Oxide Research Articles

Binding Kinetics of Self-Assembled Monolayers of Fluorinated Phosphate Ester on Metal Oxides for Underwater Aerophilicity.

The term "aerophilic surface" is used to describe superhydrophobic surfaces in the Cassie-Baxter wetting state that can trap air underwater. To create aerophilic surfaces, it is essential to achieve a synergy between a low surface energy coating and substrate surface roughness. While a variety of techniques have been established to create surface roughness, the development of rapid, scalable, low-cost, waste-free, efficient, and substrate-geometry-independent processes for depositing low surface energy coatings remains a challenge. This study demonstrates that fluorinated phosphate ester, with a surface tension as low as 15.31 mN m-1, can form a self-assembled monolayer on metal oxide substrates within seconds using a facile wet-chemical approach. X-ray photoelectron spectroscopy was used to analyze the formed self-assembled monolayers. Using nanotubular morphology as a rough substrate, we demonstrate the rapid formation of a superhydrophobic surface with a trapped air layer underwater.

Solid-State Nuclear Magnetic Resonance Spectroscopy for Surface Characterization of Metal Oxide Nanoparticles: State of the Art and Perspectives.

Metal oxide materials have found wide applications across diverse fields; in most cases, their functionalities are dictated by their surface structures and properties. A comprehensive understanding of the intricate surface features is critical for their further design, optimization, and applications, necessitating multi-faceted characterizations. Recent advances in solid-state nuclear magnetic resonance (ssNMR) spectroscopy have significantly extended its applications in the detailed analysis of multiple metal oxide nanoparticles, offering unparalleled atomic-level information on the surface structures, properties, and chemistries. Herein, we present an overview of the current state of the art from an NMR perspective. We begin with a brief introduction to contemporary ssNMR methodologies. Subsequently, we introduce and provide critical reviews on the applications of different ssNMR techniques in the detailed characterizations of the surface local structures, disorders, defects, active sites, and acidity on metal oxide nanoparticles, as well as the revelation of mechanisms behind some intriguing chemistries that occur on the surfaces, referencing representative recent studies. Finally, we address the challenges beyond the current status and provide perspectives on the future development and application of advanced ssNMR methodologies in this emerging field.

EFFECTS OF GREEN SYNTHESIZED PHOSPHONOAMIDE AND PHOSPHONOCAPROLACTAM COMPOUNDS IN THE CLAMS RUDITAPES DECUSSATUS

Derivatives of phosphonoamide and phosphonocaprolactam are well-known for their extensive uses in industrial and medical settings. This has raised worries regarding their toxicity to aquatic life as well as their fate in the ecosystem. Thus, for seven days, biomarkers of oxidative stress, neurotoxicity, and metal accumulation were assessed in clams Ruditapes decussatus exposed to 20 and 40 μg/L of N-(2-(diphenylphosphoryl)-2-(thiophen-2-yl) ethyl) acetamide, N-(2-(diphenylphosphoryl)-2-(furan-2-yl) ethyl) acetamide, N-(2-(diphenylphosphoryl)-2-phenylethyl) acetamide, and 7-((diphenylphosphoryl) (phenyl)methyl) azepan-2-one. The results of the metals content analysis indicate that phosphonoamide and phosphonocaprolactam caused metal dyshomeostasis in the digestive gland and gills of clams, with greater levels of zinc and copper detected in the digestive glad following exposure. Phosphonoamide and phosphonocaprolactam derivatives activated biomarkers of oxidative stress, such as GSH, CAT, and MDA, in an organ, concentration, and biomarker dependent manner, exhibiting distinct antioxidant patterns in the digestive glands and gills. By the time the exposure period for both types of phosphorus compounds came to a conclusion, neurotoxic effects were evident in the form of AChE inhibition. Our results demonstrate that filter-feeding species should be taken into consideration when assessing the overall toxicological impact of phosphorus compounds in the aquatic environment. Overall, this exploration was anticipated to yield insights into the distinct responses triggered by these compounds and offer a deeper understanding of the toxicity mechanisms associated with phosphonoamide and phosphonocaprolactam. Additionally, the study highlights the necessity for continuous monitoring of potentially toxic phosphorus compounds in edible marine species to avoid possible repercussions of seafood consumption on human health.

Multielement-Doped Tungstic Acids via Submerged Photosynthesis for Enhanced All-Solar Photoelectrochemical Responses.

Bifunctional electrode materials that can convert solar energy into electricity and store chemical energy are a functional strategy for resolving the instability of solar energy. However, most commonly used transition metal oxide semiconductor materials lack broadband wavelength absorption responses, resulting in incomplete solar energy utilization. Herein, multielement-doped MoxW1-xO3·0.33H2O nanoparticles synthesized via the one-pot submerged photosynthesis of crystallite (SPsC) method are proposed to improve the full-spectrum solar responses of tungstic acids. The solar absorption efficiency of MoxW1-xO3·0.33H2O increases from 54 to 81% after Cu, Fe, and Mn doping. This increase in the solar absorption efficiency of MoxW1-xO3·0.33H2O improves its photogenerated capacitance by 18.7 times, which is attributed to the increase in the number of photogenerated charge carriers and planar defect structures produced via multielement doping. Moreover, ab initio calculations theoretically explain the relation between the elemental doping and corresponding absorption wavelengths of MoxW1-xO3·0.33H2O, providing instructions for tuning the light absorption wavelength of transition metal oxide semiconductor materials. Multielement doping achieved via the low-cost SPsC method enhances the photocarrier response to increase the photogenerated capacitance. This response demonstrates the importance of full-spectrum solar absorption, offering a prominent strategy for designing solar energy storage materials in the future.

Sensors on Flapping Wings (SOFWs) Using Complementary Metal–Oxide–Semiconductor (CMOS) MEMS Technology

This article presents a framework of using MEMS sensors to investigate unsteady flow speeds of a flapping wing or the new concept of sensors on flapping wings (SOFWs). Based on the implemented self-heating flow sensor using U18 complementary metal–oxide–semiconductor (CMOS) MEMS foundry provided by the Taiwan Semiconductor Research Institute (TSRI), the compact sensing region of the flow sensor was incorporated for in situ diagnostics of biomimetic flapping issues. The sensitivity of the CMOS MEMS flow sensor, packaged with a parylene coating of 10 μm thick to prolong the lifetime, was observed as −3.24 mV/V/(m/s), which was below the flow speed of 6 m/s. A comprehensive investigation was conducted on integrating CMOS MEMS flow sensors on the leading edge of the mean aerodynamic chord (m.a.c.) of the flexible 70-cm-span flapping wings. The interpreted flow speed signals were checked and demonstrated similar behavior with the (net) thrust force exerted on the flapping wing, as measured in the wind tunnel experiments using the force gauge. The experimental results confirm that the in situ measurements using the concept of SOFWs can be useful for measuring the aerodynamic forces of flapping wings effectively, and it can also serve for future potential applications.

Electrochemical aptasensor based on zirconium/copper oxides embedded in mesoporous carbon derived from bimetallic metal-organic framework for ultrasensitive detection of miR-21.

A novel electrochemical aptasensor based on bimetallic zirconium and copper oxides embedded within mesoporous carbon (denoted as ZrO2CuOx@mC) was constructed to detect miRNA. The porous ZrO2CuOx@mC was created through the pyrolysis of bimetallic zirconium/copper-based metal-organic framework (ZrCu-MOF). The substantial surface area and high porosity of ZrO2CuOx@mC nanocomposite along with its robust affinity toward aptamer strands, facilitated the effective anchoring of aptamer strands on the ZrO2CuOx@mC-modified electrode surface. This, coupled with the remarkable electrochemical performance arising from the presence of metal oxides and mesoporous carbon, resulted in the exceptional sensitivity of the ZrO2CuOx@mC-based aptasensor for the detection of miR-21. The prepared aptasensor not only demonstrated a broad detection range from 10 zM to 100 pM, featuring an exceptionally low detection limit of 0.52 zM, but also exhibited notable selectivity against interferences. Moreover, it displayed good stability, reproducibility, and acceptable applicability for miR-21 detection in human serum. The fabricated aptasensor offers a promising platform for ultrasensitive miR-21 detection, with potential applications in accurate and early diagnosis of diseases related to miRNA.

Deciphering key nano-bio interface descriptors to predict nanoparticle-induced lung fibrosis

BackgroundThe advancement of nanotechnology underscores the imperative need for establishing in silico predictive models to assess safety, particularly in the context of chronic respiratory afflictions such as lung fibrosis, a pathogenic transformation that is irreversible. While the compilation of predictive descriptors is pivotal for in silico model development, key features specifically tailored for predicting lung fibrosis remain elusive. This study aimed to uncover the essential predictive descriptors governing nanoparticle-induced pulmonary fibrosis.MethodsWe conducted a comprehensive analysis of the trajectory of metal oxide nanoparticles (MeONPs) within pulmonary systems. Two biological media (simulated lung fluid and phagolysosomal simulated fluid) and two cell lines (macrophages and epithelial cells) were meticulously chosen to scrutinize MeONP behaviors. Their interactions with MeONPs, also referred to as nano-bio interactions, can lead to alterations in the properties of the MeONPs as well as specific cellular responses. Physicochemical properties of MeONPs were assessed in biological media. The impact of MeONPs on cell membranes, lysosomes, mitochondria, and cytoplasmic components was evaluated using fluorescent probes, colorimetric enzyme substrates, and ELISA. The fibrogenic potential of MeONPs in mouse lungs was assessed by examining collagen deposition and growth factor release. Random forest classification was employed for analyzing in chemico, in vitro and in vivo data to identify predictive descriptors.ResultsThe nano-bio interactions induced diverse changes in the 4 characteristics of MeONPs and had variable effects on the 14 cellular functions, which were quantitatively evaluated in chemico and in vitro. Among these 18 quantitative features, seven features were found to play key roles in predicting the pro-fibrogenic potential of MeONPs. Notably, IL-1β was identified as the most important feature, contributing 27.8% to the model’s prediction. Mitochondrial activity (specifically NADH levels) in macrophages followed closely with a contribution of 17.6%. The remaining five key features include TGF-β1 release and NADH levels in epithelial cells, dissolution in lysosomal simulated fluids, zeta potential, and the hydrodynamic size of MeONPs.ConclusionsThe pro-fibrogenic potential of MeONPs can be predicted by combination of key features at nano-bio interfaces, simulating their behavior and interactions within the lung environment. Among the 18 quantitative features, a combination of seven in chemico and in vitro descriptors could be leveraged to predict lung fibrosis in animals. Our findings offer crucial insights for developing in silico predictive models for nano-induced pulmonary fibrosis.

The Influence of Carbon Nanotube Composites of Precious Metals and Non-precious Metal Oxides on the Electrode Performance of Supercapacitors

As the problems of energy shortage and environmental pollution are increasingly escalating, the development of efficient and sustainable energy storage technologies has become extremely important. Among these technologies, supercapacitors are receiving significant attention due to their relatively high energy density and power density, making them a promising solution for future energy needs. The unique combination of fast charge-discharge capability, long cycle life, and reliability makes supercapacitors attractive in fields such as portable electronic devices, electric vehicles, and renewable energy integration. In particular, composite materials containing carbon nanotubes and metal oxides are of great research interest in improving the performance of supercapacitors. For example, incorporating non-precious metal oxides (such as manganese oxide and nickel oxide) or precious metal oxides (such as ruthenium oxide) into carbon-based materials can significantly enhance electrochemical performance. An appropriate loading quantity of active materials plays a crucial role in achieving high specific capacitance. Furthermore, different composite preparation techniques have a significant impact on the microstructure of the materials, thereby markedly changing the electrochemical characteristics of the electrode and affecting its overall performance in energy storage systems.

P-type surface charge transfer doping of diamond via low-dimensional transition metal oxides

Device applications of ultra-wide-bandgap diamond rely on the precise control of both carrier type and concentration. However, due to the strong covalent bonds in bulk diamond, conventional doping methods have struggled to achieve large-scale tuning of its properties. Surface charge transfer doping (SCTD) is seen as a simple and effective solution, leveraging energy-level differences between surface dopant and the semiconductor to regulate carrier properties efficiently. Here, we conducted a comprehensive theoretical study on p-type SCTD of hydrogen-terminated diamond (100) surface [diamond(100):H] using low-dimensional transition metal oxides. The doping effects of the molecular MoO3 and monolayer MoO3 were first explored. The areal hole density for molecular-MoO3-doped diamond(100):H sharply rises and then slightly decreases with increasing MoO3 density, reaching a peak of 7.55 × 1013 cm−2—surpassing the maximum value achieved with a MoO3 monolayer. For identical MoO3 densities, a stronger interaction with diamond(100):H results in a greater areal hole density. We also studied one-dimensional chain-like CrO3 and two-dimensional layered V2O5. However, a V2O5 monolayer cannot achieve the saturation areal hole density due to the large energy separation between the conduction band minimum (CBM) of V2O5 and the valence band maximum (VBM) of diamond(100):H. Increasing the number of V2O5 monolayers will enhance the doping effect. Overall, optimal doping can be achieved with smaller dimensions, higher density and thickness of the transition metal oxides, stronger interactions with diamond(100):H, and a larger energy separation between the dopant's CBM and diamond(100):H's VBM. This study provides theoretical guidance to develop superior diamond-based electronic and optoelectronic devices.

Sequential Infiltration Synthesis of Cadmium Sulfide Discrete Atom Clusters.

Exposure of soft material templates to alternating volatile chemical precursors can produce inorganic deposition within the permeable template (e.g. a polymer thin film) in a process akin to atomic layer deposition (ALD). While such sequential infiltration synthesis (SIS) processes have now been demonstrated for many metal oxides, we report an SIS process for a transition metal sulfide - CdS. Gas phase dimethyl cadmium and hydrogen sulfide precursors infiltrated into poly(4-vinylpyridine) thin films result in the 3D-nucleation of clusters consistent with a cubane-type Cd4S4 core that are variably terminated with methyl, thiol and hydroxy capping ligands. First principles models and simulation of few-atom Cd-based clusters are consistent with electronic and vibrational spectroscopy and grazing-incidence total X-ray scattering measurements of 3D-cluster-arrays synthesized at 80 °C. The direct synthesis of few-atom transition metal sulfide clusters within polymer thin films will provide a versatile new route to precision architectures for light-absorbing materials including solar energy harvesting and conversion applications.

Advances of immunosensors based on noble metal composite materials for detecting procalcitonin.

Procalcitonin (PCT) is a reliable biomarker for diagnosing and monitoring bacterial infections and sepsis. PCT exhibits good stability both in vivo and in vitro, and its levels drastically increase in response to bacterial infection or inflammatory reactions in the human body, making it a dependable indicator for sepsis diagnosis and monitoring with significant implications for clinical diagnosis and treatment guidance. Currently, immunosensors are widely utilized in PCT detection due to their high sensitivity and low detection limits. Noble metals, because of their excellent electronic conductivity, biocompatibility, and superior physicochemical properties, are extensively combined with other materials to play a pivotal role in the construction of PCT immunosensors. This review summarizes the research progress on PCT antigen immunosensors based on noble metal composite materials, encompassing the classification and principles of immunosensors. Starting from noble metals, which are widely used as electrode materials in sensors, the review categorizes and discusses the carbon materials, metal oxides, metal sulfides, and other composites with noble metals. The reviewalso elaborates on the influence of sensitive materials on the performance of immunosensors. Finally, the review discusses and anticipates the challenges and future opportunities for the research on PCT antigen immunosensors using noble metal-composite nanomaterials, providing new insights and directions for their application in the treatment and clinical management of sepsis and other diseases.

Sequential Infiltration Synthesis of Cadmium Sulfide Discrete Atom Clusters

AbstractExposure of soft material templates to alternating volatile chemical precursors can produce inorganic deposition within the permeable template (e.g. a polymer thin film) in a process akin to atomic layer deposition (ALD). While such sequential infiltration synthesis (SIS) processes have now been demonstrated for many metal oxides, we report an SIS process for a transition metal sulfide – CdS. Gas phase dimethyl cadmium and hydrogen sulfide precursors infiltrated into poly(4‐vinylpyridine) thin films result in the 3D‐nucleation of clusters consistent with a cubane‐type Cd4S4 core that are variably terminated with methyl, thiol and hydroxy capping ligands. First principles models and simulation of few‐atom Cd‐based clusters are consistent with electronic and vibrational spectroscopy and grazing‐incidence total X‐ray scattering measurements of 3D‐cluster‐arrays synthesized at 80 °C. The direct synthesis of few‐atom transition metal sulfide clusters within polymer thin films will provide a versatile new route to precision architectures for light‐absorbing materials including solar energy harvesting and conversion applications.

Graphene-Based, Flexible, Wearable Piezoresistive Sensors with High Sensitivity for Tiny Pressure Detection

Flexible, wearable, piezoresistive sensors have significant potential for applications in wearable electronics and electronic skin fields due to their simple structure and durability. Highly sensitive, flexible, piezoresistive sensors with the ability to monitor laryngeal articulatory vibration supply a new, more comfortable and versatile way to aid communication for people with speech disorders. Here, we present a piezoresistive sensor with a novel microstructure that combines insulating and conductive properties. The microstructure has insulating polystyrene (PS) microspheres sandwiched between a graphene oxide (GO) film and a metallic nanocopper-graphene oxide (n-Cu/GO) film. The piezoresistive performance of the sensor can be modulated by controlling the size of the PS microspheres and doping degree of the copper nanoparticles. The sensor demonstrates a high sensitivity of 232.5 kPa−1 in a low-pressure range of 0 to 0.2 kPa, with a fast response of 45 ms and a recovery time of 36 ms, while also exhibiting excellent stability. The piezoresistive performance converts subtle laryngeal articulatory vibration into a stable, regular electrical signal; in addition, there is excellent real-time monitoring capability of human joint movements. This work provides a new idea for the development of wearable electronic devices, healthcare, and other fields.

Unraveling 3d Transition Metal (Ni, Co, Mn, Fe, Cr, V) Ions Migration in Layered Oxide Cathodes: A Pathway to Superior Li-Ion and Na-Ion Battery Cathodes.

Li-ion and Na-ion batteries are promising systems for powering electric vehicles and grid storage. Layered 3d transition metal oxides AxTMO2 (A = Li, Na; TM = 3d transition metals; 0<x≤2) have drawn extensive attention as cathode materials due to their exceptional energy densities. However, they suffer from several technical challenges caused by crystal structure degradation associated with TM ions migration, such as poor cycling stability, inferior rate capability, significant voltage hysteresis, and serious voltage decay. Aiming to tackle these challenges, this review provides an in-depth discussion and comprehensive understanding of the TM ions migration behaviors in AxTMO2. First, the key thermodynamics and kinetics that impact TM ions migration are discussed, covering ionic radius, electronic configuration, crystal structure arrangement, and migration energy barrier. In particular, details are provided regarding the universal and specific migration characteristics of Ni, Co, Mn, Fe, Cr, and V ions in layered cathode materials. Subsequently, the impacts of these migrations on electrochemical performance are emphasized in terms of the fundamental science behind technical issues, and strategies to modulate TM ions migration for advanced cathode materials development are summarized. Besides, characterization techniques for probing the TM ions migration are present, like neutron diffraction (ND), scanning transmission electron microscopy (STEM), nuclear magnetic resonance (NMR), and others. Finally, future directions in this regard are comprehensively concluded. This review offers valuable insights into the basic design of advanced layered oxide cathode materials for Li-ion and Na-ion batteries.

Dielectric Constant of a Single MoO3 Nanostructure.

MoO3 is a promising transition metal oxide due to its high dielectric constant (κ) and multifunctionality in electronic and optoelectronic applications. Oxidation-induced nanoscale MoO3, synthesized via oxidation scanning probe lithography (o-SPL) of MoS2, requires in-depth characterization of its dielectric properties. In this study, we measured the κ of a single MoO3 nanostructure, which was confirmed to be in the amorphous phase through water solubility tests and high-resolution transmission electron microscopy (HRTEM). Using electrostatic force microscopy (EFM) and numerical calculations, we determined a high κ value of approximately 25, nearly six times higher than that of SiO2. Additionally, nanoscale κ imaging revealed that the κ of MoO3 nanostructures is independent of their size. These findings suggest that oxidation-induced MoO3 nanostructures are promising candidates as high-κ dielectric materials for future nanoscale devices.

Tailoring the Electrocatalytic Activity and Corrosion Resistance of CoCrFeNi and MnCrFeNi Thin Films by Anodization

AbstractTransition metal oxides like Co, Ni, and Mn are promising alternatives to noble metals such as Pt for oxygen electrocatalysis in green energy. Alloying these metals forms multicomponent catalysts with compelling properties. In this study, CoCrFeNi and MnCrFeNi thin films are synthesized using High‐Power Impulse Magnetron Sputtering (HiPIMS) and their catalytic activity for the Oxygen Reduction Reaction (ORR), the Oxygen Evolution Reaction (OER), and corrosion resistance in 1 molar (1 M) potassium hydroxide (KOH) are evaluated. MnCrFeNi films exhibit a fine‐grained single face‐centered cubic (FCC) phase, while CoCrFeNi films have larger grains and multiple phases. ORR on CoCrFeNi follows a 2+1 electron transfer pathway, producing hydroxide radicals, while MnCrFeNi exhibits a 2‐electron pathway, yielding hydrogen peroxide. Anodization reduces the CoCrFeNi overpotential from 0.9 to 0.5 V versus the reversible hydrogen electrode (RHE), comparable to platinum and iridium catalysts (Pt/C, Ir/C). Anodization also shifts CoCrFeNi ORR to a 2‐electron pathway. In situ Raman spectroscopy detects no ORR intermediates, but nickel oxyhydroxide (NiOOH) appears during OER. Substituting Mn for Co increases corrosion resistance by raising the corrosion potential. All films show passive behavior during polarization, demonstrating their potential for corrosion protection and electrocatalysis in green energy applications.

A Critical Review of the Phenomenon of Inhibiting Asphaltene Precipitation in the Petroleum Industry

This comprehensive review examines chemical and nano-based methods for asphaltene inhibition in the oil industry, focusing on recent developments and challenges. Asphaltene precipitation and deposition remain significant challenges in oil production, affecting wellbore areas, equipment walls, and surface infrastructure. The review analyzes various chemical inhibition mechanisms and evaluation methods, highlighting the emergence of nanotechnology as a promising solution. Metal oxide nanoparticles, organic nanoparticles, and inorganic nonmetal nanoparticles are discussed as effective inhibitors, with particular attention to their performance in different operational conditions, including CO2 flooding processes. The study reveals that nanoparticles’ effectiveness in asphaltene inhibition is attributed to their large specific surface area, strong adsorption capacity, and unique interaction mechanisms with asphaltene molecules. The review also emphasizes the importance of proper inhibitor selection and concentration optimization, as the effectiveness thereof varies with reservoir conditions and crude oil characteristics. Recent developments in functionalized nanoparticles and their applications in enhanced oil recovery are examined, providing insights into future directions for asphaltene management in the petroleum industry.

Interfacial Metal Oxides Stabilize Cu Oxidation States for Electrocatalytical CO2Reduction.

Modulating the oxidation state of copper (Cu) is crucial for enhancing the electrocatalytic CO2 reduction reaction (CO2RR), particularly for facilitating deep reductions to produce methane (CH4) or multi-carbon (C2+) products. However, Cuδ+ sites are thermodynamically unstable, fluctuating their oxidation states under reaction conditions, which complicates their functionality. Incorporating interfacial metal oxides has emerged as an effective strategy for stabilizing these oxidation states. This review provides an in-depth examination of the reaction mechanisms occurring at oxide-modified Cuδ+ sites, offering a comprehensive understanding of their behavior. We explore how Cu/metal oxide interfaces stabilize Cu oxidation states, showing that oxides-modified Cu catalysts often enhance selectivity for C2+ or CH4 products by stabilizing Cu+ or Cu2+ sites. In addition, we discuss innovative strategies for the rational design of efficient Cu catalytic sites tailored for specific deep CO2RR products. The review concludes with an outlook on current challenges and future directions, offering new insights into the rational design of selective and efficient CO2RR catalysts.

Boosting Amino Acid Synthesis with WOx Sub-Nanoclusters.

The conversion of nitrate-rich wastewater and biomass-derived blocks into high-value products using renewably generated electricity is a promising approach to modulate the artificial carbon and nitrogen cycle. Here, a new synthetic strategy of WOx sub-nanoclusters is reported and supported on carbon materials as novel efficient electrocatalysts for nitrate reduction and its coupling with α-keto acids. In acidic solutions, the NH3-NH2OH selectivity can also optimized by adjusting the potential, with the total FE exceeding 80% over a wide potential range. After introducing α-keto acids, the WOx/D-CB electrode achieves remarkable activity and selectivity toward C2-C6 amino acids. For glycine and alanine, impressive FEs of 49.34% and 38.22% based on transitional metal oxides can be obtained, surpassing those of WOx nanoclusters with larger size. In situ analysis and mechanistic studies reveal the critical role of WOx sub-nanoclusters in reducing the energy barriers of key steps in alanine synthesis. This work opens up new insights into the rational design of cluster catalysts to promote electrochemical amino acid synthesis.

Green Synthesis of Metal Oxide Nanoparticles Using Plumbago zeylanica Root Extract, Spectrochemical Characterization, and Antibacterial Activity Against Common Pathogen

ABSTRACTThe root extract of Plumbago zeylanica was used to produce iron oxide (FeO), zinc oxide (ZnO), and copper oxide (CuO) nanoparticles. These metal oxides are easy to produce, inexpensive, and ecologically friendly, with considerable antibacterial activity against common infections. The purpose of this work is to explore a sustainable synthesis method and to investigate the comparative antibacterial activity of these nanoparticles. The nanoparticles were characterized using a variety of techniques, including energy‐dispersive X‐ray (EDX), transmission electron microscopy (TEM), ultraviolet‐visible (UV‐vis) spectrophotometry, X‐ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy. The XRD patterns revealed the crystalline structures of the produced metal oxide nanoparticles by displaying prominent, intense peaks. Morphological investigation utilizing SEM and TEM techniques revealed the nanoparticles’ shapes and sizes, with an average particle size ranging from 9 to 36 nm. EDX spectra verified the presence of an oxide layer on all three metal oxide nanoparticles. UV‐vis and FTIR spectroscopy revealed additional optical characteristics. The antibacterial activities of FeO, ZnO, and CuO nanoparticles were tested using disk diffusion assays against Salmonella enterica, Staphylococcus aureus, and Escherichia coli. The results showed that the antibacterial efficiency of these nanoparticles varied according to the type of bacteria. ZnO nanoparticles had the highest antibacterial activity against both Gram‐positive and Gram‐negative bacteria, while FeO nanoparticles had the lowest antibacterial efficacy. These data imply that ZnO nanoparticles, in particular, have antibacterial properties.