Evaluation of antibacterial activity and influencing factors of normal and nanostructured copper-based materials.

Background: Copper-based materials have garnered extensive recognition for their effective nature against microorganisms and their minimal toxicity. However, the evaluation for their antibacterial activity is still in its nascent stages, and the evaluation results based on existing criteria are not representative of real-world application. Aim: To evaluate the antibacterial activity and primary determinants of influence of copper-based materials in order to investigate their practical antibacterial activity and potential mechanisms of such materials. Methods: Staphylococcus aureus and Escherichia coli bacterial suspensions were applied via inoculation onto the surfaces of normal and nanostructured copper foil. Following incubation of the inoculated surfaces under diverse experimental conditions-including varying compositions of the bacterial suspension, the use of chemical neutralizers, the existence of organic interferents, and low temperature and humidity-surviving bacteria were enumerated. Using the scanning electron microscopy and X-ray photoelectron spectroscopy, the surface changes of copper-based materials were examined. Findings: Following 1 h of exposure to 37 °C and 90% relative humidity, Staphylococcus aureus was reduced by 4.45 log10 on normal copper foil, while all of the bacteria were eradicated on nanostructured copper foil. In addition, it was discovered that preparing a bacterial suspension with PBS results in a significant number of Escherichia coli fatalities during the test, whereas using TPS promotes the bacteria's normal growth. Furthermore, the outcomes of the antibacterial activity test were diminished when chemical neutralization was employed, and the presence of organic interferents had distinct impacts on normal copper foil and nanostructured copper foil. Additionally, low temperatures and humidity diminished the antibacterial activity of copper foil, whereas normal copper foil produced significantly better results. Conclusion: While copper-based materials exhibit robust antibacterial activity as determined by standard assays, their efficacy in real-world applications is subject to various influencing mechanisms. In order to objectively evaluate the antibacterial activity of copper-based materials and provide precise guidance for their development and practical application, it is essential to regulate test conditions with targeted.

Biological Visual Detection for Advanced Photocatalytic Oxidation toward Pesticide Detoxification.

Photocatalytic oxidation treatment is an emerging and fast developed eco-friendly, energy-saving, and efficient advanced oxidation technology for degrading hazardous pesticides. The conventional chemical detection to evaluate the effects for this process depends on the broken chemical structure, only giving residual content and product chemical composition. However, it misses direct visual detection on the toxicity and the quantitative analysis of pesticide detoxification. Here, we develop a novel strategy to combine photocatalytic oxidation with a zebrafish biological model to provide a direct visual detection on the environmental detoxification. The mortality or deformity of zebrafish embryos (ZEs) acts as an indicator. Over the irradiation duration threshold, the mortality of ZEs decreases to 23.3% for pure chlorothalonil (CTL-P) after photocatalytic oxidation treatment for 1 h, and the deformity reduces to 13.3% for commercial CTL (CTL-C) after 30 min and to 3.33% for tetramethylthiuram disulfide (TMTD) after 20 min. The toxicity of CTL-C and TMTD could be completely removed by photocatalytic oxidation treatment and causes no damage to the ZE developmental morphology. Chemical analyses demonstrate the degradation of CTL into inorganic compounds and TMTD into small organic molecules. Among these highlighted heterogeneous photocatalysts (g-C3N4, BiVO4, Ag3PO4, and P25), g-C3N4 exhibits the highest photocatalytic detoxification for CTL-P, CTL-C, and TMTD.

Preparation and Properties of Graphene/Nickel Composite Coating Based on Textured Surface of Aluminum Alloy.

This study carried out a novel duplex surface treatment on aluminum alloy base to explore the potential improvement of wear and corrosion resistance. Regular arrayed dimple surface texture (DST) and groove surface texture (GST) were fabricated by using laser processing on 6065 aluminum alloy matrix (6065Al). Electrochemical deposition of Ni and Graphene/Ni coatings on textured surface was then performed in electrolytes with concentrations of 0, 0.5, 1 and 1.5 mg graphene. Surface morphology such as diameter of dimple and width of groove measured by C-PSCN stereo microscope presents addition of graphene helps to refine and homogenize the coating. Corrosion resistant properties of the duplex surface treatment were examined by electrochemical corrosion tests and wear resistant properties were tested by UMT-Tribo Lab friction and wear tester in a dry sliding condition at room temperature. Electrochemical corrosion tests results show that the corrosion resistance of samples is related to the specific surface texture and the dimple texture can improve the electrical corrosion parameters, such as the electrode potential, greatly. Friction and wear tests show that the textured Gr/Ni electroplating coating with the 1.5 mg graphene content has best wear properties under vertical friction and each index, such as the coefficient of friction and wear trace width, are superior to other conditions of samples.

Inorganic-organic CdSe-diethylenetriamine nanobelts for enhanced visible photocatalytic hydrogen evolution.

Inorganic-organic hybrid nanomaterials, with excellent chemical and physical properties and technology applications, have attracted much attention in many fields. In the photocatalytic field, it is still a problem to find a stable, adjustable morphology and band gap and effective photocatalyst in utilizing solar energy conversion to hydrogen (H2) to solve the energy crisis. Herein, with the assistance of diethylenetriamine (DETA), the novel inorganic-organic CdSe-DETA hybrids with different morphology and adjustable band gap have been synthesised via simple microwave hydrothermal method. The morphological transformation mechanism involves the consumption of organic components controlled by the mixed precursor and subsequent self-assembly of residual inorganic components (CdSe). Under the visible light irradiation (λ > 420 nm), CdSe-18DETA nanobelt, showed the best photocatalytic H2 production activity (5.75 mmol·g-1·h-1), which is 3.03 times greater than that of pure CdSe (1.90 mmol·g-1·h-1). Moreover, after four cycles, the photocatalytic H2 production activity can still remain 91.27% of initial value, which indicates its good photocatalytic stability. Our results provide a promising approach for designing visible-light photocatalysts with efficient electron-hole separation and adjustable morphology and band gap.

Morphology dependent adsorption of methylene blue on trititanate nanoplates and nanotubes prepared by the hydrothermal treatment of TiO2.

The adsorption properties of two nanomorphologies of trititanate, nanotubes (TiNT) and plates (TiNP), prepared by the hydrothermal reaction of concentrated NaOH with different phases of TiO2, were examined. It was found that the capacity for both morphologies towards methylene blue (MB), an ideal pollutant, was extremely high, with the TiNP having a capacity of 130 mg/g, higher than the TiNT, whose capacity was 120 mg/g at 10 mg/L MB concentration. At capacity, the well-dispersed powders deposit on the floor of the reaction vessel. The two morphologies had very different structural and adsorption properties. TiNT with high surface area and pore volume exhibited exothermic monolayer adsorption of MB. TiNP with low surface area and pore volume yielded a higher adsorption capacity through endothermic multilayer adsorption governed by pore diffusion. TiNP exhibited a higher negative surface charge of -23 mV, compared to -12 mV for TiNT. The adsorption process appears to be an electrostatic interaction, with the cationic dye attracted more strongly to the nanoplates, resulting in a higher adsorption capacity and different adsorption modes. We believe this simple, low cost production of high capacity nanostructured adsorbent material has potential uses in wastewater treatment.

Carbon Nitride Supramolecular Hybrid Material Enabled High-Efficiency Photocatalytic Water Treatments.

Surface defects in relation to surface compositions, morphology, and active sites play crucial roles in photocatalytic activity of graphitic carbon nitride (g-C3N4) material for highly reactive oxygen radicals production. Here, we report a high-efficiency carbon nitride supramolecular hybrid material prepared by patching the surface defects with inorganic clusters. Fe (III) {PO4[WO(O2)2]4} clusters have been noncovalently integrated on surface of g-C3N4, where the surface defects provide accommodation sites for these clusters and driving forces for self-assembly. During photocatalytic process, the activity of supramolecular hybrid is 1.53 times than pure g-C3N4 for the degradation of Rhodamine B (RhB) and 2.26 times for Methyl Orange (MO) under the simulated solar light. Under the mediation of H2O2 (50 mmol L-1), the activity increases to 6.52 times for RhB and 28.3 times for MO. The solid cluster active sites with high specific surface area (SSA) defect surface promoting the kinetics of hydroxide radicals production give rise to the extremely high photocatalytic activity. It exhibits recyclable capability and works in large-scale demonstration under the natural sunlight as well and interestingly the environmental temperature has little effects on the photocatalytic activity.

A Graphene-like Oxygenated Carbon Nitride Material for Improved Cycle-Life Lithium/Sulfur Batteries.

Novel sulfur (S) anchoring materials and the corresponding mechanisms for suppressing capacity fading are urgently needed to advance the performance of Li/S batteries. Here, we designed and synthesized a graphene-like oxygenated carbon nitride (OCN) host material that contains tens of micrometer scaled two-dimensional (2D) rippled sheets, micromesopores, and oxygen heteroatoms. N content can reach as high as 20.49 wt %. A sustainable approach of one-step self-supporting solid-state pyrolysis (OSSP) was developed for the low-cost and large-scale production of OCN. The urea in solid sources not only provides self-supporting atmospheres but also produces graphitic carbon nitride (g-C3N4) working as 2D layered templates. The S/OCN cathode can deliver a high specific capacity of 1407.6 mA h g(-1) at C/20 rate with 84% S utilization and retain improved reversible capacity during long-term cycles at high current density. The increasing micropores, graphitic N, ether, and carboxylic O at the large sized OCN sheet favor S utilization and trapping for polysulfides.

A high efficient graphitic-C3N4/BiOI/graphene oxide ternary nanocomposite heterostructured photocatalyst with graphene oxide as electron transport buffer material.

It is important to reduce the recombination of electrons and holes and enhance charge transfer through fine controlled interfaces for advanced catalyst design. In this work, graphene oxide (GO) was composited with graphitic-C3N4 (g-C3N4) and BiOI forming GO/g-C3N4 and GO/BiOI heterostructural interfaces, respectively. GO, which has a work function between the conducting bands of g-C3N4 and BiOI, is used as a buffer material to enhance electron transfer from g-C3N4 to BiOI through the GO/g-C3N4 and GO/BiOI interfaces. The increased photocurrent and reduced photoluminescence indicate efficient reduction of electron and hole recombination under the successful heterostructure design. Accordingly, the introduction of GO as a charge transfer buffer material has largely enhanced the photocatalytic performance of the composite. Thus, introducing charge transfer buffer materials for photocatalytic performance enhancement has proved to be a new strategy for advanced photocatalyst design.

Sonication assisted preparation of graphene oxide/graphitic-C3N4 nanosheet hybrid with reinforced photocurrent for photocatalyst applications.

Graphitic C3N4 (g-C3N4), as an advanced metal free photocatalyst, is known to be poorly exfoliated and dispersed in water from its powder form which has a layered structure, the intrinsic plane structure is not destroyed, and this has largely limited its application. In this work, we report our progress on successful sonication exfoliation of g-C3N4 nanosheets in graphene oxide (GO) aqueous solution. By making use of the substrate character of GO, g-C3N4 nanosheets of unvaried intrinsic structure were exfoliated and anchored on the GO surface, resulting in a GO/g-C3N4 hybrid. Moreover, the photocurrent of the hybrid was largely reinforced at the optimal weight fraction of GO. As a result, the corresponding photocatalytic performance of the hybrid with optimized photocurrent character was largely improved.

Graphene oxide capturing surface-fluorinated TiO2 nanosheets for advanced photocatalysis and the reveal of synergism reinforce mechanism.

Surface-fluorinated TiO2 (F-TiO2) nanosheets with exposed (001) facets were synthesized from a scalable hydrothermal treatment assisted by a specific stabilization effect of fluorine ions on the (001) facets. Assembly of F-TiO2 on graphene oxide (GO) sheets into GO/F-TiO2 hybrid in aqueous solution was further achieved by making use of the surfactant role of GO. Photocatalytic properties of GO/F-TiO2 hybrid were evaluated under 365 nm UV light irradiation for photodegradation of methylene blue (MB). An optimal GO content has been determined to be 3 wt%, and the corresponding apparent pseudo-first-order rate constant Kapp is 0.0493 min(-1), 3 times and 4 times more than that of pure TiO2 nanosheets and commercial P25 photocatalyst, respectively. To reveal the synergism reinforce mechanism of GO/F-TiO2 hybrid, photo absorption, surface absorption, and the photoelectrochemical current properties have been intensively studied. We found that enhanced electron-hole separation has been the key issue for the reinforcement of photocatalytic performance. F-TiO2 with exposed (001) facet has stronger electron-hole separation resulting in a higher photoelectrochemical current than that of P25 photocatalyst. Moreover, hybridization of F-TiO2 with GO could further increase the photoelectrochemical current and the largest current for the optimal weight fraction of GO is in good accordance with the photocatalysis performance. The GO/F-TiO2 interface junction that favors the electron-hole separation was attributed to the photoelectrochemical current enhancement.

Facile synthesis of a surface plasmon resonance-enhanced Ag/AgBr heterostructure and its photocatalytic performance with 450 nm LED illumination.

In this paper, a plasmonic Ag/AgBr heterostructure was reduced by AgBr, which was successfully synthesized by a facile hydrothermal process at a temperature as low as 90 °C. The morphological and structural observation, crystallinity and optical performance of the products grown were carried out by using scanning electron microscopy, X-ray diffraction, energy dispersive spectrometry and UV-vis diffuse reflectance spectroscopy. The photocatalytic activities of Ag/AgBr heterostructures were evaluated by the degradation of methylene blue under 450 nm LED arrays. The results revealed that the plasmonic Ag/AgBr heterostructures exhibited much higher photocatalytic activities than pure AgBr and commercial Degussa P25. The visible-light photocatalytic activity enhancement of Ag/AgBr heterostructures could be attributed to the surface plasmon resonance and its synergistic effect on the photosensitive AgBr. Furthermore, a mechanism of the plasmon synergistically enhanced photocatalytic process was proposed.

Self-regenerated solar-driven photocatalytic water-splitting by urea derived graphitic carbon nitride with platinum nanoparticles.

A natural self-regeneration step for urea derived graphitic carbon nitride with platinum nanoparticles is found by simply opening the system to air in the dark under ambient conditions, following its solar-driven hydrogen production. The produced peroxides deactivate the graphitic carbon nitride. Release of weakly bound peroxides on the polymeric semiconductor surface is a crucial process for regeneration.

Highly stable air working bimorph actuator based on a graphene nanosheet/carbon nanotube hybrid electrode.

A RGO/CNT hybrid electrode of porous structure is prepared through a surfactant-free solution method to construct a bimorph ionic actuator, showing wide frequency range responsive and highly repeatable (over a million times) and stable bending actuation performance.

Large volume variation of an anisotropic graphene nanosheet electrochemical-mechanical actuator under low voltage stimulation.

Large volume variation of electrode materials is important for actuator design. A graphene nanosheet membrane of paralleled structure could provide large volume variation as high as 98% by controlling its interspace distance through ionic liquid pre-expanding treatment.

Supramolecular self-assembly of biopolymers with carbon nanotubes for biomimetic and bio-inspired sensing and actuation.

Biopolymers are important natural multifunctional macromolecules for biomimetic and bio-inspired advanced functional material design. They are not only simple dispersants for carbon nanotube stabilization as they have been found to have specific interactions with carbon nanotubes. Their molecular activity, orientation and crystallization are influenced by the CNTs, which endow their composites with a variety of novel sensing and actuation performances. This review focuses on the progress in supramolecular self-assembly of biopolymers with carbon nanotubes, and their advances in sensing and actuation. To promote the development of advanced biopolymer/CNT functional materials, new electromechanical characteristics of biopolymer/CNT composites are discussed in detail based on the relationship between the microscopic biopolymer structures and the macroscopic composite properties.

Electromechanical actuation with controllable motion based on a single-walled carbon nanotube and natural biopolymer composite.

This paper reports novel electromechanical behavior for a natural biopolymer film due to the incorporation of a conductive carbon nanotube network. Through simple solution blending and casting, high weight fraction single-walled carbon nanotube-chitosan composite films were fabricated and exhibited electromechanical actuation properties with motion controlled by low alternating voltage stimuli in atmospheric conditions. Of particular interest and importance is that the displacement output imitated perfectly the electrical input signal in terms of frequency (<10 Hz) and waveform. Operational reliability was confirmed by stable vibration testing in air for more than 3000 cycles. Proposed electrothermal mechanism considering the alternating current-induced periodic thermal expansion and contraction of the composite film was discussed. The unique actuation performance of the carbon nanotube-biopolymer composite, coupled with ease of fabrication, low driven voltage, tunable vibration, reliable operation, and good biocompatibility, shows great possibility for implementation of dry actuators in artificial muscle and microsystems for biomimetic applications.

Large-scale aligned carbon nanotubes from their purified, highly concentrated suspension.

Large-scale aligned single-walled carbon nanotube (SWCNT) composite membranes have been successfully prepared from highly concentrated purified SWCNT suspensions. Biopolymer dispersant gellan gum was used to achieve aqueous dispersion of highly concentrated SWCNTs, which can be used to form the SWCNT liquid crystal phase. To achieve alignment of SWCNTs, purification of SWCNTs is found to be very important. Purification was achieved by a facile and nondestructive physical method that can prepare large volumes of SWCNTs in high yield for experimental use. Composite membranes of aligned SWCNTs could be obtained by simple evaporation SWCNT liquid crystal. The orientation direction of aligned SWCNTs was controlled by mechanical shearing of SWCNT liquid crystal. The aligned SWCNTs in the biopolymer matrix were observed by electron microscopy, and the anisotropic electrical performance of this composite thin film has been characterized.