Metal Precursors Research Articles

Zn Oxide Nanoparticles and Fine Particles: Synthesis, Characterization and Evaluation of the Toxic Effect on Germination and Vigour of Solanum licopersicum L.

The micronutrient Zinc (Zn) is essential for the proper growth and development of crops. Zinc oxide nanoparticles (NPs) and fine particles are presented as an emerging alternative to more traditional fertilizers. In this study, the possible toxic effect of four laboratory-synthesized ZnO NPs and fine particles with different characteristics on tomato seed germination and vigor parameters was examined in comparison to bulk ZnO. Different metal precursors were used for the chemical synthesis of the particles: Zn(NO3)2 and ZnSO4, for particles named NIT-. and SUL-., respectively. In addition, the synthesis process was modified to obtain coated particles (denoted as UW-, NIT-UW and SUL-UW) and washed particles (denoted as W-, NIT-W and SUL-W). These particles were applied at different toxic doses (0, 1.4, 2.8, 5.6 and 11.2 g L−1). The results indicated that although the constant contact time between the ZnO particles did not affect the germination capacity of the seeds, it affected the growth of roots and hypocotyls, with a higher impact on the roots’ development. This toxicity was more evident from the lowest particle dose used, although it did not prevent radicle and hypocotyl elongation during the development period studied (14 days). The synthesized coated particles (NIT-UW, SUL-UW) generated high toxicity on radicle and hypocotyl development, and this effect was observed from the first days of contact with the particles. The observed toxic effects on radicle length were minimized by the application of bulk ZnO particles. In the case of hypocotyl growth, these minor toxic effects were observed by using NIT-W particles and bulk ZnO. The possibility of positive effects on seed germination and development (radicle and hypocotyl length) when in continuous contact with ZnO, whether in fine particles, nanoparticles, or bulk sizes, was excluded. Furthermore, no benefits on germination parameters were observed by suppressing the final washing step in the particle’s synthesis process, suggesting that particle coating did not provide any advantage for seed germination under these continuous contact conditions.

Confined-Coordination Induced Intergrowth of Metal-Organic Frameworks into Precise Molecular Sieving Membranes.

Metal-organic framework (MOF) membranes with rich functionality and tunable pore system are promising for precise molecular separation; however, it remains a challenge to develop defect-free high-connectivity MOF membrane with high water stability owing to uncontrollable nucleation and growth rate during fabrication process. Herein, we report on a confined-coordination induced intergrowth strategy to fabricate lattice-defect-free Zr-MOF membrane towards precise molecular separation. The confined-coordination space properties (size and shape) and environment (water or DMF) were regulated to slow down the coordination reaction rate via controlling the counter-diffusion of MOF precursors (metal cluster and ligand), thereby inter-growing MOF crystals into integrated membrane. The resulting Zr-MOF membrane with angstrom-sized lattice apertures exhibits excellent separation performance both for gas separation and water desalination process. It was achieved H2 permeance of ~1200 GPU and H2/CO2 selectivity of ~67; water permeance of ~8 L ⋅ m-2 ⋅ h-1 ⋅ bar-1 and MgCl2 rejection of ~95 %, which are one to two orders of magnitude higher than those of state-of-the-art membranes. The molecular transport mechanism related to size-sieving effect and transition energy barrier differential of molecules and ions was revealed by density functional theory calculations. Our work provides a facile approach and fundamental insights towards developing precise molecular sieving membranes.

Confined‐Coordination Induced Intergrowth of Metal–Organic Frameworks into Precise Molecular Sieving Membranes

AbstractMetal–organic framework (MOF) membranes with rich functionality and tunable pore system are promising for precise molecular separation; however, it remains a challenge to develop defect‐free high‐connectivity MOF membrane with high water stability owing to uncontrollable nucleation and growth rate during fabrication process. Herein, we report on a confined‐coordination induced intergrowth strategy to fabricate lattice‐defect‐free Zr‐MOF membrane towards precise molecular separation. The confined‐coordination space properties (size and shape) and environment (water or DMF) were regulated to slow down the coordination reaction rate via controlling the counter‐diffusion of MOF precursors (metal cluster and ligand), thereby inter‐growing MOF crystals into integrated membrane. The resulting Zr‐MOF membrane with angstrom‐sized lattice apertures exhibits excellent separation performance both for gas separation and water desalination process. It was achieved H2 permeance of ~1200 GPU and H2/CO2 selectivity of ~67; water permeance of ~8 L ⋅ m−2 ⋅ h−1 ⋅ bar−1 and MgCl2 rejection of ~95 %, which are one to two orders of magnitude higher than those of state‐of‐the‐art membranes. The molecular transport mechanism related to size‐sieving effect and transition energy barrier differential of molecules and ions was revealed by density functional theory calculations. Our work provides a facile approach and fundamental insights towards developing precise molecular sieving membranes.

Green synthesis of copper and iron nanoparticles from extracts of eucalyptus with their antimicrobial activities

Eco-friendly iron and copper nanoparticles were synthesized using masquerade and eucalyptus leaves extract as a reducing and stabilizing agents. Iron chloride heptahydrate (FeCl2.7H2O) and Copper sulphatepenta hydrate (CuSO4.5H2O) as metal precursors. It was characterized using UV visible, FTIR, XRD and SEM analysis. The UV result shows the highest peaks at 500 and 600 nm for iron and copper respectively. This is due to the surface plasma vibration of the phytochemical constituents present in the extract. FTIR shows presence of alkanoids and triterpenes, SEM shows the spherical granular with no well-defined morphology and mono dispersed structures for iron and copper nanoparticles respectively. It shows good antibacterial activity when tested against Escherichia-coli and Pseudomonas auredinosa (gram- negative), Staphylococcus aureus and Klebsella pneumonia (gram-positive).

Generalized Synthesis of Highly-Dispersed, Ultrafine Transition Metal Nanoparticles on Silica Spheres for Enhanced Optical Absorption.

Robust synthesis of ultrafine metal nanoparticles (ufMNPs) below 5nm with clean surfaces and strong optical absorption in the visible spectral range is challenging due to their instability originating from large surface-to-volume ratios. This work reports a general strategy involving two sequential steps: i) loading metal precursor ions onto the surface of silica nanospheres (SiOx NSs) by forming a uniform coating of metal oxyhydroxide [MOy(OH)z] through preferred surface acid-base reactions and ii) thermally reducing MOy(OH)z in forming gas at elevated temperatures to form ufMNPs evenly dispersed on the surface of SiOx NSs. The capability of this synthesis strategy is verified by loading ufMNPs of various transition metals and bimetallic combinations onto the SiOx NSs. The ufMNPs exhibit strong optical absorption enhanced by the optical scattering resonances in the SiOx NSs, which generate intense electric fields near the surface of the SiOx NSs. The SiOx NSs also support stabilizing the ufMNPs, which do not need additional organic capping reagents. The successful synthesis of SiOx-NS-supported ufMNPs with clean surfaces and enhanced optical absorption is promising for exploring the photocatalytic properties of ufMNPs.

Superparamagnetic iron oxide nanoparticles functionalized by biocompatible ligands with enhanced high specific absorption rate for magnetic hyperthermia

This study introduces a novel green nanocomposite system of iron oxide coated with secondary metabolites (Fe3O4@SM) and compares it with commonly used materials for hyperthermia cancer treatment. Fe3O4@SM magnetic nanoparticles were synthesized through a simple co-precipitation process using metal precursors, followed by heating in pressure reactor to obtain superparamagnetic nanoparticles (Hc = 36.5–54.1 Oe at 300 K). These nanoparticles were subsequently coated with plant-based phytochemicals. XRD analysis confirmed the presence of magnetite iron oxide nanoparticles. SEM images further confirmed the spherical shape of the synthesized nanoparticles, exhibiting a face-centered cubic (FCC) iron oxide structure with sizes ranging from 12±7–85±15 nm. Characterization through dynamic light scattering (DLS) and zeta potential (ζ) analysis demonstrated colloidal stability, with a polydispersity index (PDI) ranging from 0.226 to 0.436 and zeta potential values ranging from −29.761–1.85 mV. The surface of the nanoparticles was analyzed using GC-MS, which identified bioactive functional groups including ester (42.79 %), terpene (20.69 %), hydrocarbons (17.4 %), and carboxylic (12.37 %) compounds. Compared to Fe3O4 and Fe3O4@GO, Fe3O4@SM exhibited a higher rate of temperature increase within the therapeutic range, reaching Tmax = 45°C with a heating rate (dT/dt) of 0.273 °C/s and specific absorption rate (SAR) of 230.6 W/g at 304 kHz and 400 Oe. In vitro assays utilizing a triple negative breast cancer microenvironment confirmed the non-toxicity of these materials through a DNS assay. The developed nanoparticles offer dual mechanisms of action, combining thermal and chemo effects, making them promising candidates for hyperthermia cancer treatment.

3D-Continuous Nanoporous Covalent Framework Membrane Nanoreactors with Quantitatively Loaded Ultrafine Pd Nanocatalysts.

The confinement effect of catalytic nanoreactors containing metal catalysts within nanometer-sized volumes has attracted significant attention for their potential to enhance reaction rate and selectivity. Nevertheless, unregulated catalyst loading, aggregation, leaching, and limited reusability remain obstacles to achieving an efficient nanoreactor. A robust and durable catalytic membrane nanoreactor prepared by incorporating palladium nanocatalysts within a 3D-continuous nanoporous covalent framework membrane is presented. The reduction of palladium precursor occurs on the pore surface within 3D nanochannels, producing ultrafine palladium nanoparticles (Pd NPs) with their number density adjustable by varying metal precursor concentrations. The precise catalyst loading enables controlling the catalytic activity of the reactor while preventing excess metal usage. The facile preparation of Pd NP-loaded free-standing membrane materials allows hydrodechlorination in both batch and continuous flow modes. In batch mode, the catalytic activity is proportional to the loaded Pd amount and membrane area, while the membrane retains its activity upon repeated use. In continuous mode, the conversion remains above 95% for over 100h, with the reactant solution passing through a single 50µm-thick Pd-loaded membrane. The efficient nanoporous film-type catalytic nanoreactor may find applications in catalytic reactions for small chemical devices as well as in conventional chemistry and processes.

Lithium Ion Intercalation-Induced Metal-Insulator Transition in Inclined-Standing Grown 2D Non-Layered Cr2S3 Nanosheets.

Gate-controlled ionic intercalation in the van der Waals gap of 2D layered materials can induce novel phases and unlock new properties. However, this strategy is often unsuitable for densely packed 2D non-layered materials. The non-layered rhombohedral Cr2S3 is an intrinsic heterodimensional superlattice with alternating layers of 2D CrS2 and 0D Cr1/3. Here an innovative chemical vapor deposition method is reported, utilizing strategically modified metal precursors to initiate entirely new seed layers, yields ultrathin inclined-standing grown 2D Cr2S3 nanosheets with edge instead of face contact with substrate surfaces, enabling rapid all-dry transfer to other substrates while ensuring high crystal quality. The unconventional ordered vacancy channels within the 0D Cr1/3 layers, as revealed by cross-sectional scanning transmission electron microscope, permitting the insertion of Li+ ions. An unprecedented metal-insulator transition, with a resistance modulation of up to six orders of magnitude at 300 K, is observed in Cr2S3-based ionic field-effect transistors. Theoretical calculations corroborate the metallization induced by Li-ion intercalation. This work sheds light on the understanding of growth mechanism, structure-property correlation and highlights the diverse potential applications of 2D non-layered Cr2S3 superlattice.

Synthesis and characterization of coprecipitated layered NCM oxide as cathode for sodium-ion batteries: Kinetics and hydrodynamics studies

Interest in the development of high-performance sodium-ion batteries (SIBs) as a sustainable alternative to lithium-ion batteries (LIBs) for emerging energy storage systems has motivated to delve into a novel approach for the synthesis of layered transition metal oxide (LTMO) type cathode for SIBs batteries. In this study, we introduce novel chemical synthesis method that diverges from traditional methodologies reported till date. Rather than relying on sulfur, nitrate, or acetate metal precursor salts, we employ metal carbonate salt coupled with oxalic acid as a chelating agent, and sodium carbonate as a precipitating agent. This novel chemistry enhances the microstructure of the cathode material inherited from its precursor exhibiting spherical morphology, influence on the electrochemical properties, bestowing the material with high specific capacity, extended cycle life, and an elevated charge–discharge rate. The primary focus of this work centers on a comprehensive investigation of the hydrodynamic and kinetics aspects of the co-precipitation reaction, guided by the principles of chemical engineering. The effects of key parameters such as impeller speed, impeller type, and scale-up effects on the co-precipitation process have been systematically explored. This research introduces insights into optimizing reaction conditions such as pH, reaction temperature, metal precursor salt ratio, precipitating agent, through rigorous experimentation and characterization reports. The notable effect of precipitating agent on morphology has been demonstrated by electron microscopy images. The kinetics study shows the activation energy of 8.9 kJ mol−1 depicts the reaction is controlled by mass transfer resistance and to overcome this effect, impeller type and speed plays significant role and experimentation results shows the axial mixing pattern created by pitched blade impeller is effective to improvise electrochemical properties. The synthesized cathode material exhibits remarkable electrochemical properties, including tap density of approximately 1.3 g cc−1 with reversible capacity of 215 mAh g−1, along with excellent cyclic stability (90 %) over 60 cycles. Furthermore, it shows the high energy density up to 1300 Wh/L and a rapid charge–discharge rate. These findings contribute to the advancement of SIBs technology and offer promising prospects for future researchers to efficient development of high-performance energy storage solutions.

Electrosynthesis of nitrate by FeS2-TiO2 heterogeneous nanoparticles supported on 2-methylimidazolium functionalized polypyrrole/graphene oxide

Electrochemical nitrogen oxidation reaction (NOR) acts as a clean and sustainable approach for promisingly replacing the conventional industrial method for producing nitrate. Designing and preparing the effective electrocatalysts for NOR has aroused great research interests. Herein, FeS2-TiO2 heterostructures are well-dispersed on the surface of 2-methylimidazolium functionalized polypyrrole/graphene oxide (2-MeIm/PPy/GO) by the in situ growth due to the ion-exchange and the coordination between the 2-MeIm groups and the metal precursors, which exhibit the excellent NOR electroactivity. The highest NO3– yield by the obtained FeS2-TiO2@2-MeIm/PPy/GO reaches to 137.04 μg h−1 mg-1act. with the maximum Faradic efficiency (FE) of 4.38 % at 2.04 V (vs. RHE), better than most reported electrocatalysts. The good selectivity for producing nitrate is also achieved, but the stability of both the NO3– yield and FE present a trend of rising and then declining in the cyclic test of FeS2-TiO2@2-MeIm/PPy/GO. The irreversible conversion of the electrocatalysts can be confirmed through detailed characterization towards the crystal structures and chemical states of FeS2-TiO2@2-MeIm/PPy/GO after long term NOR test. The electrochemical step of NOR mainly occurs at FeS2, converting the inert N2 to active *NO intermediates. SO42- generated at high NOR potential gradually increase by the oxidation of S element, which can cause the promotion of the NOR performance before the fourth cycle. But along with the disappearance of FeS2 phase, FeS2-TiO2 as the catalytic center is finally irreversibly converted to Fe and S ions doped TiO2, resulting in the sharp drop of both the NO3– yield and FE at the sixth cycle. This work will provide valuable guidance for the designing and preparing NOR electrocatalysts.

Breaking Barriers in Eco-Friendly Synthesis of Plant-Mediated Metal/Metal Oxide/Bimetallic Nanoparticles: Antibacterial, Anticancer, Mechanism Elucidation, and Versatile Utilizations

Nanotechnology has emerged as a promising field in pharmaceutical research, involving producing unique nanoscale materials with sizes up to 100 nm via physiochemical and biological approaches. Nowadays more emphasis has been given to eco-friendly techniques for developing nanomaterials to enhance their biological applications and minimize health and environmental risks. With the help of green nanotechnology, a wide range of green metal, metal oxide, and bimetallic nanoparticles with distinct chemical compositions, sizes, and morphologies have been manufactured which are safe, economical, and environment friendly. Due to their biocompatibility and vast potential in biomedical (antibacterial, anticancer, antiviral, analgesic, anticoagulant, biofilm inhibitory activity) and in other fields such as (nanofertilizers, fermentative, food, and bioethanol production, construction field), green metal nanoparticles have garnered significant interest worldwide. The metal precursors combined with natural extracts such as plants, algae, fungi, and bacteria to get potent novel metal, metal oxide, and bimetallic nanoparticles such as Ag, Au, Co, Cu, Fe, Zr, Zn, Ni, Pt, Mg, Ti, Pd, Cd, Bi2O3, CeO2, Co3O4, CoFe2O4, CuO, Fe2O3, MgO, NiO, TiO2, ZnO, ZrO2, Ag-Au, Ag-Cr, Ag-Cu, Ag-Zn, Ag-CeO2, Ag-CuO, Ag-SeO2, Ag-TiO2, Ag-ZnO, Cu-Ag, Cu-Mg, Cu-Ni, Pd-Pt, Pt-Ag, ZnO-CuO, ZnO-SeO, ZnO-Se, Se-Zr, and Co-Bi2O3. These plant-mediated green nanoparticles possess excellent antibacterial and anticancer activity when tested against several microorganisms and cancer cell lines. Plants contain essential phytoconstituents (polyphenols, flavonoids, terpenoids, glycosides, alkaloids, etc.) compared to other natural sources (bacteria, fungi, and algae) in higher concentration that play a vital role in the development of green metal, metal oxide, and bimetallic nanoparticles because these plant-phytoconstituents act as a reducing, stabilizing, and capping agent and helps in the development of green nanoparticles. After concluding all these findings, this review has been designed for the first time in such a way that it imparts satisfactory knowledge about the antibacterial and anticancer activity of plant-mediated green metal, metal oxide, and bimetallic nanoparticles together, along with antibacterial and anticancer mechanisms. Additionally, it provides information about characterization techniques (UV–vis, FT-IR, DLS, XRD, SEM, TEM, BET, AFM) employed for plant-mediated nanoparticles, biomedical applications, and their role in other industries. Hence, this review provides information about the antibacterial and anticancer activity of various types of plant-mediated green metal, metal oxide, and bimetallic nanoparticles and their versatile application in diverse fields which is not covered in other pieces of literature.

Antimicrobial Properties and Cytotoxicity of Iron Oxide Nanoparticles Synthesized Using Melia azedarach Leaf Extract Against Diarrhoeal Pathogens

AbstractThe high mortality and morbidity resulting from an increasing incidence of antibiotic resistance among pathogens highlight a crucial need for the development of novel alternative therapy. In the quest for alternative therapy, this study was conducted to synthesise nanoparticles (NPs) from ferric chloride hexahydrate (FeCl3.6H2O) via Melia azedarach L. (Meliaceae) leaf extract and evaluate their antibacterial properties against multidrug resistant pathogenic Escherichia coli, Salmonella enterica, and Vibrio cholerae. Multidrug-resistant pathogenic bacteria were isolated from cattle faeces and characterised by whole genome sequence analysis. The extracts from M. azedarach leaves were used as reducing, capping, and stabilising agents on the precursor metal (FeCl3.6H2O) to produce NPs. The biosynthesised NPs were characterised by ultraviolent visible (UV–vis) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectrophotometry (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The NPs were tested against multidrug-resistant bacteria to determine the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and rate of kill. In this study, WGS analysis confirmed the bacteria (E. coli, V. cholerae, and S. enterica) isolates to be multidrug-resistant pathogen and NP that has a spherical shape with an average particle size of 49.75 nm was successfully biosynthesised. The NPs displayed significant antimicrobial activities with MIC of 62, 31, and 62 mg/mL, MBC of 500, 250, and 500 µg/mL, and the lowest killing times of 4, 2, and 3 h against E. coli, V. cholerae, and S. enterica, respectively. Interestingly, the concentrations of the NPs required to inhibit the growth of E. coli, V. cholerae, and S. enterica were not toxic to HEK293 cells. Based on the promising antimicrobial activities of the biosynthesised NPs in this study, they could be useful in important therapeutic applications aimed at combating multidrug-resistant pathogens.

Controlled Synthesis of Preferential Facet-Exposed Fe-MOFs for Ultrasensitive Detection of Peroxides.

Exposing different facets on metal-organic frameworks (MOFs) is highly desirable to enhance the performance for various applications, however, exploiting a concise and effective approach to achieve facet-controlled synthesis of MOFs remains challenging. Here, by modulating the ratio of metal precursors to ligands, the facet-engineered iron-based MOFs (Fe-MOFs) exhibits enhanced catalytic activity for Fenton reaction are explored, and the mechanism of facet-dependent performance is revealed in detail. Fully exposed (101) and (100) facets on spindle-shaped Fe-MOFs enable rapid oxidation of colorless o-phenylenediamine (OPD) to colored products, thereby establishing a dual-mode platform for the detection of hydrogen peroxide (H2O2) and triacetone triperoxide (TATP). Thus, a detection limit as low as 2.06nm is achieved, and robust selectivity against a wide range of common substances (>16 types) is obtained, which is further improved by incorporating a deep learning architecture with an SE-VGG16 network model, enabling precise differentiation of oxidizing agents from captured images. The present strategy is expected will shine light on both the rational synthesis of nanomaterials with modulated morphologies and the exploitation of high-performance trace chemical sensors.

Scalable One-Pot Fabrication of Carbon-Nanofiber-Supported Noble-Metal-Free Nanocrystals for Synergetic-Dependent Green Hydrogen Production: Unraveling Electrolyte and Support Effects.

Electrocatalytic hydrogen evolution reactions (HER) are envisaged as the most promising sustainable approach for green hydrogen production. However, the considerably high cost often associated with such reactions, particularly upon scale-up, poses a daunting challenge. Herein, a facile, effective, and environmentally benign one-pot scalable approach is developed to fabricate MnM (M═Co, Cu, Ni, and Fe) nanocrystals supported over in situ formed carbon nanofibers (MnM/C) as efficient noble-metal-free electrocatalysts for HER. The formation of carbon nanofibers entails impregnating cellulose in an aqueous solution of metal precursors, followed by annealing the mixture at 550 °C. During the impregnation process, cellulose acts as a reactor for inducing the in situ reductions of MnM salts with the assistance of ether and hydroxyl groups to drive the mass production (several grams) of ultralong (5 ± 1 μM) carbon nanofibers ornamented with MnM nanoparticles (10-14 nm in size) at an average loading of 2.87 wt %. For better electrocatalytic HER benchmarking, the fabricated catalysts were tested over different working electrodes, i.e., carbon paper, carbon foam, and glassy carbon, in the presence of different electrolytes. All the fabricated MnM/C catalysts have demonstrated an appealing synergetic-effect-dependent HER activity, with MnCo/C exhibiting the best performance over carbon foam, close to that of the state-of-the-art commercial Pt/C (10 wt % Pt), with an overpotential of 11 mV at 10 mA cm-2, a hydrogen production rate of 2448 mol g-1 h-1, and a prolonged stability of 2 weeks. The HER performance attained by MnCo/C nanofibers is among the highest reported for Pt-free electrocatalysts, thanks to the mutual alloying effect, higher synergism, large surface area, and active interfacial interactions over the nanofibers. The presented findings underline the potential of our approach for the large-scale production of cost-effective electrocatalysts for practical HER.

Colloidal Atomic Layer Deposition on Nanocrystals Using Ligand-Modified Precursors.

Atomic layer deposition (ALD) is a method to grow thin metal oxide layers on a variety of materials for applications spanning from electronics to catalysis. Extending ALD to colloidally stable nanocrystals promises to combine the benefits of thin metal oxide coatings with the solution processability of the nanocrystals. However, challenges persist in applying this method, which relate to finding precursors that promote the growth of the metal oxide while preserving colloidal stability throughout the process. Herein, we introduce a colloidal ALD method to coat nanocrystals with amorphous metal oxide shells using metal and oxygen precursors that act as colloidal stabilizing ligands. Our scheme involves metal-amide precursors modified with solubilizing groups and oleic acid as the oxygen source. The growth of the oxide is self-limiting and proceeds in a layer-by-layer fashion. Our protocol is generalizable and intrinsically scalable. Potential applications in display, light detection, and catalysis are envisioned.

In situ assembly FeS2-tetrathiomolybdate nanosheets for imaging-guided tumor vascular collapse and amplified catalytic therapy

Catalytic therapy has recently gained considerable attention as a novel tumor microenvironment (TME)-responsive treatment. While conventional nano-catalysts have demonstrated the ability to induce the death of tumor cells through oxidative damage via the generation of reactive oxygen species (ROS), their therapeutic efficacy is impeded by several factors, including limited tissue penetration depth and suboptimal catalytic efficiency. Herein, the FeS2-tetrathiomolybdate (FeS2-TTM) nanosheet was synthesized via in-situ self-assembled in the specific redox TME using metal precursors of divalent iron and tetrathiomolybdate, and these metal precursors could easily enter tumor cells through vascular penetration to avoid the blood-brain barrier. This nanosheet has been proved to possess peroxidase (POD)-like catalytic activity, which overcomes the limitations of traditional nanoparticals by the bimetallic electron transfer effect in the TME to amplify the catalytic treatment effect. Importantly, it retains the chelating copper characteristics of TTM, and inhibits tumor angiogenesis by depriving the necessary copper in cells and angiogenesis, resulting in vascular embolization to cause tumor blood vessels to collapse. Additionally, it can also act as a nanoprobe that supports both real-time fluorescence imaging monitoring and T1/T2 dual-modality magnetic resonance imaging (MRI). As a promising nanomaterial, this new type of in-situ self-assembled nanosheet provides more varieties for the construction of an integrative platform of tumor diagnosis and treatment.

Metallogeny and Mineral Exploration – Some Personal Reminiscences

The following personalised narrative aims to document the highlights of my involvement in some of the ground breaking developments in Economic Geology and their direct application to mineral exploration and discovery over the past half century. The story begins with my introduction to geology at secondary school and university, followed by doctoral research based on fieldwork in the Andes of South America. Then, as an employee of the Chilean Geological Survey, I got my introduction to porphyry copper deposits before returning to the UK to take up a post-doctoral research fellowship. This formative period concluded with my starting out as an independent geological consultant to the global exploration and mining industry. These early years happened to coincide with the plate tectonics revolution and its radical implications for metallogeny. I realised that porphyry copper and related deposits are integral parts of volcano-plutonic arcs generated during subduction of oceanic lithosphere, and volcanogenic massive sulphide deposits in ophiolite complexes must have formed at oceanic spreading centres. At approximately the same time, application of K-Ar dating to copper deposits led to definition of metallogenic belts and corresponding epochs in the Andes, and then established the timing of their economically important supergene oxidation and enrichment. Subsequently, using more modern and precise U-Pb zircon and Re-Os molybdenite methods, collaborative attempts were made to determine porphyry copper deposit lifespans and ages of various copper belts, deposits and prospects around the world, including the Zambian Copperbelt. The focus on porphyry copper deposits led first to an appreciation of the linkage between them and subaerial volcanism and the importance of potassic alteration as a major host of hypogene copper mineralisation, and then to geological characterisation of the increasing number of gold-rich examples. Appreciation of the importance of hydrothermal breccias in porphyry copper deposits, including recognition of mineralised diatremes, resulted in a classification scheme for breccias that may be extended to related deposit types. Extensive fieldwork showed that zones of advanced argillic alteration, termed lithocaps, constitute the shallow parts of porphyry copper systems. The role of tectonic uplift in both porphyry copper formation and subsequent supergene modification was also charted. The end result of this body of work was a porphyry copper model that can be used as a basic exploration guide. In response to a marked increase in the world gold price in the late 1970s, more effort was devoted to gold concentrations in magmatic arc terranes, commencing with epithermal gold deposits in the shallow lithocaps of porphyry copper systems. This led to an input to classification schemes for epithermal precious metal deposits and, eventually, to assignment of the three main epithermal types to specific tectono-magmatic settings. After years of speculation, porphyry gold deposits were recognised for the first time in northern Chile, followed by definition of a new gold deposit class in association with relatively reduced granitic intrusions. A magmatic-hydrothermal origin for Carlin-type gold deposits was steadfastly supported over many years, notwithstanding its unpopularity until relatively recently, culminating in a proposal for modern analogues. For decades, metallogenic provinces and corresponding epochs have been widely appreciated, but debate concerning their origin(s) persists. The nature of accompanying magmatism could well provide an adequate explanation for at least some provinces (e.g., tin, molybdenum and possibly silver), but precursor metal enrichment in the lowermost crust and/or subcontinental lithospheric mantle may well be required in the case of gold and copper provinces. The story concludes with brief commentary on mineral exploration, which has been my lifelong (pre)occupation. Requirements for success in mineral exploration are discussed, based primarily on familiarity with the circum-Pacific region, followed by analysis of the types of companies and individuals involved and the burgeoning challenges to the exploration process, which, if not remedied, will have dire consequences for future metal production and global plans for the energy transition. My involvement as a lone practitioner in both mineral exploration and metallogenic research probably says something about my independent character traits, but nonetheless has been largely unstructured and certainly unplanned. I have no hesitation in recommending a similar career path for any recent graduate who relishes adventure and is prepared to endure significant work-life imbalance.

Photocatalytic Degradation and Anticancer Activity of Green Synthesized Molybdenum Nanoparticles for Inhibiting the Cervical Cancer Cells

This work reports the synthesis of molybdenum nanoparticles (Mo NPs) through green routes using horse gram seed extracts and characterized by GC-MS, electronic (UV-visible) spectroscopy, IR, XRD and SEM techniques. Their potent applications as in vitro anticancer agent against HeLa cell lines and photocatalytic degradation of methyl orange (MO) and methyl violet (MV) dyes were also evaluated. The anti-malignant properties of Schiff base ligands [2-fluorobenzaldehyde semicarbazone (L1H) and 2-fluorobenzaldehyde thiosemicarbazone (L2H) with molybdenum metal precursor [dioxobis(2,4-pentanedionato)molybdenum] were also explored and their Mo complexes after conversion into nano form as both ligands, L1H and L2H approve their binding property based on molecular docking studies.

Analysis of ferroelectric properties of ALD-Hf0.5Zr0.5O2 thin films according to oxygen sources

Ferroelectric Hf0.5Zr0.5O2 (HZO) thin films are mostly deposited with a thickness of less than 10 nm by an atomic layer deposition (ALD) process. Since the oxygen source used in the ALD process affects the residues in the deposited HZO films, the choice of oxygen source can be one of the important factors to improve ferroelectricity. From this point of view, the ferroelectric properties of 10-nm-thick ALD-HZO films according to the oxygen source (O3, H2O, and D2O) were comprehensively analyzed in this study. Heavy water (deuterium water, D2O) was used as a tracer to pinpoint the origin of hydrogen that could be derived from unreacted metal precursors or unreacted hydroxyl groups. As a result, it was revealed that the decrease in ferroelectric polarization and increase in leakage current observed in the H2O- and D2O-based HZO capacitors compared to the O3-based HZO capacitor were due to the oxygen source. These results highlight the importance of using O3 as a hydrogen-free oxygen source in the ALD process to achieve better ferroelectricity.

Sequentially PVD‐Grown Indium and Gallium Selenides Under Compositional and Layer Thickness Variation: Preparation, Structural and Optical Characterization

AbstractGroup IIIA metal chalcogenides are an auspicious material system due to their variability of properties and hence the multitude of application options, for example, in the fields of optoelectronic, thermoelectric, piezo‐, and ferroelectric devices. Indium and gallium selenide films are innovatively grown in a sequential PVD (physical vapor deposition) process starting from metal precursor layers of various thicknesses, which are then subject to chalcogenization in different selenium contents. The resulting thin films are investigated for structural and optical properties by Raman, XRD (X‐ray diffraction), and UV–Vis–NIR spectrometry, revealing that all the compounds In2Se3, InSe, In4Se3, Ga2Se3, and GaSe as well as different polytypes can be achieved depending on the metal/chalcogen ratio. Results from Raman and XRD spectroscopy are highly consistent, and also from the optical measurements changes in absorption characteristics can be correlated. The results indicate, that by fine‐tuning the selenium content, deliberately growing ultra‐thin layers of the different indium and gallium phases will be possible, thus opening up a promising route for 2D material fabrication. Given the scalability of the fabrication method, it is highly promising for large‐scale deployment of the materials.