrent and enhancement of pollutants degradation activity.

Enhanced photocatalytic activity of CdS/SnS2 nanocomposite with highly-efficient charge transfer and visible light utilization for selective reduction of 4-nitroaniline.

Photocatalytic reduction can be an effective and promising technology for the selective reduction of aromatic nitro organics. In this paper, a novel Z-scheme CdS/SnS2 photocatalyst was well-designed and fabricated via simple in-site reaction process containing thioacetamide as a sulfur sources and cubic CdSnO3 as template. The resulting CdS/SnS2 composite has well-constructed cubic nanostructure of strong adhesion between CdS and SnS2, presenting high absorption to visible light. Importantly, strong charge transfer between the contacting regions of CdS and SnS2 through the intermediate sulfur atoms combined with both metals was generated, which speeds up separation of photogenerated electron and hole. The advantageous combination of high light-harvesting and effective charge transfer is responsible for the excellent photocatalytic activity at the CdS/SnS2 heterointerface. Resultantly, the prepared CdS/SnS2 composites exhibit high conversion efficiency and selectivity on 4-nitroaniline (4-NA) reduction in the aqueous solution containing ammonium formate under visible light irradiation, which can reduce almost all 4-NA within 12 min. Trapping experiments and ESR analysis demonstrated that ammonium formate not only can effectively decrease recombination of photogenerated charge carriers but also react with holes to generate CO2- radicals possessing strong reduction ability. The 4-NA are effectively photo-reduced by the synergistic effect of electrons and CO2- radicals. According to the experimental results, a possible Z-scheme charge transfer mechanism was proposed. Besides, the photo-reduction of aromatic nitro organics possessed different para-groups (p-nitrophenol, nitrobenzene, and p-nitrobenzaldehyde) was also investigated. It is found that the electron-drawing group can decrease the electron density of its para-position nitryl, which quickens the nitro reduction.

A facile strategy to fabricate hollow cadmium sulfide nanospheres with nanoparticles-textured surface for hexavalent chromium reduction and bacterial inactivation.

Exploring morphology and surface structure of semiconductor photocatalyst is crucial for researching their photocatalytic performance. In this paper, hollow CdS nanospheres (CdS-HSs) were successfully fabricated via simple template self-removal strategy. The prepared CdS-HSs were characterized by XRD, SEM, HR-TEM, UV-vis diffuse reflectance spectra (DRS), XPS, photocurrent response (I-T), photoluminescence (PL) and electrochemistry impedance spectroscopy (EIS). It was found that the prepared CdS-HSs have nanoparticles-textured surface composed of ultra-small CdS nanoparticles (∼20 nm) and large surface areas. DRS result demonstrated that the CdS-HSs exhibit strong visible light absorption capacity. The results of photocurrent response, photoluminescence and EIS revealed that hollow structure and nanoparticles-textured surface can effectively increase light reflection effect and decrease recombination rate of electrons and holes. Compared to the traditional CdS, the hollow CdS nanospheres exhibit higher photocatalytic activity on Cr(VI) reduction under visible light irradiation, which are primarily attributed to its rapid separation of electron-hole pairs and improved visible light absorption. Moreover, CdS-HSs was also demonstrated as an effective and potential material on photocatalytic disinfection. The result of mechanism experiments proved that h+, e- and O2- play important roles on the bacteria inactivation.

Enhanced Escherichia coli inactivation and oxytetracycline hydrochloride degradation by a Z-scheme silver iodide decorated bismuth vanadate nanocomposite under visible light irradiation.

Novel Z-scheme AgI/BiVO4 photocatalysts were fabricated by a chemical deposition-precipitation approach. The photocatalytic activities of the obtained catalysts were evaluated by disinfection of Escherichia coli (E. coli) and degradation of oxytetracycline hydrochloride (OTC-HCl) under visible-light irradiation. The BA3 (contained 9.09% of AgI) exhibited the highest photocatalytic activity and maintained good stability. It could completely inactivate 7.0×107 CFU/mL of E. coli in 50 min and degrade 80% of OTC-HCl in 60 min. The enhanced photocatalytic activity of AgI/BiVO4 composites could be ascribed to the lower recombination rate of electron-hole pairs. Meanwhile, radical trapping experiments revealed that the superoxide radical (O2-) and holes (h+) were the dominant reactive species in photo-disinfection process. Furthermore, the effects of bacterial initial concentration and inorganic anions were also investigated to optimize the photocatalyst for practical application. This study will give a new insight to construct the effective Z-scheme system for bacterial inactivation and organic pollutants degradation.

Construction of highly efficient and stable ternary AgBr/Ag/PbBiO2Br Z-scheme photocatalyst under visible light irradiation: Performance and mechanism insight.

In this work, the novel ternary AgBr/Ag/PbBiO2Br Z-scheme photocatalysts were synthesized via a CTAB-assisted calcination process. The AgBr/Ag/PbBiO2Br composites were employed for the degradation of rhodamine B (RhB) and antibiotic bisphenol A (BPA) under visible light irradiation. Results showed that the obtained AgBr/Ag-3/PbBiO2Br displayed optimal photocatalytic performance, which could remove almost all RhB within 25 min and effectively decompose 82.3% of BPA in 120 min. Three-dimensional excitation-emission matrix fluorescence spectra (3D EEMs) were utilized for the purposes of fully grasping the behaviors of RhB molecules during the reaction process. Meanwhile, the effects of initial RhB concentration and co-existent electrolytes were investigated from the viewpoint of practical application. In addition, there was no obvious loss in degradation efficiency even after four cycles. The enhanced photocatalytic performances of AgBr/Ag/PbBiO2Br 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 played a significant role in preventing AgBr from being further photocorroded, resulting in the formation of a stable Z-scheme photocatalyst system. This study demonstrated that using metallic Ag as an electron mediator to construct Z-scheme photocatalytic system provided a feasible strategy in promoting the stability of Ag-based semiconductors.