Search

Three-dimensional (3D) hierarchical microspheres of Bi

Chemical doping and coating have been considered as efficient semiconductor physics strategies to modulate the physical, chemical, and biological properties of materials for the required applications. In this study, cetyltrimethylammonium bromide (CTAB) stabilizer-capped nickel-doped cupric oxide (NixCu1−xO) nanoparticles (NPs) with different doping concentrations (0.0 ≤ x ≤ 0.05) were synthesized via a one-step rapid and low-cost solvothermal synthesis route. The as-synthesized CTAB-capped NixCu1−xO NPs have been sightseen for their structural/morphological, optical/dielectric, and antimicrobial properties using XRD/SEM/TEM, FT-IR/UV–visible/Impedance spectroscopies, and Agar well diffusion method, respectively. Relevant results show enhanced optical, dielectric and antimicrobial properties with Ni doping due to the smaller size effect. Importantly, in vitro examination, the antimicrobial activity of the grown NPs was evaluated against four microbial species, exhibits that the CTAB-capped Ni-doped CuO NPs possess a command antimicrobial toxicity to Staphylococcus aureus (25923-ATCC), Klebsiella pneumoniae (700603-ATCC), and Escherichia coli (25922-ATCC) and an intermediate performance towards Candida albicans (24433-ATCC). The minimum inhibitory concentration (MIC) assay for the obtained CTAB-Ni0.05Cu0.95O sample upon S. aureus or K. pneumoniae pathogens reaches extremely as low as 5 μg ml−1 for all reported CuO NPs. The improved dose-dependent antimicrobial effect has been found to be strongly dependent on the particle size, surface morphology, elemental compositions, and surface bio-functionality of the catalytic nanomaterials. Additionally, Ni-dopant, CTAB-stabilizer, and binding of Cu+/Cu2+ ions with respiratory enzymes collectively produce an excess amount of reactive oxygen species (ROS) in the bacterial culture medium, which determines a predominant antibacterial mechanism for bacterial cells damage. Overall, these inorganic (NixCu1−xO) NPs with antimicrobial cationic surfactant (CTAB) have advantages to use as a functionalized disinfection nanoagent to control the microbial infections in the healthcare sector together with various electronic and photonic medical diagnoses.

In recent years, a temperature-sensitive hydrogel was reported as a promising draw agent in forward osmosis (FO) technology. PEG, acts as porogen, as an enabler to improve the swelling property of hydrogels. From FO test, the addition of porogen to the hydrogel can improve the water flux of FO by increasing the swelling properties of the hydrogel. And the hydrogel modified with porogen improves the concentration efficiency of wastewater from 1.09 to 1.124 times, indicating that the modification of the hydrogel by the porogen has positive significance for FO technology. In this study, an advanced hydrogel was synthesized via physical copolymerization by using N-isopropylacrylamide and sodium acrylate. The internal structure was investigated by SEM test where it was found that that porogens have different mechanisms of action on hydrogel performance: Porogen affects the swelling property of hydrogel by changing the internal network structure through physical “occupation”. The effect of porogen concentration is to act on the porosity of hydrogel, while the main effect of the molecular weight of porogen on the hydrogel structure is by altering the pore size.

Luminescent solar concentrators (LSCs) provide a transformative approach to integrating photovoltaics into a built environment. In this paper, we report thin-film LSCs composed of intramolecular charge transfer fluorophore (DACT-II) and discuss the effect of two polymers, polymethyl methacrylate (PMMA), and poly (benzyl methacrylate) (PBzMA) on the performance of large-area LSCs. As observed experimentally, DACT-II with the charge-donating diphenylaminocarbazole and charge-accepting triphenyltriazine moieties shows a large Stokes shift and limited re-absorption losses in both polymers. Our results show that thin-film LSC (10 × 10 × 0.3 cm3) with optimized concentration (0.9 wt%) of DACT-II in PBzMA gives better performance than that in the PMMA matrix. In particular, optical conversion efficiency (ηopt) and power-conversion efficiency (ηPCE) of DACT-II/PBzMA LSC are 2.32% and 0.33%, respectively, almost 1.2 times higher than for DACT-II/PMMA LSC.

Lead-free piezoelectric ceramics, (Bi0.70Ba0.35)(Fe0.65Ti0.35)O3 (BBFT), were fabricated via a solid-state reaction method and then treated using different heat-treatment processes (furnace cooling, air quenching (AQ), and water quenching). In all these ceramics, the X-ray diffraction analysis revealed morphotropic phase boundaries between the rhombohedral and tetragonal phases. Changes in the average grain size, relative density, and electrical properties in the BBFT–AQ composition were observed. For the optimum BBFT–AQ ceramic, significantly enhanced dynamic (d33* ~ 340 pm/V) and static (d33 ~ 165 pC/N) piezoelectric coefficients were obtained. Moreover, the d33* increased to 40% (d33* ~ 475 pm/V) with increasing temperature from 25 °C to 75 °C upon the application of a 4.0 kV/mm electric field. The related defect states were established by the variation in the transition of Fe3+ to Fe2+ and OV or $$V_{O}^{ \bullet \bullet }$$ concentration observed using X-ray photoelectron spectroscopy analysis. These factors are directly related to the electromechanical response enhancement in the BBFT piezoceramics. This study provides a paradigm for a deeper analysis of particular scientific heat-treatment mechanisms and the enhancement of functional properties in BBFT ceramics.

In order to further improve its photocatalytic activity, the BiOI microspheres were activated by a synchronous coupling of Bi metal and graphene under solvothermal conditions. The effects of the synthesis temperature (160–200 °C) on crystallinity, morphology, and photocatalytic activity were studied in particular. As expected, the ternary Bi-BiOI/graphene photocatalyst synthesized at 180 °C exhibited higher photocatalytic activity for NO oxidation removal under visible light irradiation than individual BiOI, and binary Bi-BiOI and BiOI/graphene composites. The photocatalytic efficiency for the NO removal of the ternary Bi-BiOI/graphene photocatalyst synthesized at 180 °C reached 51.8% within 30 min of visible light irradiation. The enhanced photocatalytic activity of the ternary Bi-BiOI/graphene photocatalyst is attributed to (I) the efficient transfer of photo-generated electrons from BiOI and Bi to graphene, leading to the effective separation of the photo-generated electron-hole pairs and (II) the surface plasmon resonance effect of Bi nanoparticles in the composite photocatalyst. Furthermore, the results of the scavenger experiments and DMPO-ESR spin-trapping measurements reveal that O2− radical species play the most critical role and holes serve as a secondary active species in the oxidative removal process of NO by 180BOI/GR composite under visible light irradiation.

In this study, we fabricated a novel hybrid photocatalyst (CD-BVO/rGH) by coupling carbon dot (CD)-decorated BiVO4 (BVO) with a reduced graphene hydrogel (rGH). The CD-BVO/rGH photocatalyst significantly enhanced the photocatalytic efficiency for tetracycline hydrochloride (TCH) degradation compared with pure BVO and BVO/rGH under simulated solar irradiation. CD-BVO/rGH also showed a substantial performance in the photocatalytic reduction of CO2. The enhanced photocatalytic activity of CD-BVO/rGH is attributed to synergistic effects, such as better light energy utilization via the upconversion effects of the CDs and the enhanced migration and separation of photoexcited carriers by the three-dimensional (3D) network structure of the rGH. The systematic analysis of the band structure, electron spin resonance, and free radical trapping revealed that h+ and O2– mediate the final photocatalytic degradation of pollutants. Our results provide insight into the design and construction of highly efficient hybrid photocatalysts combined with functional carbon nanostructures to enhance the photocatalytic activity for the photodegradation of environmental pollutants and CO2 reduction.

The efficient removal of antibiotics in water is essential to protect aquatic environment as antibiotics are some of the most hazardous pollutants in water. Herein, we report the synthesis of a novel N-GNDs/Ag/BiVO4 ternary photocatalyst consisting of BiVO4 coupled with Ag nanoparticles (Ag-NPs) and nitrogen-doped graphene nanodots (N-GNDs) to degrade and mineralize tetracycline hydrochloride (TC•HCl) in water. The ternary photocatalyst shows higher photocatalytic degradation of TC•HCl under full spectrum light than pure BiVO4. Based on the morphology, crystalline structure, physicochemical properties, and photoelectrochemical behavior of the ternary photocatalyst, the enhanced photocatalytic performance is attributed to the upconversion effect of N-GNDs and the localized surface plasmon resonance (LSPR) effect of Ag-NPs. Thus, the synergetic effects expand the absorption range of light and significantly promotes the separation of photoexcited carriers. Further, a possible photocatalytic reaction mechanism of TC•HCl degradation over N-GNDs/Ag/BiVO4 is discussed via through investigation of the charge carrier migration, active species, and intermediates in the degradation processes.

The two key factors such as light adsorption and separation of charge carriers in photocatalysts play crucial roles in determining the overall photocatalytic efficiency. Herein, we report synergetic effects of Fe-doping and Au nanoparticles (Au-NPs) deposition on the photocatalytic activity of the modified Bi4O5Br2 (BOB) nanosheets photocatalyst for Bisphenol A degradation and gaseous NO oxidative removal. Fe-doped BOB nanosheets decorated with Au-NPs are synthesized by a two-step chemical method. It was found that the Fe-doped BOB sample decorated with Au-NPs (Au-Fe-BOB) exhibits higher photocatalytic activity than the BOB, Fe-doped BOB, and Au-NPs-loaded BOB samples. Internal Fe-doping in the BOB enhanced the visible light absorption and the separation efficiency of photogenerated charge carriers acting as a scavenger. Moreover, the decorated Au-NPs in the composite photocatalyst extended the light adsorption in the range of visible and near- infrared light due to surface plasmon resonance effect of Au-NPs. The spin trapping measurements of Au-Fe-BOB composite photocatalyst show that the •O2− is a main reactive species during the photocatalytic reaction under visible-light irradiation. The excellent photocatalytic efficiency and stability of Au-Fe-BOB with visible-light response allow to be readily constructed and applied for practical removal of various pollutants using solar light in the future.