Photocatalytic Disinfection Research Articles

Elucidating antibiofilm as well as photocatalytic disinfection potential of green synthesized nanosilver against multi-drug-resistant bacteria and its photodegradation ability of cationic dyes

BackgroundBioinspired nanomaterials have widely been employed as suitable alternatives for controlling biofilm and pathogens due to their distinctive physico-chemical properties.MethodologyThis study explored the antibiofilm as well as photocatalytic potential of silver (Ag) nanoparticles (NPs) synthesized using the cell-free supernatant of Lactobacillus acidophilus for the disinfection of multi-drug-resistant (MDR) strains of enteroaggregative E. coli (EAEC), Salmonella Typhimurium, S. Enteritidis and methicillin-resistant Staphylococcus aureus (MRSA) on exposure to LED light. In addition, the removal of toxic cationic dyes i.e., methylene blue (MB), rhodamine B (RhB) and crystal violet (CV) was explored on exposure to sunlight, LED and UV lights.ResultsInitially, the synthesis of AgNPs was verified using UV- Vis spectroscopy, X-ray diffraction and transmission electron microscopy. The synthesized AgNPs exhibited MIC and MBC values of 7.80 and 15.625 µg/mL, respectively. The AgNPs exhibited significant inhibition (P < 0.001) in the biofilm-forming ability of all the tested MDR isolates. On exposure to LED light, the AgNPs could effectively eliminate all the tested MDR isolates in a dose-dependent manner. While performing photocatalytic assays, the degradation of RhB was observed to be quite slower than MB and CV irrespective of the tested light sources. Moreover, the sunlight as well as UV light exhibited better photodegradation capacity than LED light. Notwithstanding the light sources, RhB followed zero-order kinetics; however, MB and CV followed primarily second-order kinetics.ConclusionThe green synthesized AgNPs were found to be an effective photocatalytic as well as antifouling candidate that could be applied in therapeutics and wastewater treatment.

Low oxygen adsorption energy barrier architectures to facilitate microenvironmental photocatalytic disinfection in Wei River

Photocatalytic disinfection is an eco-friendly strategy that uses solar energy to purify bacteria-contaminated water. However, improvements in photocatalysts tend to focus on thermodynamics while neglecting kinetic interactions that involve oxygen. Here, we propose the MOF-on-MOF heterojunction NR-HKUST-1@Cu/ZIF-8 (NH@CZ) for kinetic photocatalytic disinfection; the heterojunction reduced bacterial load by nearly 8-log within 20 min. The NH@CZ structure exhibits a high specific surface area with Cu2O8 and CuN4 sites that provide substantial oxygen storage capacity and binding sites. In vitro experiments demonstrated the effective delivery of oxygen to photocatalytic reactions via NH@CZ, leading to enhanced superoxide radical (·O2-) generation. Experimental analysis and theoretical calculations confirm that the formation of heterojunctions in NH@CZ provides an efficient pathway for oxygen reduction by reducing the energy barrier associated with oxygen adsorption. Mechanistic studies show that reactive oxygen species (ROS) disrupt bacterial cell membranes, resulting in the release of cellular contents (e.g., potassium ions and macromolecular proteins) and subsequent cell death. Furthermore, the oxygen-carrying NH@CZ killed all microorganisms in Wei River water samples within 45 min. The MOF-on-MOF heterojunction offers a promising pathway to enhance ROS generation and provides valuable insights into advances in water disinfection technology.

Positively charged 3-D interface mediated electrostatic adsorption of microorganisms for enhanced photocatalytic disinfection

Photocatalysis offers a sustainable method for disinfecting natural drinking water. However, the photoactive species generated at the catalyst interface face challenges in migrating over long distances in water to interact with bacteria. In this study, we introduce an enhanced photocatalytic disinfection strategy involves the in-situ growth of fluorine-modified titanium dioxide heterostructure arrays on carbon fibers. This method results in a positively charged photocatalytic fabric that effectively attracts negatively charged microbes to its surface, significantly reducing the mass-transfer distance of active species. The heterophase junction between rutile nanorods and anatase nanoparticles enhances charge separation efficiency, while fluorine doping in anatase nanoparticles creates a positively charged 3-D interface conducive to electrostatic adsorption and in-situ oxidation of microorganisms. When tested in actual rainwater, this photocatalytic fabric successfully reduced the bacterial count from 4500 CFU/mL to below the WHO drinking water standard of 100 CFU/mL over three cycles in a single day under natural sunlight.

CuO/ZnO heterojunction nanofilm for effective photocatalytic disinfection

Pathogenic bacteria can spread rapidly from contaminated surfaces to human skin once humans touch such surfaces, resulting in contact infection and subsequent bacterial infectious diseases. In addition to the bacterial drug resistance induced by overuse of antibiotics, the commonly used antibiotic bacteria-killing strategy is unsuitable for surface sterilization of facilities. Herein, a heterojunction CuO/ZnO nanofilm was constructed on glass plates by calcination and atomic layer deposition. This film exhibited excellent photocatalytic antibacterial activity under visible light. The heterostructure between CuO and ZnO at the interface accelerated the separation of photogenerated electrons and holes, resulting in increased yield of reactive oxygen species, which effectively kill bacteria. After 5 min of simulated sunlight irradiation, the antibacterial efficiencies of CuO/ZnO against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) were 99.68 ± 0.31 % and 96.49 ± 0.78 %, respectively. The photocatalytic antimicrobial nanofilm synthesized in this study can potentially be used for rapid and safe disinfection of contact surfaces in public facilities.

Amino acid-mediated chiral Ag@Au with circularly polarized light induced photothermal and photodynamic synergistic photocatalytic disinfection

As the deterioration of the environment, microbiological contamination of drinking water is threatening human health. Therefore, it is crucial to investigate rapid, reliable, and safe sterilization techniques. In this study, chiral Ag@Au nanoparticles (L/D-NPs) were synthesized using an amino acid-mediated protocol. The L/D-NPs demonstrated outstanding photothermal and photodynamic capabilities when irradiated with linearly polarized (LP) light. The photothermal and photodynamic synergism demonstrated by L/D-NPs resulted in high sterilization capability against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). It was noteworthy that these results were chirality-independent. With the interaction of chirality-matched circularly polarized light (CPL) and chiral NPs, excellent sterilization performance could be achieved even at a much lower concentration. The mechanisms were investigated using Finite-Difference Time-Domain (FDTD) simulations and photocurrent-time measurements. In addition, under identical conditions, chiral NPs were found to maintain excellent sterilization performance for the complex microbial system of actual river water. This work offers novel guidance and insights into photocatalytic disinfection, including sterilization of water and public facilities.

Sandwich-structured continuous ZIF-8/Ti3C2 MXene/ZIF-8 for efficient sterilization: Enhanced photocatalytic activity, photothermal effect, and environmental safety

The development of effective water purification systems is crucial for controlling and remediating environmental pollution, especially in terms of sterilization. Herein, we demonstrate elaborately designed composite nanosheets with a sandwich structure, composed of two-dimensional (2D) Ti3C2 MXene nanosheet core and conformal ZIF-8 ultrathin outer layers, and their potential applications in photocatalytic sterilization. The study results indicate that the conformal ZIF-8-MXene nanosheet exhibits an expanded light absorption range (826 nm), improved photothermal conversion efficiency (6.2 °C s−1), and photocurrent response, thus boosting photocatalytic sterilization efficiency (6.63 log10 CFU mL−1) against Escherichia coli under simulated sunlight within 90 min. Interestingly, 2D ZIF-8 layers exhibit positive zeta potential (19 mV), good hydrophilicity (40.6°), and local photogenerated-hole accumulation, possessing efficient bacteria-trapping efficiency. Membrane filters fabricated from optimized composite nanosheets exhibit an outstanding bacteria-trapping and sterilization efficiency (almost 100 %) against Escherichia coli under simulated sunlight within 30 min of the flow photocatalytic experiments. This work not only presents a rational structural design of the conformal and ultrathin anchoring of ZIF-8 onto a 2D conductive material for bacteria-trapping and sterilization, but also opens new opportunities for using metal–organic frameworks in photocatalytic disinfection of drinking water.

Coupled capture and photocatalysis of g-C3N4 based magnetic composites: Mechanism and disinfection activity against Staphylococcus aureus

The disinfection ability of g-C3N4 by photocatalysis is restricted, owing to its small surface area and rapid combination of holes (h+) and electrons (e−). Moreover, recycling of g-C3N4-based photocatalysts from aqueous solution is difficult, which increases the cost of application. In the present study, g-C3N4 was combined with magnetic biochar (MBC) by high temperature calcination to fabricate g-C3N4/MBC composites. The as-prepared g-C3N4/MBC composites acquired larger specific surface area, narrow bandgap, and broad-range of visible absorption capability. The g-C3N4/MBC composites showed good killing efficiency towards Staphylococcus aureus (S. aureus) under visible light irradiation. Efficient photocatalysis was achieved by the effective separation of e−/h+ within the g-C3N4/MBC composites. Moreover, the capture effect of MBC for S. aureus reduced the distance and increased the contact area between the g-C3N4/MBC composite and S. aureus. The g-C3N4/MBC-10 % showed notable stability and reusability over a broad pH range of 4–8 and in presence of different inorganic ions (Cl− and SO42−) and humic acid. After 5 cycles, the g-C3N4/MBC-10 % could still eliminate about 95 % of S. aureus cells. The g-C3N4/MBC-10 % was also highly effective in reducing the bacterial population in water samples taken from a nearby lake, thus showing considerable promise for use in water sterilization. In addition, g-C3N4/MBC composites were highly effective in eliminating the biofilm and inhibiting the growth of the new biofilm of S. aureus. The main active species in photocatalytic disinfection were determined, to be •OH, h+, and •O2−. This study would help to understand the capture and photocatalysis of g-C3N4 based composites for environmental applications.

Multifunctional BiOBr/BiOI 3D microspheres for improving visible-light-driven photocatalytic degradation and disinfection efficiency

The antibiotic abusing has triggered serious wastewater pollution and bacterial resistance that leads to much burden to human health. In this work, BiOBr/BiOI dimensional (3D) nanoarchitectures were synthesized using solvothermal method by adjusting the molar ratio of Br/I, and 56%BiOBr/BiOI exhibited the best photocatalytic activities on Tetracycline (TC) degradation and disinfection toward Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) under visible light (λ > 420 nm). The optimized photodegradation efficiency of TC was up to 66.4%, and the corresponding E. coli and S. aureus survival rates were estimated as 4.9% and 22.6%, respectively. The photocatalytic mechanism indicated that the reactive oxygen species (ROS) (especially for •O2-) play an important role in the inactivation of bacteria and the photodegradation process. For the first time, the in vivo experiments were conducted to reveal the highly effective sterilization performance of BiOBr/BiOI in promoting the skin wound healing under visible light. This study informed that BiOBr/BiOI composite might be a promising photocatalyst dealing with antibiotic and bacteria in wastewater.

Enhancing the Production of Eco-Friendly Silk Fabrics through the Application of Nonthermal Plasma Wettability Techniques.

The combination of the effects of nonthermal plasma using atmospheric pressure of plasma jet and the photocatalytic effects of titanium dioxide nanoparticles was used to study the plasma flow modes, electrical characteristics, nonthermal characteristics, antimicrobial measurements, and surface modifications. Using different wettabilities of argon discharges in a laminar flow: (i) wet I, wettability with 2.4 slm argon mixture with oxygen ratio O2, equivalent to 15 mslm (Ar/O2), and (ii) wet II, wettability (Ar/O2) mixture combined with titanium dioxide, to accelerate the inactivation process on the nonwoven fabric surface. For wet 0, wet I, and wet II discharges, the average rate of heat transfer to the nonwoven silk fabric increased significantly. Specifically, it goes from 104.6 to 118.6 and then to 241.7 mW, respectively. The kinetic deactivation rate of Escherichia coli increases starting at 0.20, then going up to 0.32, and finally reaching 0.57 min-1. The increased wettability of the TiO2 photocatalyst results in an enhanced bactericidal rate, which is caused by both the heat impact from the nonthermal jet and potentially photocatalytic disinfection, leading to the generation of active species. The mechanical parameters owing to different wettabilities and plasma interactions with the fabric membrane were tested for the treated samples, such as stiffness, ultimate yield strength, tensile strength, strain, hardening, elongation, resilience, and toughness.

Strategic implementation of upflow microbubble airlift photocatalytic process to control heavy metal resistant-MDR bacteria and the associated genes in wastewater

The emergence of multidrug resistance (MDR) and heavy metal resistance (HMR) in bacterial pathogens and genes through mobile genetic elements (MGEs) from wastewater effluents needs to be eradicated using green technology. HMR is critical to controlling antimicrobial resistance but has been neglected in most photocatalytic disinfection (PCD) studies. Advanced photocatalysis in antimicrobial studies requires a strategic approach to enhance the disinfection efficiency. This study applied an optimized upflow airlift photocatalytic reactor (UAPR) with microbubble air and blue light to remove the antimicrobial resistance (HMR–MDR bacteria (HMR–MDRB), HMR genes (HMRGs), antibiotic resistant genes (ARGs) and MGEs) and inhibit pathogenicity in a mixed culture of high-strength HMR–MDRB isolated from wastewater. Stable dissolved oxygen (DO) supplementation and blue light significantly affected the HMRGs and MGE reduction, resulting in enhanced disinfection activity (30 %) and reaction time (60 min) required for the complete inactivation of HMR-MDRB mixed culture. The process effectively reduced the blaNDM-1 (3.37 log), pbrT (2.18 log), intl1 (2.16 log), and tn916/1545 (4.07 log), with a PCD rate constant (kg) of 0.0515 min−1, 0.0359 min−1, 0.0292 min−1, and 0.0662 min−1, respectively. Process mechanism studies showed that the stable supplementation of DO was a critical factor in controlling the type of reactive oxygen species (ROS), resulting in type II ROS, 1O2, as the critical free radical contributing to the reduction of ARGs and integron, whereas h+ was the ROS for pbrT and transposon.

A Robust Pyro-phototronic Route to Markedly Enhanced Photocatalytic Disinfection.

Photocatalysis offers a direct, yet robust, approach to eradicate pathogenic bacteria. However, the practical implementation of photocatalytic disinfection faces a significant challenge due to low-efficiency photogenerated carrier separation and transfer. Here, we present an effective approach to improve photocatalytic disinfection performance by exploiting the pyro-phototronic effect through a synergistic combination of pyroelectric properties and photocatalytic processes. A set of comprehensive studies reveals that the temperature fluctuation-induced pyroelectric field promotes photoexcited carrier separation and transfer and thus facilitates the generation of reactive oxygen species and ultimately enhances photocatalytic disinfection performance. It is worth highlighting that the constructed film demonstrated an exceptional antibacterial efficiency exceeding 95% against pathogenic bacteria under temperature fluctuations and light irradiation. Moreover, the versatile modulation role of the pyro-phototronic effect in boosting photocatalytic disinfection was corroborated. This work paves the way for improving photocatalytic disinfection efficiency by harnessing the synergistic potential of various inherent material properties.

Effect of humic acid on visible light photocatalytic inactivation of bacteriophage f2 with electrospinning Cu-TiO2 nanofibers: insight into the mechanisms.

Photocatalytic disinfection is a promising technology with low cost and high efficiency. However, most of the current studies on photocatalytic disinfection ignore the widespread presence of natural organic matter (NOM) in water bodies, so the incomplete conclusions obtained may not be applicable. Herein, this paper systematically studied the influence of humic acid (HA), one of the most important components of NOM, on the photocatalytic inactivation of bacteriophage f2 with electrospinning Cu-TiO2 nanofibers. We found that with the addition of HA, the light transmittance of the solution at 550 nm decreased from 94 to 60%, and the band gap of the photocatalyst was increased from 2.96 to 3.05 eV. Compared with reacting without HA, the degradation amount of RNA of f2 decreased by 88.7% after HA was added, and the RNA concentration increased from 1.95 to 4.38 ng·μL-1 after the reaction. Hence, we propose mechanisms of the effect of HA on photocatalytic disinfection: photo-shielding, passivation of photocatalysts, quenching of free radicals, and virus protection. Photo-shielding and photocatalyst passivation lead to the decrease of photocatalyst activity, and the reactive oxygen species (ROSs) (·OH, ·O2-, 1O2, H2O2) are further trapped by HA. The HA in water also can protect the shape of phage f2 and reduce the leakage of protein and the destruction of ribonucleic acid (RNA). This work provides an insight into the mechanisms for the influence of HA in photocatalytic disinfection process and a theoretical basis for its practical application.

Green graphene supported Cu2O-Ag2O S-scheme photocatalyst with high disinfection activity for prevention of urinary tract infection in toilets: A metagenomic analysis

Amongst the universal infectious diseases, the urinary tract infection (UTI) is one of the most prevalent bacterial infections. Pathogenic microorganisms causing UTI mainly enter the human body from the unhygienic toilet environment. In this study, a graphene structured material (GSM) supported Cu2O-Ag2O composite was synthesized using the co-precipitation method and its photocatalysis-assisted disinfection performance against UTI-causing pathogens was assessed under LED irradiation. The metagenomic analysis of UTI-causing sites was performed by targeting the 16 S rRNA gene region using Illumina sequencing. The results showed that the common phylum identified in the toilets under study is Proteobacteria (76%) and the most dominating genera identified were Acinetobacteria (33%) and Pseudomonas (26%). 8 × 106 CFU mL−1 of Acinetobacter baumanii, Pseudomonas aeruginosa, and Escherichia coli were completely disinfected using the GSM-Cu2O-Ag2O composite within 30 min under LED irradiation. Enterococcus faecalis and mixed bacterial culture took 40 and 75 min, respectively, for complete inactivation. Holes are the major reactive species responsible for photocatalytic inactivation of bacteria. The structural changes of the cells were observed using scanning electron microscopy which indicates that photocatalytic disinfection caused drastic damage to the bacterial cell walls and it was further substantiated by the measurements of DNA and K+ leakage. The composite displayed complete inactivation, remarkable stability and acceptable reusability even after four consecutive cycles. The green composite, after degradation, is supposed to get sequestered in the natural environment without any persistence and bio-magnification prospects. Its potential use can usher in a new greener alternative to traditional toxic disinfectants like benzalkonium chlorides that can exert adverse impacts on the biological environment including human health.

Enhanced inactivation of Staphylococcus aureus and Escherichia coli using conjugated polyindole polymer nanoparticles under visible light irradiation

AbstractThe areas of environmental cleanup and bacteria inactivation are particularly interesting in polymer‐based nanomaterials because of their unique physicochemical properties. Conjugated polymer nanoparticles (CP NPs) have potential uses in the biological and environmental, but little is known about them. This study aimed to examine the efficacy of CP nanoparticles in the photocatalytic inactivation of S. aureus and E. coli under visible irradiation (λ ≤ 420 nm), with minor enhancements observed. The simple and one‐step chemical oxidation technique was used to prepare CP nanoparticles. X‐ray powder diffraction (XRD), Fourier‐transform infrared spectroscopy (FT‐IR), Scanning electron microscope (SEM), Energy‐dispersive X‐ray (EDS), and Transmission electron microscopy (TEM) analyses were utilized to characterize the physicochemical properties of CP nanoparticles for comprehensive structural analysis. The synthesized CP nanoparticles exhibited outstanding photocatalytic disinfection capabilities, achieving a degradation of 98.6%. This research not only provides insights into the physical characteristics of CP nanoparticles but also illustrates their antibacterial efficacy against two different bacterial pathogens, namely S. aureus and E. coli. Therefore, this research highlights an eco‐friendly and inexpensive preparation of conjugated polymer nanoparticles for a wide range of applications.

Dynamic Ag-mediated electron transfer confined ZnO nanorods for boosted photocatalytic bacterial disinfection

Infectious diseases, particularly bacterial infections, pose a global crisis with significant impacts on public health and economic stability due to the emergence of multi-drug resistance and limitations in existing therapeutic options. The present study focused on the development of photocatalytic disinfectant and silver-decorated hexagonal zinc oxide nanorods (Ag/ZnO NRs) were fabricated through an ultrasonic-assisted solvothermal method, and investigated for the photocatalytic inactivation on E. coli. The morphological, structural, and optical characteristics of the fabricated Ag/ZnO NRs were systematically studied through various analytical techniques. Here, 3%Ag/ZnO NRs showed 96.9% inactivation of E. coli within 120 min of visible light irradiation. The excellent inactivation efficiency of the photocatalyst could be attributed to the higher charge carrier mobility, efficient electron-hole pair separation, and highvisible light harvesting ability. The Schottky heterojunction was proposed as a possible mechanism for the photoinactivation of E. coli. Further, the impacts of different dosages of nanocomposites (NCs) and varying pH on bacterial inactivation were studied under visible light exposure. The reusability and stability of the NCs were investigatedfor 6 consecutive cycles of photoinactivation and it showed excellent efficiency (91.16%) of the photocatalyst for prolonged usage. The real-time application was assessed using reclaimed wastewaterand the influence on the organic matter was determined using COD analysis. The proposed study offers a significant point reference for the practical application of photocatalysis forthe inactivation of antibiotic-resistant microbes present in water bodies and environmental wastewater.

Improved photocatalytic disinfection performance of graphitic carbon nitride through hybridization with humic acid /zinc peroxide: A synergistic generation of antimicrobial reactive oxygen species

Photocatalytic disinfection of bacteria using photosensitive nanomaterials is an efficient method for bacteria inactivation and is considered a beneficial alternative to chemical disinfectants that produce harmful by-products. However, due to the limited application scope of photocatalysts, the antibacterial efficiency remains unsatisfactory. To enhance the photocatalytic efficiency of the non-metal photosensitizer, graphitic carbon nitride (g-C3N4) nanosheets, they were composited with a metal-based photosensitizer, zinc peroxide (ZnO2) nanoparticles, with the aim of humic acid (HA). Besides the self-generating ability of H2O2 by ZnO2 in an aqueous medium, its deposition over g-C3N4 nanosheets enhances visible light harvesting and increases both surface area and active sites, thereby enhancing photocatalytic efficiency. The resulting composite, g-C3N4/ZnO2, produced more H2O2, •OH, and O2•- radicals than either component when exposed to visible light. Moreover, the photocatalyst demonstrated enhanced photocatalytic disinfection efficacy against Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) under dark conditions compared to pure g-C3N4 nanosheets. However, a notably greater antibacterial activity was observed when the nanocomposites were subjected to light irradiation. FESEM images and live-dead assays revealed the physical contact of the nanocomposite with the surface of bacterial cells and the loss of cell membrane integrity. Furthermore, it was observed that there was greater cellular uptake of nanocomposites into cells and the generation of reactive oxygen species (ROS) under light irradiation compared to similar conditions in the dark, leading to an increased photoinactivation rate of bacteria. The enhanced photocatalytic and antibacterial activities of g-C3N4/ZnO2 nanocomposites make them attractive for a range of applications, including use in nanomedicine and environmental surface disinfection.

Efficient water disinfection accelerated by polymerization-degree-controlled graphitic carbon nitride under visible light

In the quest for continuously raising the quality of drinking water, the exploration for effective photocatalysts to facilitate photocatalytic water disinfection remains an enduring challenge. Here, we demonstrate that by easily adjusting the polymerization degree of graphitic carbon nitride (g-C3N4), g-C3N4 itself can attain an exceptional photoactivity for disinfecting various waterborne bacteria. By synergistically integrating experimental investigations with density functional theory calculations, we propose that fine-tuning the polymerization degree of g-C3N4 confers remarkable attributes conducive to the specific generation of H2O2 through a two-electron reduction pathway. This ultimately culminates in the attainment of efficient water disinfection, that 7-log reduction in E. coli concentration is achieved within 180 min, in the absence of any additional cocatalyst. This work may shed light on developing highly efficient g-C3N4-based photocatalytic disinfectants for water disinfection applications.

Construction of the Z-scheme Cu2O-Ag/AgBr heterostructures to enhance the visible-light-driven photocatalytic water disinfection and antibacterial performance

Constructing Z-scheme heterojunctions is considered to be an excellent strategy for enhancing the photocatalytic performance of compounds. In this study, visible-light-driven (VLD) Z-scheme Cu2O-Ag/AgBr photocatalysts with high efficiency were constructed with the aid of a photo-reduction precipitation technique. The photocatalytic properties and different mass fractions of Ag/AgBr nanoparticles were in situ deposited on the surface of an octahedral Cu2O. The results indicated that nearly 98.7% methyl orange (MO) could be degraded within 90 min using Cu2O-Ag/AgBr. Due to the reactive oxygen species (ROS) generated by Cu2O-Ag/AgBr, 99% antibacterial efficiency was achieved by Cu2O-Ag/AgBr against Gram-positive/Gram-negative bacteria. After four consecutive cycles of Cu2O-Ag/AgBr, the photocatalyst remained relatively stable and exhibited excellent stability and reusability. Various analyses demonstrated loading Ag/AgBr nanoparticles into composites can enhance their optical properties, accelerating the transport of photogenerated carriers. The Z-scheme heterojunction between Ag/AgBr and Cu2O provided higher redox capability. Moreover, the photocatalytic properties of the composites can be boosted via the surface plasmon resonance (SPR) effect from a small amount of metallic Ag. Lastly, the mechanism of photocatalysis occurrence was elucidated by exploring the essential reaction substances in the process, and primary active species were discovered to be the photogenerated holes (h+), •O2‾, and •OH. This study indicated that the as-prepared Cu2O-Ag/AgBr exhibited great potential to be applied in wastewater treatment.

Enhanced Photocatalytic Properties of All-Organic IDT-COOH/O-CN S-Scheme Heterojunctions Through π-π Interaction and Internal Electric Field.

Herein, we present a distinct methodology for the in situ electrostatic assembly method for synthesizing a conjugated (IDT-COOH)/oxygen-doped g-C3N4 (O-CN) S-scheme heterojunction. The electron delocalization effect due to π-π interactions between O-CN and self-assembled IDT-COOH favors interfacial charge separation. The self-assembled IDT-COOH/O-CN exhibits a broadened visible absorption to generate more charge carriers. The internal electric field between the IDT-COOH and the O-CN interface provides a directional charge-transfer channel to increase the utilization of photoinduced charge carriers. Moreover, the active species (•O2-, h+, and 1O2) produced by IDT-COOH/O-CN under visible light play important roles in photocatalytic disinfection. The optimum 40% IDT-COOH/O-CN can kill 7-log of methicillin-resistant Staphylococcus aureus (MRSA) cells in 2 h and remove 88% tetracycline (TC) in 5 h, while O-CN only inactivates 1-log of MRSA cells and degrades 40% TC. This work contributes to a promising method to fabricate all-organic g-C3N4-based S-scheme heterojunction photocatalysts with a wide range of optical responses and enhanced exciton dissociation.

Multifunctional capabilities of radio frequency sputtered GO-TiO2 nanocomposite ultra-thin films

The work presents the successful synthesis of ultra-thin Graphene Oxide-Titanium (GOT) nanocomposite films using radio frequency sputtering. It was employed a thorough characterization encompassing structural, optical, and morphological aspects, with a focus on practical applications such as photocatalysis, anti-corrosion, anti-reflective properties, and superhydrophobicity (PAAS). Notably, the GOT film exhibited outstanding photocatalytic efficiency, achieving a significant 96% photodegradation rate, and offering promise for environmental remediation. Additionally, it demonstrated excellent visible-light-induced photocatalytic disinfection against E. coli K12 contamination. Furthermore, the film displayed notable corrosion resistance, a fivefold improvement over pristine surfaces, and excellent anti-reflective properties with 98% transmittance in the visible light range, making it suitable for advanced optical devices with multifunctional benefits.