Facile synthesis of lead iodide nanostructures by microwave irradiation technique and their structural, morphological, photoluminescence and dielectric studies

Bioinspired "cage traps" for closed-loop lead management of perovskite solar cells under real-world contamination assessment

Despite the remarkable progress made in perovskite solar cells, great concerns regarding potential Pb contamination risk and environmental vulnerability risks associated with perovskite solar cells pose a significant obstacle to their real-world commercialization. In this study, we took inspiration from the ensnaring prey behavior of spiders and chemical components in spider web to strategically implant a multifunctional mesoporous amino-grafted-carbon net into perovskite solar cells, creating a biomimetic cage traps that could effectively mitigate Pb leakage and shield the external invasion under extreme weather conditions. The synergistic Pb capturing mechanism in terms of chemical chelation and physical adsorption is in-depth explored. Additionally, the Pb contamination assessment of end-of-life perovskite solar cells in the real-world ecosystem, including Yellow River water and soil, is proposed. The sustainable closed-loop Pb management process is also successfully established involving four critical steps: Pb precipitation, Pb adsorption, Pb desorption, and Pb recycling. Our findings provide inspiring insights for promoting green and sustainable industrialization of perovskite solar cells.

The role of Pb oxidation state of the precursor in the formation of 2D perovskite microplates

Two-dimensional (2D) lead halide perovskites are an exciting class of materials currently being extensively explored for photovoltaics and other optoelectronic applications. Their ionic nature makes them ideal candidates for solution processing into both thin films and nanostructured crystals. Understanding how 2D lead halide perovskite crystals form is key towards full control over their physical properties, which may enable new physical phenomena and devices. Here, we investigate the effects of the Pb oxidation state of the initial inorganic precursor on the growth of pure-phase (n = 1) - Popper 2D perovskite BA₂PbI₄ in single-step synthesis. We examine the different crystallisation routes in exposing PbO₂ and PbI₂ powders to a BAI : IPA organo-halide solution, by combining in situ optical microscopy, UV-VIS spectroscopy and time-resolved high performance liquid chromatography. So far, works using PbO₂ to synthesise 3D LHPs introduce a preceding step to reduce PbO₂ into either PbO or PbI₂. In this work, we find that BA₂PbI₄ is directly formed when exposing PbO₂ to BAI : IPA without the need for an external reducing agent. We explain this phenomenon by the spontaneous reduction/oxidation of PbO₂/BAI that occurs under iodine-rich conditions. We observe differences in the final morphology (rectangles vs. octagons) and nanocrystal growth rate, which we explain through the different chemistry and iodoplumbate complexes involved in each case. As such, this work spans the horizon of usable lead precursors and offers a new turning knob to control crystal growth in single-step LHP synthesis.

Recent Trends in Hydroxyapatite Supplementation for Osteoregenerative Purposes

Bone regeneration has gained attention in the biomedical field, which has led to the development of materials and synthesis methods meant to improve osseointegration and cellular bone activity. The properties of hydroxyapatite, a type of calcium phosphate, have been researched to determine its advantages for bone tissue engineering, particularly its biocompatibility and ability to interact with bone cells. Recently, the advantages of utilizing nanomolecules of hydroxyapatite, combined with various substances, in order to enhance and combine their characteristics, have been reported in the literature. This review will outline the cellular and molecular roles of hydroxypatite, its interactions with bone cells, and its nano-combinations with various ions and natural products and their effects on bone growth, development, and bone repair.

Synthesis and Characterization of Yttrium-Doped Hydroxyapatite Nanoparticles and Their Potential Antimicrobial Activity

This study reports a detailed analysis of the yttrium doping effects into hydroxyapatite (HAp) nano-structures at different amounts (e.g., 0, 1, 2.5, 5, 7.5, 10, and 15%) on the structural, spectroscopic, dielectric, and antimicrobial properties. For this purpose, seven HAp samples having the Y-contents mentioned above were prepared using the microwave-assisted sol-gel precipitation technique. The structure of synthesized samples was fully described via X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transforms infrared (FTIR). Raman spectroscopy and dielectric measurements were used to characterize the spectroscopic properties. Furthermore, the samples’ antimicrobial features have been assisted through the agar disk diffusion technique. This study showed that the crystallinity decreased with the adding of Y-ions inside the HAp matrix. The Y-contents have influenced the crystallite size, lattice parameters, dislocation density, lattice strain, and unit cell volume. The surface morphology is composed of the agglomerated smaller particles. Remarkable changes in the dielectric properties were observed with the adding of Y-ions. The alternating current conductivity obeys the Jonscher’s relation. Y-doped hydroxyapatite nanoparticles have a considerable inhibitory effect against bacteria and fungi (Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans). The Y-doped hydroxyapatite nanoparticles are a promising material for bone cement engineering with a potential bio-activity

A facile synthesis of Au-nanoparticles decorated PbI2 single crystalline nanosheets for optoelectronic device applications

This research communication presents a rapid and facile microwave-assisted synthesis of single crystalline nanosheets (SCNSs) of hexagonal lead iodide (PbI₂) decorated with Au nanoparticles, a potential optoelectronics material. Homogeneous low dimensional AuNP decoration in PbI₂ resulted in a new absorption band at ~604 nm and a shift in band gap from 3.23 to 3.00 eV. The significant enhancement of photoluminescent (PL) intensity observed in the AuNP-PbI₂ SCNSs is attributed to the coupling of the localized surface plasmon resonanzce of AuNP leading to improved excitation and emission rates of PbI₂-SCNSs in the region of the localized electromagnetic field. The Au-PbI₂ SCNSs display a compelling increment in photoconductivity, and its fabricated photodetector showed a stable and switchable photo-response. Due to ease of synthesis and enhanced photoconductivity along with appealing PL features, Au-PbI₂ SCNS has the potential to be used as a material of choice when fabricating an optoelectronic devices of high performance.

Tailoring the structural, morphological, optical and dielectric properties of lead iodide through Nd3+ doping

Hexagonal single crystal nanosheets of Nd³⁺ doped PbI₂ were effortlessly synthesized via microwave-assisted technique under a power of 700 W and in a duration of 15 minutes with a homogeneous morphology. X-ray diffraction, energy dispersive X-ray spectroscope, scanning electron microscope, FT-Raman, UV-Visible, photoluminescence and dielectric measurement were employed to study the product. High purity, single phase and presence of Nd³⁺ doping was confirmed. SEM study confirm the formation of nanorods and single crystal nanosheets of very few nanometers in size. Robust vibrational analysis has been carried out and the observed bands are assigned to the vibration modes of E₂¹, A₁¹, A₁², 2E₂¹ and 2E₁¹, respectively. These bands are red-shifted when compare to the corresponding bulk values which indicate relaxed nanostructure formation and occurrence of confinement effect. The thickness of the synthesized single crystal nanosheets are found to be in the range of ~20 to 30 nm. The energy band gap was calculated and found to be 3.35, 3.34, 3.42 and 3.39 eV for pure, 1, 3 and 5% Nd³⁺ doped lead iodide, respectively. The clear blue luminescence has been observed at 440 nm and 466 nm when excited at 250 nm and 280 nm respectively. Dielectric and ac electrical conductivity was also measured and discussed.

Facile microwave-assisted synthesis of Te-doped hydroxyapatite nanorods and nanosheets and their characterizations for bone cement applications

In this work, the authors have fabricated the nanorods and nanosheets of pure and Te-doped HAp with different Te concentrations (0.04, 0.08, 0.16, 0.24wt%) by microwave-assisted technique at low temperature. The crystallite size, degree of crystallinity and lattice parameters are calculated. FE-SEM study confirms that the fabricated nanostructures are nanorods of diameter about 10nm in undoped and at low concentration of Te doping. However, at and higher concentration, it becomes nanosheets of about 5nm thickness. X-ray diffraction, FT-IR and FT-Raman studies shows that the prepared products are of HAp and Te has been successfully incorporated. From EDX the Ca/P molar ratio of the pure HAp is about 1.740, while this ratio for 0.04, 0.08, 0.16, 0.24 wt% Te doped is about 1.53, 1.678, 1.724, 1.792, respectively. Crystallite size was found to be increased with Te doping from 15nm to 62nm. The value of dielectric constant is found to be enhanced at higher concentrations of Te. The values of linear absorption coefficient were also determined and show that the prepared material with Te doping is more absorbable than pure and will be highly applicable in radiation detection applications. Furthermore, the antimicrobial potential of pure and Te doped HAp was examined against some Gram- negative and positive bacteria and fungi by agar disk diffusion method. The results demonstrated that the antimicrobial activity of Te doped HAp is stronger than that of pure HAp where it exhibited the highest activity against Bacillus subtilis>Candida albicans>Shigella dysenteriae.