Scanning Transmission Electron Microscopy Techniques Research Articles

Giant Uniaxial Magnetocrystalline Anisotropy in SmCrGe3.

Magnetic anisotropy is a crucial characteristic for enhancing the spintronic device performance. The synthesis of SmCrGe3 single crystals through a high-temperature solution method has led to the determination of uniaxial magnetocrystalline anisotropy. Phase verification was achieved by using scanning transmission electron microscopy (STEM), powder, and single-crystal X-ray diffraction techniques. Electrical transport and specific heat measurements indicate a Curie temperature (TC) of approximately 160 K, while magnetization measurements were utilized to determine the anisotropy fields and constants. Curie-Weiss fitting applied to magnetization data suggests the contribution of both Sm and Cr in the paramagnetic phase. Additionally, density functional theory (DFT) calculations explored the electronic structures and magnetic properties of SmCrGe3, revealing a significant easy-axis single-ion Sm magnetocrystalline anisotropy of 16 meV/fu. Based on the magnetization measurements, easy-axis magnetocrystalline anisotropy at 20 K is 13 meV/fu.

Correlated 4D-STEM and EDS for the classification of fine Beta-precipitates in aluminum alloy AA 6063-T6

Tuning the properties of aluminum alloys AA 6063-T6 involves artificial aging to induce precipitate formation, particularly β’’ and β’ phases. Previous characterization challenges due to their similar appearance are addressed here by correlating 4D scanning transmission electron microscopy (4DSTEM) and energy-dispersive spectroscopy (EDS) mapping. This approach allows us to analyze the structure and composition of precipitates individually, overcoming limitations of conventional imaging and structural analysis techniques when the precipitates appear simultaneously, as is often the case. We present detailed characterizations of needle-shaped Beta precipitates, revealing distinct diffraction patterns (DPs) and compositional differences. The method's applicability extends beyond aluminum alloys, offering a promising strategy for complex composite material characterization with multimodal scanning transmission electron microscopy (STEM) techniques.

Synthesis, characterization, and a comparative study on the catalytic activity of the functionalized magnetic nanoparticles for the green oxidation of sulfides

AbstractIn the following research, meso‐tetrakis(4‐carboxyphenyl)porphyrinatomanganese (III) acetate (MnTCPP(OAc)) was immobilized onto the surface of two functionalized magnetic nanoparticles (MNPs) with different linker length via amide bond (Fe3O4@SiO2‐NH2‐MnTCPP(OAc) (A1) and Fe3O4@SiO2‐NHCO‐NH2‐MnTCPP(OAc) (A2)). The prepared catalysts were characterized by standard methods such as: atomic absorption spectroscopy (AAS), Ultra violet‐visible (UV‐Vis), Fourier‐transform infrared (FT‐IR), vibrating sample magnetometry (VSM), field emission scanning electron microscopy (FE‐SEM) and transmission electron microscopy (TEM) techniques and also the effect of the length of the linker on the catalytic activity of supported magnetic nanohybrids was investigated. The prepared magnetic nano‐catalysts with different linker lengths were participated in a comparative study of the clean oxidation of sulfides with urea hydrogen peroxide (UHP) in ethanol. The higher catalytic activity, selectivity and also reusability were achieved in the presence of the catalyst with longer linker length (A2) at ambient temperature. Moreover, the turnover number (TON) of catalytic reactions using A2 as catalyst was highly enough to consider the catalyst as an efficient material to oxidize various sulfides. Both A1 and A2 catalysts simply have accomplished 5 runs of recycling without significant decrease in the catalytic activity.

Atomic-scale investigation on the evolution of T1 precipitates in an aged Al-Cu-Li-Mg-Ag alloy

The T1 (Al2CuLi) phase is one of the most effective strengthening nanoscale-precipitate in Al-Cu alloys with Li. However, its formation and evolution still need to be further clarified during aging due to the complex precipitation sequences. Here, a detailed investigation has been carried out on the atomic structural evolution of T1 precipitate in an aged Al-Cu-Li-Mg-Ag alloy using state-of-the-art Cs-corrected high-angle annular dark field (HAADF)- coupled with integrated differential phase contrast (iDPC)-scanning transmission electron microscopy (STEM) and energy-dispersive X-ray spectroscopy (EDXS) techniques. An intermediate T1’ phase between T1p and T1 phase, with a crystal structure and orientation relationship consistent with T1, but exhibiting different atomic occupancy and chemical composition was found. We observed the atomic structural transformation from T1p to T1’ phase (fcc→hcp), involving only 1/12<112>Al shear component. DFT calculation results validated our proposed structural models and the precipitation sequence. Besides, the distributions of minor solute elements (Ag, Mg, and Zn) in the precipitates exhibited significant differences. These findings may contribute to a further understanding of the nucleation mechanism of T1 precipitate.

Role of grain interface on dielectric and multiferroic properties of 0-3 type (x)CoFe2O4–(1−x)Ba0.8Sr0.2TiO3 nanocomposites

The (x)CoFe2O4–(1−x)Ba0.8Sr0.2TiO3 (0-3 type particulate) nanocomposites with x = 0.00, 0.02, 0.04, 0.06, 0.08, and 1.00 were prepared by the solid-state method. Cobalt ferrite crystallized into cubic crystal symmetry with an Fd3̄m space group. Strontium-substituted barium titanate crystallized into a tetragonal crystal structure with a P4mm space group. Field emission scanning electron microscopy and transmission electron microscopy techniques show the distribution of different sizes of particle. Polarization vs electric field curves show the highest maximum polarization (Pm) of 10.26 μC/cm2, remnant magnetization (Pr) of 11.70 μC/cm2, and coercivity (Ec) of 19.95 kV/cm for x = 0.04 composition at 35 kV/cm. However, it is smaller than the Ba0.8Sr0.2TiO3 phase (Pm = 16.86 μC/cm2, Pr = 13.20 μC/cm2, and EC = 10.80 kV/cm). The highest dielectric constant of around 9800 was found for x = 0.04 composition, with a very small dielectric loss factor of about 0.02, i.e., less than even 2%. This is ∼10 times compared to that of Ba0.8Sr0.2TiO3 (BSTO), which has been explained by considering interaction at the interface of CoFe2O4 (CFO) and BSTO, leakage current, and variation of the lattice parameter of BSTO in (x)CoFe2O4–(1−x)Ba0.8Sr0.2TiO3 nanocomposite. The magnetic hysteresis loops show squeezing near the origin. The magnetic parameters like coercivity, remnant magnetization, and saturation magnetization increased with the increase in the CoFe2O4 weight fraction. Magnetic interaction between surfaces of magnetic CFO and non-magnetic BSTO is evident from the ΔH vs M plots, and it also evidences the magnetism at the surface of BSTO due to uncompensated spins.

Suppressing Metal Leaching and Sintering in Hydroformylation Reaction by Modulating the Coordination of Rh Single Atoms with Reactants.

Hydroformylation reaction is one of the largest homogeneously catalyzed industrial processes yet suffers from difficulty and high cost in catalyst separation and recovery. Heterogeneous single-atom catalysts (SACs), on the other hand, have emerged as a promising alternative due to their high initial activity and reasonable regioselectivity. Nevertheless, the stability of SACs against metal aggregation and leaching during the reaction has rarely been addressed. Herein, we elucidate the mechanism of Rh aggregation and leaching by investigating the structural evolution of Rh1@silicalite-1 SAC in response to different adsorbates (CO, H2, alkene, and aldehydes) by using diffuse reflectance infrared Fourier transform spectroscopy, X-ray adsorption fine structure, and scanning transmission electron microscopy techniques and kinetic studies. It is discovered that the aggregation and leaching of Rh are induced by the strong adsorption of CO and aldehydes on Rh, as well as the reduction of Rh3+ by CO/H2 which weakens the binding of Rh with support. In contrast, alkene effectively counteracts this effect by the competitive adsorption on Rh atoms with CO/aldehyde, and the disintegration of Rh clusters. Based on these results, we propose a strategy to conduct the reaction under conditions of high alkene concentration, which proves to be able to stabilize Rh single atom against aggregation and/or leaching for more than 100 h time-on-stream.

Thermoelectric Limitations of Graphene Nanodevices at Ultrahigh Current Densities.

Graphene is atomically thin, possesses excellent thermal conductivity, and is able to withstand high current densities, making it attractive for many nanoscale applications such as field-effect transistors, interconnects, and thermal management layers. Enabling integration of graphene into such devices requires nanostructuring, which can have a drastic impact on the self-heating properties, in particular at high current densities. Here, we use a combination of scanning thermal microscopy, finite element thermal analysis, and operando scanning transmission electron microscopy techniques to observe prototype graphene devices in operation and gain a deeper understanding of the role of geometry and interfaces during high current density operation. We find that Peltier effects significantly influence the operational limit due to local electrical and thermal interfacial effects, causing asymmetric temperature distribution in the device. Thus, our results indicate that a proper understanding and design of graphene devices must include consideration of the surrounding materials, interfaces, and geometry. Leveraging these aspects provides opportunities for engineered extreme operation devices.

The inhibition effects of Lentilactobacillus buchneri-derived membrane vesicles on AGS and HT-29 cancer cells by inducing cell apoptosis

In recent years, probiotics and their derivatives have been recognized as important therapeutic agents in the fight against cancer. Therefore, this study aimed to investigate the anticancer effects of membrane vesicles (MVs) from Lentilactobacillus buchneri strain HBUM07105 probiotic isolated from conventional and unprocessed yogurt in Arak province, Iran, against gastric and colon cancer cell lines. The MVs were prepared from the cell-free supernatant (CFS) of L. buchneri and characterized using field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) and SPS-PAGE techniques. The anticancer activity of MVs was evaluated using MTT, flow cytometry, qRT-PCR techniques, and a scratch assay. The study investigated the anti-adenocarcinoma effect of MVs isolated from L. buchneri on a human gastric adenocarcinoma cell line (AGS) and a human colorectal adenocarcinoma cell line (HT-29) at 24, 48, and 72-h time intervals. The results demonstrated that all prepared concentrations (12.5, 25, 50, 100, and 200 µg/mL) of MVs reduced the viability of both types of human adenocarcinoma cells after 24, 48, and 72 h of treatment. The analysis of the apoptosis results revealed that the percentage of AGS and HT-29 cancer cells in the early and late stages of apoptosis was significantly higher after 24, 48, and 72 h of treatment compared to the untreated cancer cells. After treating both AGS and HT-29 cells with the MVs, the cells were arrested in the G0/G1 phase. These microvesicles demonstrate apoptotic activity by increasing the expression of pro-apoptotic genes (BAX, CASP3, and CASP9). According to the scratch test, MVs can significantly decrease the migration of HT-29 and AGS cancer cells after 24, 48, and 72 h of incubation compared to the control groups. The MVs of L. buchneri can also be considered a potential option for inhibiting cancer cell activities.

Quantitative Scanning Transmission Electron Microscopy–High‐Angle‐Annular Dark‐Field Study of the Structure of Pseudo‐2D Sb2Te3 Films Grown by (Quasi) Van der Waals Epitaxy

Scanning transmission electron microscopy (STEM) techniques are used to improve the understanding of out‐of‐plane oriented Sb2Te3 thin films deposited by sputtering on SiO2 and Si substrates. Nanobeam precession electron diffraction, energy‐dispersive X‐ray spectroscopy, and high‐angle‐annular dark‐field imaging show that the presence of 1–2 atomic planes of Te on top of the substrate is a crucial factor for successful growth of such films, which can be achieved by optimizing cosputtering of Te and Sb2Te3 targets. The formation of an actual van der Waals (vdW) gap between the substrate and the first Sb2Te3 quintuple layer allows for vdW epitaxy. This gap is larger than those separating Te planes in the pseudo‐2D Sb2Te3 structure. HAADF image analysis provides detailed information on the atomic arrangement such as interplanar distances, vdW gaps, and Debye–Waller coefficients, all these with a few pm precision. For the anisotropic atomic displacements, a new methodology is introduced based on the statistical analysis of atomic column positions that provides information on the low‐frequency phonon modes. Ab initio calculations are used to support our results. Overall, this study provides quantitative STEM tools particularly well suited for nonperiodic pseudo‐2D materials, such as Sb2Te3/GeTe superlattices.

Investigation of nanoscale strain fields induced by the L12–Al3Zr phase in Al–Zn–Mg–Cu alloys

Al–Zn–Mg–Cu alloys are widely used in aerospace as an advanced lightweight structural material. The precipitation of the nanoscale L12–Al3Zr phase enhances the mechanical properties of the alloy. This study employs scanning transmission electron microscopy and geometric phase analysis techniques to investigate the strain fields induced by the nanoscale L12–Al3Zr phase. The findings demonstrate that after the precipitation of the L12–Al3Zr phase, the strain within the L12–Al3Zr phase is negligible, and a coherent strain field is developed near the L12–Al3Zr/Al interface. Characterizing the coherent strain fields of the nanoscale L12–Al3Zr phase provides a valuable reference for optimizing the mechanical properties of Al alloys.

Formation and properties of spindle-shaped aragonite mesocrystals from Mg-bearing solutions.

The formation of aragonite under ambient conditions is typically linked to Mg-rich aqueous environments. The grains that form in such environments show peculiar properties such as aggregate-like appearance and mesocrystalline character. We tested the effect of dissolved Mg2+ ions on the formation of aragonite mesocrystals by synthesizing aragonite with an automatic titrator at constant pH and at different dissolved Mg : Ca ratios, and by studying the properties of the precipitated material with various scanning transmission electron microscopy (STEM) techniques. At all studied Mg : Ca ratios the firstly condensed carbonate phase was Mg-bearing amorphous calcium carbonate (Mg-ACC) that transformed into aragonite during the synthesis experiments. The aragonite grains had typically aggregate-like appearance and spindle shapes, with the external morphologies of the spindles unaffected by variation in solution chemistry. The alignment of the nanocrystals within the aggregates was crystallographically highly coherent, the [001] directions of nanocrystals showing only a small misorientation with respect to one another; however, both parallel and twin assembly of neighbouring crystals occurred. An increase in the dissolved Mg concentration decreased the crystallographic coherence between the aragonite nanocrystals, suggesting an important role of Mg2+ ions in the assembly of aragonite spindles. Whereas the mesoscale-ordered arrangement of nanocrystals implies a particle-mediated assembly, the observed differences in particle size and composition between the amorphous precursor and the crystalline end-product suggest that the crystallization includes at least partial dissolution and re-precipitation. These findings provide insight into the formation of aragonite and could contribute to the understanding of important aspects of the formation of mesocrystals and hierarchically structured biogenic minerals.

Electrodeposited alloy electrodes in the Co–W–Mo system as highly efficient catalysts for hydrogen production from alkaline water electrolysis

In the presented paper the non-precious electrode materials containing Co, Mo, and W demonstrating high catalytic activity towards hydrogen evolution reaction were characterized. The studied alloy electrodes were electrodeposited from electrolytes with a simple composition, containing CoSO4, Na2WO4, Na2MoO4, and Na3C6H5O7. The structure, surface morphology, and composition of the prepared deposits were analyzed using scanning microscopy, X-ray diffraction, and transmission electron microscopy techniques. Cathodic polarization and electrochemical impedance spectroscopy were applied to assess the electrocatalytic activity and elucidate the HER mechanism in 1 M KOH solution. The nanocrystalline structure, fine grain size, and presence of microcracks on the surface of the studied alloys contributed to their notably high electrochemically active surface area (ECSA) (65.7e2, 11.7e4, and 99.7e3 cm2 for the Co–W, Co–Mo, and Co–W–Mo, respectively), a crucial factor driving their superior catalytic activity. The intrinsic catalytic activity evaluated at the overpotential of 150 mV was 9.2, 3.3, 0.78 and 1.4 μA cm-2 for the Co, Co–W, Co–Mo and Co–W–Mo electrodes, respectively. This indicates that the superior electrocatalytic characteristics observed for the alloy coatings, compared to Co resulted from the substantial increase in their ECSA. Among the investigated electrodes, the ternary Co–W–Mo alloy was characterized by the highest electrocatalytic performance confirmed by the lowest overpotential (42 mV) required to attain a current density of 10 mA cm−2.

Cellulose beads supported CoFe2O4: A novel heterogeneous catalyst for efficient rhodamine B degradation via advanced oxidation processes

In this study, a novel mechanical process was used to produce cellulose beads (CB). These beads were then doped with cobalt ferrite nanoparticles (CoFe2O4 NPs) to serve as catalysts for the degradation of rhodamine B (RhB) through peroxymonosulfate (PMS) activation. The physical and chemical properties of CoFe2O4 and CoFe2O4@CB catalysts were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) combined with energy dispersive X-ray spectrometer (EDX), scanning transmission electron microscopy (STEM) techniques, and thermogravimetric analysis (TGA). To optimize RhB degradation efficiency, Response Surface Methodology (RSM) was employed, utilizing the Box-Behnken design (BBD). Under the optimized conditions of a catalyst dosage of 0.40 g/L, PMS dosage of 0.98 mM, RhB concentration of 40 mg/L, pH of 5.27, and reaction time of 60 min, a remarkable degradation efficiency of 98.51 % was achieved at a temperature of 25 °C. In quenching experiments, 1O2, SO4•−, and HO• species are produced in the CoFe2O4@CB/PMS system, with 1O2, and SO4•− species dominating RhB degradation. Remarkably, the new CoFe2O4@CB catalyst has demonstrated exceptional stability and reusability, validated by recycling tests (up to 78 % of RhB degradation efficiency after a 5-cycle experiment) and subsequent characterizations (FTIR, SEM, and EDX) emphasizing unchanged bands, uniform distribution, and consistent composition after reuse cycles. These results demonstrate the effectiveness of mechanically produced CoFe2O4@CB catalysts for advanced oxidation processes (AOPs), with promising applications in wastewater treatment.

Probing Oxidation-Driven Amorphized Surfaces in a Ta(110) Film for Superconducting Qubit.

Recent advances in superconducting qubit technology have led to significant progress in quantum computing, but the challenge of achieving a long coherence time remains. Despite the excellent lifetime performance that tantalum (Ta) based qubits have demonstrated to date, the majority of superconducting qubit systems, including Ta-based qubits, are generally believed to have uncontrolled surface oxidation as the primary source of the two-level system loss in two-dimensional transmon qubits. Therefore, atomic-scale insight into the surface oxidation process is needed to make progress toward a practical quantum processor. In this study, the surface oxidation mechanism of native Ta films and its potential impact on the lifetime of superconducting qubits were investigated using advanced scanning transmission electron microscopy (STEM) techniques combined with density functional theory calculations. The results suggest an atomistic model of the oxidized Ta(110) surface, showing that oxygen atoms tend to penetrate the Ta surface and accumulate between the two outermost Ta atomic planes; oxygen accumulation at the level exceeding a 1:1 O/Ta ratio drives disordering and, eventually, the formation of an amorphous Ta2O5 phase. In addition, we discuss how the formation of a noninsulating ordered TaO1-δ (δ < 0.1) suboxide layer could further contribute to the losses of superconducting qubits. Subsurface oxidation leads to charge redistribution and electric polarization, potentially causing quasiparticle loss and decreased current-carrying capacity, thus affecting superconducting qubit coherence. The findings enhance the comprehension of the realistic factors that might influence the performance of superconducting qubits, thus providing valuable guidance for the development of future quantum computing hardware.

Translational Antiphase Boundaries in NaNbO3 Antiferroelectrics.

Planar defects are known to be of importance in affecting the functional properties of materials. Translational antiphase boundaries (APBs) in particular have attracted considerable attention in perovskite oxides, but little is known in lead-free antiferroelectric oxides that are promising candidates for energy storage applications. Here, we present a study of translational APBs in prototypical antiferroelectric NaNbO3 using aberration-corrected (scanning) transmission electron microscopy (TEM) techniques at different length scales. The translational APBs in NaNbO3 are characterized by a 2-fold-modulated structure, which is antipolar in nature and exhibits a high density, different from the polar nature and lower density in PbZrO3. The high stability of translational APBs against external electric fields and elevated temperatures was revealed using ex situ and in situ TEM experiments and is expected to be associated with their antipolar nature. Density functional theory calculations demonstrate that translational APBs possess only slightly higher free energy than the antiferroelectric and ferroelectric phase energies with differences of 29 and 33 meV/f.u., respectively, justifying their coexistence down to the nanoscale at room temperature. These results provide a detailed atomistic elucidation of translational APBs in NaNbO3 with antipolar character and stability against external stimuli, establishing the basis of defect engineering of antiferroelectrics for energy storage devices.

Insight into Crystalline Structure and Physicochemical Properties of Quartz-Carbon Ore

Composites made from carbon and nanominerals show great potential for thermal phase change materials, environmental water treatment, and biomass conversion. In 2019, a micro and nano-quartz-carbon ore was discovered in Feng-cheng City, Jiangxi Province. The study of the structural and physicochemical changes of quartz-carbon ore (QZC) during calcination is essential for the preparation of QZC-based composites and to broaden their application areas. Firstly, the SiO2 crystal structure evolution of QZC during calcination was investigated using in-situ X-ray diffraction (XRD), 29Si magic-angle sample spinning nuclear magnetic resonance (MAS NMR), and Fourier transform infrared FTIR spectroscopy. Then, the changes in carbon during calcination were investigated using Raman spectroscopy, 13C MAS NMR, and X-ray photoelectron spectroscopy (XPS). In addition, changes in the QZC morphology were observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. Finally, the evolution of the physicochemical properties of QZC during calcination was revealed using thermogravimetric (TG), Brunauer–Emmet–Teller (BET), resistivity, thermal conductivity, and zeta potential techniques.

Large bi-axial tensile strain effect in epitaxial BiFeO3 film grown on single crystal PrScO3

A BiFeO3 film is grown epitaxially on a PrScO3 single crystal substrate which imparts ~ 1.45% of biaxial tensile strain to BiFeO3 resulting from lattice misfit. The biaxial tensile strain effect on BiFeO3 is investigated in terms of crystal structure, Poisson ratio, and ferroelectric domain structure. Lattice resolution scanning transmission electron microscopy, precession electron diffraction, and X-ray diffraction results clearly show that in-plane interplanar distance of BiFeO3 is the same as that of PrScO3 with no sign of misfit dislocations, indicating that the biaxial tensile strain caused by lattice mismatch between BiFeO3 and PrScO3 are stored as elastic energy within BiFeO3 film. Nano-beam electron diffraction patterns compared with structure factor calculation found that the BiFeO3 maintains rhombohedral symmetry, i.e., space group of R3c. The pattern analysis also revealed two crystallographically distinguishable domains. Their relations with ferroelectric domain structures in terms of size and spontaneous polarization orientations within the domains are further understood using four-dimensional scanning transmission electron microscopy technique.

Green synthesis of nanohydroxyapatite trough Elaeagnus angustifolia L. extract and evaluating its anti-tumor properties in MCF7 breast cancer cell line

BackgroundOne of the most common types of cancer in women is breast cancer. There are numerous natural plant-based products, which exert anti-tumoral effects including Elaeagnus Angustifolia (EA). It modulates cell-cycle process, heat-shock proteins expression, anti-proliferative properties, apoptosis induction, blocking of angiogenesis, and cell invasion inhibition. The current study aimed to synthesize and evaluate the anticancer effects of hydroalcoholic EA extract (HEAE), Nanohydroxyapatite (nHAp) and nHAp synthesized trough EA (nHA-EA) in MCF-7 breast cancer cell line.MethodsIn the present study, HEAE preparation and green synthesis of nHA-EA was done and phase composition, functional groups, and crystallin phase of nHA-EA and nHAp were determined using Fourier-transform infrared (FTIR) and X-ray diffraction (XRD). The characteristics of synthesized nanoparticles including structural and morphological parameters were investigated using scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) techniques. Then, by using MTT-assay (Dimethylthiazoldiphenyltetrazolium), the in vitro cytotoxic and half maximal inhibitory concentration (IC50) of EA extract, nHAp, and nHA-EA in the MCF-7 breast cancer cell line was evaluated. Next, we assessed the expression of apoptosis-related genes Bax, Bcl2 and p53 using quantitative reverse-transcriptase polymerase-chain-reaction (qRT-PCR) and migration of MCF-7 cells by scratch assay.ResultsThe FTIR results demonstrated formation of nHAp and its interaction with HEAE during synthesis process. The XRD results of the synthesized nanoparticles showed similar XRD pattern of nHA-EA and nHAp and purity of synthesized nanomaterials. The average IC50 of HEAE, nHAp, and nHA-EA extract after treatment of cancer cells for 24 h was 400 µg/mL, 200 µg/mL, and 100 µg/mL, respectively. Our results revealed that nHA-EA significantly reduced the migration and invasion of the MCF-7 cells, in comparison to the nHAp and EA extract. Moreover, level of Bax/Bcl2 and p53 was significantly higher in the nHA-EA extract group in comparison to the EA extract and nHAp group.ConclusionTaken together, our results demonstrated that bioactive constituents of EA medicinal plant in form of nHA-EA particles, can effectively exerts potential anticancer and chemo preventive effect against breast cancer growth and can be proposed as a promising beneficial candidate for BC therapy. However, further investigations are required to discover what bioactive compounds are responsible for the chemo preventive effect of this extract.

A metal-free photoactive nitrogen-doped carbon nanosolenoid with broad absorption in visible region for efficient photocatalysis

Riemann surfaces inspired chemists to design and synthesize such multidimensional curved carbon architectures. It has been predicted that carbon nanosolenoid materials with Riemann surfaces have unique structures and novel physical properties. Here we report the first synthesis of a nitrogen-doped carbon nanosolenoid (N-CNS) using bottom-up approach with a well-defined structure. N-CNS was obtained by a rational Suzuki polymerization, followed by oxidative cyclodehydrogenation. The successful synthesis of N-CNS was fully characterized by GPC, FTIR, solid-state 13C NMR and Raman techniques. The intrinsic single-strand molecular structures of N-CNS helices can be clearly resolved using low-dose integrated differential phase contrast scanning transmission electron microscopy (iDPC-STEM) technique. Possessing unique structural and physical properties, this long π-extended polymer N-CNS can provide new insight towards bottom-up syntheses of curved nanoribbons and potential applications as a metal-free photocatalyst for visible-light-driven H2 evolution and highly efficient photocatalyst for photoredox organic transformations.

Atomically dispersed copper-nickel electrocatalyst for highly selective electroreduction of CO2 at a wide potential range

Designing and synthesising electrocatalysts with low overpotential, high activity, selectivity, and stability for the CO2 reduction reaction (CO2RR) is crucial for addressing environmental challenges and realising the artificial carbon cycle. In this study, we successfully synthesised a nitrogen-doped carbon-supported diatomic electrocatalyst comprising atomically dispersed CuN4 and NiN4 bimetallic centers. This was confirmed through extensive characterisation using high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption spectroscopy techniques. The as-synthesised CBN-CuNi electrocatalyst exhibited exceptional selectivity and stability in CO2RR. Over a wide potential range from − 0.60 to − 1.10 V vs RHE, CBN-CuNi maintained over 90% Faraday efficiency for CO (FECO) production. Notably, at − 0.9 V vs RHE, it achieved a remarkable selectivity with a maximum FECO of 97.9%, surpassing single metal catalysts, including CBN-Ni and CBN-Cu. Furthermore, CBN-CuNi demonstrated outstanding stability, sustaining over 90% FECO production for 40 h of continuous electrolysis, surpassing many existing electrocatalysts. These findings highlight the potential of the as-synthesised bimetallic electrocatalyst CBN-CuNi in the electrochemical reduction of CO2 to CO, contributing to advancing the artificial carbon cycle and addressing environmental concerns.