Photocatalytic Antibacterial Activity Research Articles

Highly flexible carbon nitride-polyethylene glycol-cellulose acetate film with photocatalytic antibacterial activity for fruit preservation

Cellulose acetate film, as a biodegradable and biomass-derived material, has great potential applications in food packaging. However, the poor mechanical and antibacterial properties limit its applications. Herein, a highly flexible carbon nitride-polyethylene glycol-cellulose acetate (CN-PEG-CA) film was successfully prepared by combining graphitic carbon nitride (g-C3N4) photocatalyst with cellulose acetate (CA). The g-C3N4 enables the film with antibacterial activity, as a green photocatalyst. PEG softens the rigid polymer CA and crosslinks CA, PEG, and g-C3N4 together by hydrogen bonding, as a flexible crosslinker. X-ray diffractometer (XRD), scanning electron microscope (SEM), and Fourier transform infrared spectrum (FT-IR) characterizations confirmed the successful preparation of the CN-PEG-CA film. The mechanical property tests demonstrated that adding PEG increased the elongation at break of the film by about 4 times. The composite film had high antibacterial activity, and the bactericidal rates on Escherichia coli and Staphylococcus aureus were 99.98 % and 99.89 %, respectively. It effectively extended the shelf life of strawberries to 96 h and effectively maintained the quality of strawberries during storage. After 96 h, the weight loss rate of strawberries packaged with 15 % CN-PEG-CA film was 21.83 %, vitamin C content was 45.47 %, titratable acidity content was 0.89 %, and color, hardness and total soluble solids were well maintained. And biocompatibility test results showed that the film was safe and nontoxic. From the ecological and economic point of view, the highly flexible and biodegradable films with efficient photocatalytic antibacterial activity synthesized in this paper have great potential in the field of food packaging.

Defect engineering of Cu2-xGaxO/PDINH nanomaterial for significantly improved photocatalytic antibacterial activities

The judicious engineering of defects and microstructure in novel photocatalysts is essential for optimizing their functional properties. This study focuses on the design of copper oxide (Cu2O)-based catalysts employing defect engineering and heterogeneous composition with perylene-3,4,9,10-tetracarboximide (PDINH) to enhance their photocatalytic antibacterial performance. Introducing transition metals such as gallium (Ga) into the Cu2O lattice serves to 1) generate Cu vacancies to accelerate reactive oxygen species (ROS) kinetics, 2) induce a small size effect in Cu2O nanoparticles to amplify photocatalytic activities, and 3) fine-tune electronic characteristics by modulating the electron density near the Fermi level and the d-band center. The defect engineering of doped Ga atoms and the p-n junction construction with PDINH resulted in a notable redshift of the light absorption edge of Cu2O. The optimized Cu2-xGaxO/PDINH (x=0.2) nanomaterials displayed superior photocatalytic antibacterial performance, achieving bacterial inhibition rates greater than 91% against Staphylococcus aureus and Pseudomonas aeruginosa. The nanomaterial also exhibited a large double-layer capacitance, elevated photocurrent density, and substantial ROS production. Cu1.8Ga0.2O/PDINH nanomaterial was a potent candidate for photocatalysis and environmentally friendly antibacterial treatments.

Photocatalytic Zinc Oxide Nanoparticles in Antibacterial Ultrafiltration Membranes for Biofouling Control.

Global water scarcity is a threat that can be alleviated through membrane filtration technologies. However, the widespread adoption of membranes faces significant challenges, primarily due to membrane biofouling. This is the reason why membrane modifications have been under increasing investigation to address the fouling issues. Antibacterial membranes, designed to combat biofouling by eliminating microorganisms, offer a promising solution. Within this study, flat sheet ultrafiltration (UF) membranes with integrated photocatalytic zinc oxide (ZnO) nanoparticles were developed, characterized, and assessed through filtration and fouling tests. The antibacterial properties of the membranes were conducted in static tests using Gram-negative bacteria-Escherichia coli-and natural tap water biofilm. The results demonstrated a notable enhancement in membrane surface wettability and fouling resistance. Furthermore, the incorporation of ZnO resulted in substantial photocatalytic antibacterial activity, inactivating over 99.9% of cultivable E. coli. The antibacterial activity persisted even in the absence of light. At the same time, the persistence of natural tap water organisms in biofilms of modified membranes necessitates further in-depth research on complex biofilm interactions with such membranes.

Nickel-doped microtubular CeVO4 inspired by wood powder structure for visible light photocatalytic degradation of methylene blue and bacterial inactivation

In this study, inspired by natural wood powder structure, nickel-doped microtubular cerium vanadate (Ni/T-CeVO4) was obtained using wood powder as a biological template. Photocatalytic experiments under visible light revealed that Ni/T-CeVO4-3wt possessed the highest photocatalytic activity, with a degradation efficiency of up to 99 % for methylene blue. The enhanced photocatalytic performance was not only attributed to the microtubule wood powder structure assigned the composite a larger specific surface area but also the nickel doping narrowed the band gap of the composites while introducing more oxygen vacancies. The rapidly generated current in transient photocurrent responses and small arc radius in electrochemical impedance spectra further indicated the higher photogenerated carrier separation and smaller photogenerated electron transfer resistance within the composite. ESR spin-trapping tests proved that O2− and OH dominated the photocatalytic process. Furthermore, owing to its unique structural characteristics, the composite showed excellent photocatalytic antibacterial activity against Staphylococcus aureus and Escherichia coli. The present study provides a theoretical basis for developing efficient dual-effect photocatalysts using visible light to remove organic dyes and pathogenic bacteria from the water environment.

Construction of a g-C3N4/Bi(OH)3 Heterojunction for the Enhancement of Visible Light Photocatalytic Antibacterial Activity.

Photocatalytic technology has been recently conducted to remove microbial contamination due to its unique features of nontoxic by-products, low cost, negligible microbial resistance and broad-spectrum elimination capacity. Herein, a novel two dimensional (2D) g-C3N4/Bi(OH)3 (CNB) heterojunction was fabricated byincorporating Bi(OH)3 (BOH) nanoparticles with g-C3N4 (CN) nanosheets. This CNB heterojunction exhibited high photocatalytic antibacterial efficiency (99.3%) against Escherichia coli (E. coli) under visible light irradiation, which was 4.3 and 3.4 times that of BOH (23.0%) and CN (28.0%), respectively. The increase in specific surface area, ultra-thin layered structure, construction of a heterojunction and enhancement of visible light absorption were conducive to facilitating the separation and transfer of photoinduced charge carriers. Live/dead cell staining, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) assays and scanning electron microscopy (SEM) have been implemented to investigate the damage to the cell membrane and the leakage of the intracellular protein in the photocatalytic antibacterial process. The e-, h+ and O2•- were the active species involved in this process. This study proposed an appropriate photocatalyst for efficient treatment of bacterial contamination.

Enhanced photocatalytic antibacterial activity of Au-coated Ni–Ti–O nanotubes for biomedical applications

Nickel-titanium (NiTi) alloy is a smart material exhibiting superelasticity, contributing to low stiffness and facilitating integration with bone structures. However, NiTi alloy's bioactivity and antibacterial activity limit its dental applications. In this study, we fabricated nickel titanium oxide (Ni–Ti–O) nanotubes with the potential for bioactivity and photocatalytic properties on the surface of NiTi alloy. Specifically, we applied a coating of gold (Au) nanoparticles to the surface of Ni–Ti–O nanotubes, in order to leverage the antibacterial activity through the photocatalytic effect under 470 nm visible light. Field-emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) observations revealed that Au was deposited mainly at the top surface of Ni–Ti–O nanotubes (diameter: 12.76 ± 2.91 nm, height: 721.12 ± 50.25 nm). X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectroscopy (DRS) analyses revealed that the Ni–Ti–O nanotubes were NiTiO3 crystalline phases with low crystallinity. Therefore, based on the methylene blue (MB) degradation test, the photocatalytic effect was only achieved under visible light at 470 nm, facilitated by the presence of Au. The antibacterial colony forming unit test and enzymatic activity tests demonstrated that Au-coated Ni–Ti–O nanotubes displayed excellent antibacterial activity under 470 nm visible light irradiation, which was also attributed to photocatalytic effect. Consequently, the combination of Au-coated Ni–Ti–O nanotubes and visible light-based photofunctionalization holds promise for expressing antibacterial properties in dental applications.

AgNPs/g-C3N4/PVA antibacterial hydrogel with excellent photocatalytic antibacterial activity for wound dressing

AgNPs/g-C3N4/PVA hydrogel has been prepared by cyclic freeze-thaw method. E. coli was used as the model microbe and full-thickness wound defect models in mice were established to assess the antimicrobial activity of the hydrogel in vitro and in vivo.

Highly hydrophilic and dispersed TiO2 nano-system with enhanced photocatalytic antibacterial activities and accelerated tissue regeneration under visible light

Titanium dioxide (TiO2)-based photodynamic antibacterial (PDA) agents present a novel approach for addressing drug-resistant bacterial infections and the associated tissue damage. However, the suboptimal dispersibility, negative charge, and weak photocatalytic activity under visible light of TiO2 hinder its practical applications. This study aimed to address these limitations by developing a highly hydrophilic and dispersed Zn-TiO2/reduced graphene oxide (rGO) (HTGZ) nano-system with exceptional visible light catalytic activity and tissue repair ability. HTGZ produced an antibacterial ratio over 98% within a short time, likely due to the enhanced production of reactive oxygen species under visible light. After being co-cultured for 4 days, L929 cells and BMSCs maintained over 90% activity, indicating that HTGZ had no significant cytotoxicity. Furthermore, the transcriptomic and metabolic analyses revealed that the antibacterial mechanism mainly came from the destruction of cell membranes and the disruption of various metabolic processes, such as purine metabolism and fatty acid biosynthesis. Critically, results of in vivo experiments had authenticated that HTGZ significantly promoted infected tissue regeneration by slaughtering bacteria and release Zn2+. After 14 days, the wound area was only one-third that of the control group. Overall, the enhanced antibacterial efficacy and wound-healing potential position HTGZ as a promising nano-antibacterial medication for the clinical treatment of infectious bacterial diseases.

Visible-light-driven Au/PCN-224/Cu(II) modified fabric with enhanced photocatalytic antibacterial and degradation activity and mechanism insight

The development of novel photocatalytic platform for efficient water purification and sterilization is of utmost importance due to the significant threat of chronic diseases resulting from water pollution and bacterial contamination. Herein, a high-efficiency, easy-recyclable, and environment-friendly photocatalytic fabric was developed as a water disinfection and organic pollutant degradation platform. In which, microamounts of Au nanoparticles (2 wt%) and Cu(II) clusters (2.5 wt%) co-decorated porphyrinic MOF (Au/PCN-224/Cu(II)) coating was applied as photocatalytic surface, and flexible cotton fabric served as stable support. Au/PCN-224/Cu(II) composite photocatalyst was prepared via a facile photo-deposition procedure followed by impregnation method, and further immobilized onto polydopamine (PDA) pre-treated cotton fabric through catechol-amine reaction. The fabricated photocatalytic platform exhibited excellent ability to generate reactive oxygen species (ROS) by multiple routes under low-power visible light irradiation, and achieved efficient photodisinfection effects for causative organism including Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) without the obvious leakage of metal ions from the potocatalyst during the reaction. Additionally, the reaction rate constant for organic dye MB photodegradation achieved by Au/PCN-224/Cu(II)@Fabric was 3.73 times higher than that of PCN-224@Fabric, and the degradation intermediates analysis was also conducted. The band alignments of PCN-224, Au/PCN-224, Au/PCN-224/Cu(II) photocatalysts were determined, and the charge transfer mechanism within Au/PCN-224/Cu(II) photocatalyst was elucidated through the utilization of DRS, Mott − Schottky, ESR, EIS, and photocurrent analyses. It is suggested that the deposition of Au and doping of Cu(II) both with small amounts enhanced the light absorption capacity, and also improved the charge separation ability through the surface plasmon resonance (SPR) effect and interfacial electron transfer (IFCT) mechanism. Moreover, Au SPR and Cu doping exhibited a substantial enhancement in photothermal conversion effect, thereby synergistically reinforcing the sterilization performance. This work provides an approach for the development of effective photocatalytic platform based on porphyrinic MOFs combined with trace metal co-catalysts in the application of water disinfection and purification.

Photo-crosslinked composite hydrogels with silver-deposited polymeric carbon nitride for boosting antibacterial activity

Rational design of antibacterial hydrogels is an important link to promote the multi-scenario application of this promising soft material. Herein, acrylamide and sodium alginate were selected as mixed monomers, silver-deposited polymeric carbon nitride nanosheets were used as a photoinitiator, pre-gelation was achieved under UV irradiation, and then a composite hydrogel was obtained through calcium ion crosslinking. The composite hydrogels exhibit good mechanical stability, structural stability in water and degradability under simulated physiological conditions. The composite hydrogels have the activity of killing Escherichia coli with or without light. The visible light response and surface plasmon resonance effect of the silver-deposited polymeric carbon nitride boosted the photocatalytic antibacterial activity of the composite hydrogels, and the bactericidal rate of the optimal sample reached 95.5% after 120 min of visible light irradiation. This work provides a constructive and green roadmap for the design of composite dual-network photoresponsive antibacterial hydrogels.

Study of bismuth metal organic skeleton composites with photocatalytic antibacterial activity

A composite based on Ag and carbon quantum dot (CQDs) doped bismuth metal organic framework (CAU-17) was synthesized by a one-step thermal solvent in situ growth. The microstructure, chemical composition, morphology, photogenerated electron-hole pairs, and photocatalytic activity of the composite were characterized. The produced composite with its unique energy band structure, enhances the visible light absorption and effectively delays the recombination of the photogenerated carriers. On the other hand, the modification with CQDs increases the concentration and transport rate of photogenerated carriers mainly attributed to their superior electron transport capacity and light trapping ability. The photocatalytic antibacterial effect of CAU-17/Ag/CQDs against common Gram-positive, Gram-negative bacteria (Staphylococcus aureus, Escherichia coli) and drug-resistant bacteria (methicillin-resistant Staphylococcus aureus), as well as its inhibition against HepG2 tumor cell were investigated. The results showed that CAU-17/Ag/CQDs exhibited a photocatalytic antibacterial effect with an inactivation rate as high as 99.9 %. At the low dose (0.2 mg/mL), CAU-17/Ag/CQDs indicated a significant inhibition against bacterial growth 20 min after visible light exposure, whereas at the concentration of 0.5 mg/mL, CAU-17/Ag/CQDs completely killed all the tested bacteria. At the concentration of 0.8 mg/mL, the inhibition rate against HepG2 tumor cells reached 75 %. The excellent photocatalytic property of the as prepared composite contributed to the doping of Ag and CQDs, which fundamentally altered the morphology and energy band distribution. Such a composite can be developed into an effective photocatalytic disinfection system and applied to water purification systems, biofilm rejection, combating different antibiotic resistances, and tumor therapy.

Augmenting reactive species over MgIn2S4-In2O3 hybrid nanofibers for efficient photocatalytic antibacterial activity

Narrow bandgap semiconductor MgIn2S4 has been readily grown onto In2O3 nanofibers by an in situ growing method. The so-formed MgIn2S4-In2O3 hybrid nanofibers are characterized by strong visible light absorption and intimate MgIn2S4/In2O3 heterointerfaces. Under visible light illumination (λ ≥ 400 nm), the hybrid nanofibers demonstrate an exceptionally high photocatalytic activity for Escherichia coli (E. coli) disinfection, outcompeting pristine MgIn2S4, naked In2O3 nanofibers, and many other photocatalytic systems reported. Specifically, the hybrid nanofibers achieve a 7 log reduction in viable cells for merely 20 min illumination while pristine MgIn2S4 and naked In2O3 nanofibers alone are almost inactive. Further analysis indicates that the hybrid nanofibers essentially form a type-II semiconductor heterojunctions which enable spatial separation of photocarriers. Owing to the intimate heterointerfaces, photocarriers can be promptly separated and accumulated respectively in In2O3 and MgIn2S4 thereby allowing continuous generation of copious reactive species for disinfection. This work signifies the usefulness of heterointerfaces in promoting photocarrier separation and provides a useful strategy to upgrade photocatalytic performance from otherwise almost inactive semiconductors.

Quantitative generation of ROS and their effective photocatalytic antibacterial activity of high-intensity universal P25 network films: The role of ROS

Reactive oxygen species (ROS) generation and utilization were the foundation for the photocatalytic degradation of pollutants or anti-bactericidal effect. Especially for solid-phase film photocatalysis, a simple and firm immobilization method that ensured exposure of active sites and effective production of ROS was the key. Presently, a P25 network films was achieved using water-based polyurethane acrylate (WPUA) as adhesive through a simple and convenient direct spraying method. The physical and chemical properties of the P25 network films were characterized and the results showed that P25 was firmly adhered on the metal wire mesh and fully exposed the active sites of P25. Dynamic generation of ROS on 304SS@P25 films interface was systematically investigated. The concentration of hydroxyl radicals (•OH), superoxide radicals (O2•−) and hydrogen peroxide (H2O2) on 10 cm × 3 cm 304SS@P25 after 2 h of UV irradiation were 9.4 ± 0.3 × 10−9 M, 7.6 ± 0.3 × 10−9 M, and 11.7 ± 0.9 × 10−6 M, respectively, which was similar with ROS generation of P25 nanoparticle suspensions. In addition, the ROS-mediated antibacterial effect of 304SS@P25 films was investigated, and a linear correlation was found between the concentration of ROS generated and the E. coli sterilization rate. Furthermore, 304SS@P25 films could be successfully applied in the air sterilizer to exhibit a good bactericidal effect. This ROS-oriented photocatalyst immobilization method opened up a new pathway for water and air purification and provided a new strategy in the field of photocatalytic antibacterial technology.

Antibacterial activity of SnO2 in visible light enhanced by erbium–cobalt co-doping

In this work, a series of SnO2 samples with systematically varied doping amounts of Er and Co were prepared via a precipitation–hydrothermal method. The results show that after Er doping, the 4I15/2 ground state of Er3+ jumps to the 4H11/2 higher-energy level, and the Er-doped SnO2 samples can efficiently convert low-energy light into high-energy light. Thus, Er doping is beneficial for improving the visible and near-infrared light response of SnO2 and thus enhances its photocatalytic performance. Furthermore, doping SnO2 with Co leads to a distortion of the SnO2 lattice. A proportion of the SnO2 lattice is replaced by Co atoms, which can effectively lower the bandgap of SnO2, widen its optical response range, and enhance its sunlight absorption efficiency. The photocatalytic antibacterial activities of pure SnO2, as well as SnO2 co-doped with Er and Co in visible light, were investigated under visible light using Escherichia coli. SnO2 shows the best antibacterial activity and electron–hole separation efficiency when co-doped with 1.5 mol. % Er and 1.5 mol. % Co (Er1.5Co1.5-SnO2). Gradient experiments reveal that mainly the reactive oxygen species affect the antibacterial activity of pure SnO2. The improved antibacterial performance of Er1.5Co1.5-SnO2 is attributed to the increased generation of·O2− and·OH. In addition, scavenger experiments reveal that·O2− is the key contributor to the enhanced antibacterial activity of SnO2.

Standardized Figures of Merit for Proper Benchmarking of Photocatalytic Inactivation of Bacteria Using Thin Films Based on TiO2 Nanostructures.

The study of photocatalysts fixed to surfaces for the inactivation of bacteria in wastewater has increased in recent years. However, there are no standardized methods to analyze the photocatalytic antibacterial activity of these materials, and no systematic studies have attempted to relate this activity to the number of reactive oxygen species generated during UV-light irradiation. Additionally, studies regarding photocatalytic antibacterial activity are usually carried out with varying pathogen concentrations, UV light doses, and catalyst amounts, making it difficult to compare results across different materials. The work introduces the photocatalytic bacteria inactivation efficiency (PBIE) and bacteria inactivation potential of hydroxyl radicals (BIPHR) figures of merit for evaluating the photocatalytic activity of catalysts fixed onto surfaces for bacteria inactivation. To demonstrate their applicability, these parameters are calculated for various photocatalytic TiO2 -based coatings, accounting for the catalyst area, the kinetic reaction rate constant associated with bacteria inactivation and hydroxyl radical formation, reactor volume, and UV light dose. This approach enables a comprehensive comparison of photocatalytic films prepared by different fabrication techniques and evaluated under diverse experimental conditions, with potential applications in the design of fixed-bed reactors.

Zinc porphyrin covalent organic nanodisks synthesized from covalent organic frameworks and their photocatalytic antibacterial activity

Zinc porphyrin covalent organic nanodisks synthesized from covalent organic frameworks and their photocatalytic antibacterial activity

Fluorescence turn off-on detection of Co2+ and enrofloxacin by N, Cl-carbon dots prepared in deep eutectic solvent and study of their photocatalytic antibacterial activity

Nitrogen, chloride doped carbon dots (N, Cl-CDs) were synthesized in deep eutectic solvent. TEM, XRD, FT-IR, XPS, EDAX, UV–Vis and fluorescence were used for characterization. Quantum yield and average size of N, Cl-CDs were 38.75 % and 2–3 nm, respectively. N, Cl-CDs fluorescence was turn off by cobalt ion and then turn on gradually after addition of enrofloxacin. Linear dynamic range and detection limit (DL) for Co2+ and enrofloxacin were (0.1–70 µM and 30 nM) and (0.05–50 µM and 25 nM), respectively. Enrofloxacin was detected in blood serum and water samples with the recovery of 96–103 %. Finally, Antibacterial activity of the carbon dots was also investigated.

Liquid exfoliation of bulk g-C3N5 to nanosheets for improved photocatalytic antibacterial activity.

Liquid exfoliation of bulk g-C3N5 was applied to synthesize g-C3N5 nanosheets. In order to characterize the samples, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), X-ray photoelectron spectra (XPS), UV-Vis absorption spectra (UV-Vis), and photoluminescence spectra (PL) were examined. g-C3N5 nanosheets exhibited enhanced performance in the inactivation of Escherichia coli (E. coli) with visible light irradiation relative to bulk g-C3N5 and promoted complete inactivation of E. coli within 120 min. h+ and •O2- were the principal reactive species in the antibacterial process. In the early stages, SOD and CAT played a defensive role in resisting oxidative damage of active species. With the prolonged light exposure time, the antioxidant protection system was overwhelmed leading to the destruction of the cell membrane. The leakage of cell contents such as K+, protein, and DNA caused bacterial apoptosis ultimately. The enhanced photocatalytic antibacterial performance of g-C3N5 nanosheets is ascribed to the stronger redox property by the upward shift of CB and downward shift of VB compared with bulk g-C3N5. On the other hand, larger specific surface area and better separation efficiency of photoinduced carriers are helpful to the improved photocatalytic performance. This study systematically revealed the inactivation process toward E. coli and expanded the application range of g-C3N5-based materials with abundant solar energy.

Microemulsion–Assisted Synthesis of Ag2CrO4@MIL–125(Ti)–NH2 Z–Scheme Heterojunction for Visible–Light Photocatalytic Inactivation of Bacteria

Metal–organic frameworks (MOFs) are new porous materials composed of metal centers and organic ligand bridges, which received great attention in the field of photocatalysis. In this work, Ag2CrO4@MIL–125(Ti)–NH2 (denoted as AgCr@M125) Z–scheme heterojunctions were synthesized via a simple microemulsion method, by which highly dispersed nano–sized Ag2CrO4 can be anchored uniformly on the surfaces of porous MIL–125(Ti)–NH2 (denoted as M125). Compared with pure M125 and Ag2CrO4, the as–prepared AgCr@M125 hybrids show significant photocatalytic efficiency against inactivated Staphylococcus aureus (S. aureus), reaching over 97% inactivation of the bacteria after 15 min of visible light irradiation. Notably, the photocatalytic activity of the obtained 20%AgCr@M125 is about 1.75 times higher than that of AgCr–M125, which was prepared via a traditional precipitation method. The enhanced photocatalytic antibacterial activity of the AgCr@M125 photocatalytic system is strongly ascribed to a direct Z–scheme mechanism, which can be carefully discussed based on energy band positions and time–dependent electron spin response (ESR) experiments. Our work highlights a simple way to enhance the antibacterial effect by coupling with Ag2CrO4 and M125 via a microemulsion–assisted strategy and affords an ideal example for developing MOFs–based Z–scheme photocatalysts with excellent photoactivity.

Ag@Bi5O7I nanoparticles deposited on Bi(OH)3 nanosheets for boosting photocatalytic antibacterial activity under visible light irradiation

A novel Ag@Bi5O7I/Bi(OH)3 (AB) heterojunction was prepared and the enhanced photocatalytic antibacterial activity against Escherichia coli (E. coli) under visible light excitation was exhibited. 3 %AB (containing 3 wt% of Ag) presented best photocatalytic performance, and all of E. coli cells were inactivated within 5 min under natural solar light irradiation. The photocatalytic antibacterial mechanism of AB heterojunction was corroborated by SEM, live/dead cell staining and SDS-PAGE assay. The destruction of the cell membrane, the leakage of the intracellular protein and the decomposition of the protein were considered as the events occurred in the antibacterial process. The radical capture experiment confirmed that •O2– and e– played the dominant role in the destruction of the cell membrane and the decomposition of the protein. The improvement of the photocatalytic activity can be mainly ascribe to the construction of heterojunction, SPR effect resulted from Ag deposition, enhanced visible light absorption and more surface oxygen vacancies. These factors are advantageous to the generation of the photogenerated electrons and holes, and improve the spatial separation efficiency of the photogenerated charge. This study presented a promising Ag@Bi5O7I/Bi(OH)3 heterojunction as the photocatalyst for the potential application in the treatment of the bacterial contamination.