Interfacial regulation of BiOI@Bi2S3/MXene heterostructures for enhanced photothermal and photodynamic therapy in antibacterial applications.

Developing environmentally friendly, broad-spectrum, and long-lasting antibacterial materials remains challenging. Our ternary BiOI@Bi2S3/MXene composites, which exhibit both photothermal therapy (PTT) and photodynamic therapy (PDT) antibacterial properties, were synthesized through in-situ vulcanization of hollow flower-shaped BiOI on the surface of two-dimensional Ti3C2 MXene. The unique hollow flower-shaped BiOI structure with a high exposure of the (001) crystal plane amplifies light reflection and scattering, offering more active sites to improve light utilization. Under 808 nm irradiation, these composites achieved a photothermal conversion efficiency of 57.8 %, boosting the PTT antibacterial effect. The heterojunction between Bi2S3 and BiOI creates a built-in electric field at the interface, promoting hole and electron transfer. Significantly, the close-contact heterogeneous interface enhances charge transfer and suppresses electron-hole recombination, thereby boosting PDT bacteriostatic performance. EPR experiments confirmed that ∙O2- and •OH radicals play major roles in photocatalytic bacteriostatic reactions. The combined antibacterial action of PTT and PDT led to efficiencies of 99.7 % and 99.8 % against P. aeruginosa and S. aureus, respectively, under 808 nm laser irradiation. This innovative strategy and thoughtful design open new avenues for heterojunction materials in PTT and PDT sterilization. STATEMENT OF SIGNIFICANCE: Photodynamic and photothermal therapy is a promising antibacterial treatment, but its efficiency still limits its application. To overcome this limitation, we prepared three-dimensional heterogeneous BiOI@Bi2S3/MXene nanocomposites through in-situ vulcanization of hollow flower-shaped BiOI with a high exposure of the (001) crystal plane onto the surface of two-dimensional MXene material. The resulting ternary material forms a close-contact heterogeneous interface, which improves charge transfer channels, reduces electron-hole pair recombination, and amplifies photodynamic bacteriostatic performance. These nanocomposites exhibit photothermal conversion efficiency of 57.8 %, enhancing their photothermal bactericidal effects. They demonstrated antibacterial efficiencies of 99.7 % against P. aeruginosa and 99.8 % against S. aureus. Therefore, this study provides a promising method for the synthesis of environmentally friendly and efficient antibacterial materials.

Fabrication of direct Z-scheme Cu2O@V-CN (octa) heterojunction with exposed (111) lattice planes and nitrogen-rich vacancies for rapid sterilization.

The Z-scheme heterojunction has demonstrated significant potential for promoting photogenerated carrier separation. However, the rational design of all-solid Z-scheme heterojunctions catalysts and the controversies about carrier transfer path of direct Z-scheme heterojunctions catalysts face various challenges. Herein, a novel heterojunction, Cu2O@V-CN (octa), was fabricated using V-CN (carbon nitride with nitrogen-rich vacancies) in-situ electrostatic self-wrapping Cu2O octahedra. Density functional theory (DFT) calculations revealed that the separation of carriers across the Cu2O@V-CN (octa) heterointerface was directly mapped to the Z-scheme mechanism compared to Cu2O/V-CN (sphere). This is because the Cu2O octahedra expose more highly active (111) lattice planes with more terminal Cu atoms and V-CN with abundant nitrogen vacancies to form delocalized electronic structures like electronic reservoirs. This facilitates the wrapping of Cu2O octahedra by V-CN and protects their stability via tighter interfacial contact, thus enhancing the tunneling of carriers for rapid photocatalytic sterilization. These findings provide novel approaches for designing high-efficiency Cu2O-based photocatalytic antifoulants for practical applications.

Full solar spectrum-driven Cu2O/PDINH heterostructure with enhanced photocatalytic antibacterial activity and mechanism insight.

Marine biofouling hazards the sustainable development of the environment and has become a potential threat to environmental and ecological security. Photocatalytic antibacterial agents driven by the full solar spectrum are promising antifouling agents for environmental protection. The cuprous oxide/perylene-3,4,9,10-tetracarboximide (Cu2O/PDINH) heterostructure was successfully constructed by integrating p-type Cu2O and n-type PDINH to improve photocatalytic antibacterial efficiency. PDINH extended the absorption spectrum from ultraviolet to near-infrared, improving light utilization by 75 %. The Cu2O/PDINH heterostructure reduced the toxicity risk of Cu2O for environmental pollution, achieved full solar spectrum drive and overcame the inherent defect that Cu2O cannot produce singlet oxygen. The Cu2O/PDINH heterostructure exhibited excellent long-term and photocatalytic antibacterial activity with an antibacterial rate of > 90 % due to the sterilization of copper ions and the continuous generation of ROS driven by the full solar spectrum. This inorganic-organic Cu2O/PDINH heterostructure shows great application prospects in energy and the environment. The Cu2O/PDINH heterostructure with effective ROS increase and superior photocatalytic sterilization efficiency has great potential for environmentally friendly marine antifouling agents.

NIR-triggered photocatalytic and photothermal performance for sterilization based on copper sulfide nanoparticles anchored on Ti3C2Tx MXene.

Harmful bacterial flourish with the increase in environmental pollution and pose a great threat to human health. Thus, developing new and efficient antibacterial materials is imperative to reduce the pollution caused by traditional sterilization materials and improve sterilization efficiency. In this study, a new photocatalytic antibacterial material was developed to achieve an efficient antibacterial effect. Ti3C2Tx@CuS composites were synthesized by simple hydrothermal method, by which copper sulfide (CuS) nanoparticles were anchored on the surface of Ti3C2Tx to sharply improve the photocatalytic its antibacterial ability. Ti3C2Tx@CuS exhibits excellent antibacterial activity against Escherichia coli and Staphylococcus aureus with bactericidal rates of 99.6% and 99.1%, respectively. Photoluminescence spectroscopy (PL), decay time PL, photocurrent test, electrochemical impedance spectroscopy and finite element method showed that the formation of Ti3C2Tx@CuS heterojunction promoted the separation of electrons and holes, improved the electron transport efficiency, and elevated the generation of reactive oxygen species. Moreover, Ti3C2Tx@CuS has a stronger photothermal effect and causes more heat release than CuS to improve antibacterial performance. The Ti3C2Tx@CuS heterojunction has a broad application prospect in the disinfection and antibacterial fields.

Charge transfer channels of silver @ cuprous oxide heterostructure core-shell nanoparticles strengthen high photocatalytic antibacterial activity.

Marine biological fouling has always been a hot research topic. In this study, silver @ cuprous oxide (Ag@Cu2O) core-shell nanoparticles were synthesized via in-situ synthesis method and developed an outstanding antibacterial activity. The bacteriostasis efficiency of Ag@Cu2O reached to 99% and 98% against Staphylococcus aureus and Pseudomonas aeruginosa, respectively. The minimum inhibitory concentration of Ag@Cu2O decreased from 113.6 µg/mL to 56.8 µg/mL compared with Cu2O. Ag@Cu2O had better antibacterial activity than Cu2O with lower content of Cu2O and was more environment friendly. The heterostructure formed at the interface between Ag and Cu2O promoted the separation and diffusion of photogenerated electron-hole pairs through the charge transfer channel and promoted the generation of reactive oxygen species. The outstanding antibacterial activity of Ag@Cu2O was strongly depended on the generation of the reactive oxygen species. Density functional theory and finite element method calculations demonstrated that the structure of core-shell improved photocatalytic efficiency. Additionally, synergetic effect of released Ag+ and Cu2+ also enhanced the bacteriostasis rate and the long-term antifouling performance in 60 days. Hence, the synthesized core-shell Ag@Cu2O can be applied as novel antifoulants in the marine field.

Facile synthesis of BTA@NiCo2O4 hollow structure for excellent microwave absorption and anticorrosion performance.

A three-dimensional hollow NiCo2O4 structure was successfully prepared with a precipitation-hydrothermal method. A balance between magnetic and dielectric losses was achieved by using a hollow NiCo2O4 structure loaded with benzotriazole (BTA), and thus the performance of electromagnetic waves was attenuated. The minimum reflection loss value of BTA@NiCo2O4 at 16.01 GHz was -35.39 dB when the absorber thickness was 2 mm, at which the absorption bandwidth for an RL of less than -10 dB is as high as 4.64 GHz. The absorption mechanism was characterized by the synergy among interfacial polarization, multiple reflection, and dipole polarization enhancement between NiCo2O4 and BTA. Interestingly, the epoxy/BTA@NiCo2O4 coating not only exhibited an outstanding microwave absorption (MA) performance but also has excellent anticorrosion and self-healing properties, as shown by the results of electrochemical impedance spectroscopy and confocal laser scanning microscopy. This work would be very helpful to the development of novel coatings with excellent MA performance and anticorrosion and self-healing properties.