Noble Metal-Based Multimetallic Nanoparticles for Electrocatalytic Applications

A sensitive electrochemical biosensor based on Pd@PdPtCo mesoporous nanopolyhedras as signal amplifiers for assay of cardiac troponin I

Cardiac troponin I (cTnI) has been widely used in clinical diagnosis of acute myocardial infarction (AMI). Herein, a sensitive electrochemical biosensor for cTnI analysis was designed, in which the simple synthesized Pd@PdPtCo mesoporous nanopolyhedras (MNPs) were utilized as signal amplifiers. The mesoporous polyhedral structure of Pd@PdPtCo MNPs endows them with more specific surface area and more active sites, as well as the synergistic effect between multiple metal elements, all of which increase the electrocatalytic performance of Pd@PdPtCo MNPs in efficiently oxidizing hydroquinone (HQ) to benzoquinone (BQ). Experimental results showed that Pd@PdPtCo MNPs had better performance in oxidation of HQ to BQ compared with their corresponding monometallic and bimetallic nanomaterials. With the aid of the interaction between antigens and antibodies, the peak current of HQ to BQ showed an upward trend with increasing concentration of cTnI, thus the quantitative detection of cTnI could be achieved. Under optimal conditions, the biosensor prepared in this work has a wider linear range (1.0 × 10-4-200 ng mL-1) and a lower detection limit (0.031 pg mL-1) than other sensors reported in literatures, coupled by good stability and high sensitivity. More importantly, it also performed well in complex serum environment, proving that the electrochemical sensor has a practical application potential in this field.

Symmetry breaking enhances the catalytic and electrocatalytic performance of core/shell tetrametallic porous nanoparticles

The performance of functional nanocatalysts can be extended by integrating multiple types of metals into well-designed nanoparticles. A porous multimetallic shell grown around high-quality monometallic seeds significantly enhances the availability of active sites. Here, tetrametallic core/shell nanoparticles (Au@mPdPtIr) featuring micro- and mesoporous shells are synthesized with strict control over the overall particle morphology. To reveal the impact of the core nanoparticle morphology on the optical, structural and electrocatalytic properties, tetrametallic particles are prepared using gold cores with different shapes but identical volumes and surface chemistry. Our general synthetic approach ensures the successful and reliable synthesis of porous trimetallic shells around the cores, keeping the final atomic composition of the different multimetallic particles identical. The results clearly highlight the significance of the core morphology in the catalytic performance and the superior activity of symmetry-broken core/shell particles in heterogeneous as well as electrocatalytic oxidation reactions. These can be attributed to the fine structural details of the deposited trimetallic shells and their influence on the charge carrier transport between the multimetallic particles and the organic test molecules. While all nanocatalysts show excellent morphological robustness, the optimal morphology also depends on the reaction type and conditions of the specific reaction.

N-Heterocyclic carbene-stabilized gold-copper nanoclusters: synthesis, bonding and mechanochromism

N-Heterocyclic carbene (NHC) ligands have emerged as highly effective surface ligands for the protection and functionalization of metal nanoclusters (NCs). However, research on NHC-stabilized metal NCs, including their synthesis, structure, properties, and applications, is still in its early stages. In this study, we present the first gold-copper alloy cluster protected by both NHC and alkyne ligands, denoted as Au3Cu(iPrNHCiPr)(PA)4 (abbreviated as Au3Cu, where iPrNHCiPr is a bidentate N-heterocyclic carbene ligand with isopropyl as the N-substituent, and PA is a phenylethynyl group). The precise composition of Au3Cu was confirmed through the utilization of electrospray ionization mass spectrometry (ESI-MS), and its structure was determined via X-ray single-crystal diffraction. It is worth noting that although the Au3Cu clusters do not display substantial light emission when exposed to UV lamps, they are capable of emitting green fluorescence subsequent to undergoing mechanical milling (λem = 500 nm). Powder X-ray diffraction (PXRD) analysis reveals that this transition is attributed to a crystalline-amorphous transformation of the cluster crystals. These atomically precise alloy clusters are expected to serve as a model for further investigation into the principles of mechanical milling of metal clusters for discolouration.

Freestanding Penta-Twinned Pd-Ag Nanosheets

2D metal nanosheets have attracted significant attention as efficient catalysts for various important chemical reactions. However, the development of metal nanosheets with controlled compositions and morphologies has been slow due to the challenges associated with synthesizing thermodynamically unfavorable 2D structures. Herein, we report a synthesis route of freestanding Pd-Ag penta-twinned nanosheets (Pd-Ag ptNSs) with distinct 5-fold twin boundaries. Through the coreduction of Ag and Pd precursors on presynthesized Pd ptNSs, Ag could be homogeneously alloyed with Pd, leading to the formation of well-defined Pd-Ag ptNSs. The promotional effects of the bimetallic composition, 2D structure, and twin boundaries on catalysis were studied by using Pd-Ag ptNS-catalyzed H2 production from formic acid decomposition as a model reaction. Notably, the catalytic activity of the Pd-Ag ptNSs drastically outperformed those of monometallic, bimetallic, and 3D counterparts, such as Pd ptNSs, Pd-Ag nanosheets without a TB, and Pd-Ag octahedral nanocrystals, demonstrating the promising potential of the integration of twin boundaries and multiple compositions in the development of high-performance 2D nanocatalysts.

Cuboctahedral Pd13 as a spherical aromatic noble metal core: insights from a ligand-protected [Pd13(Tr)6]2+ cluster

Low-valent palladium nanoparticles are efficient species promoting catalytic activity and selectivity in a number of chemical reactions. Recently, an atom-centered cuboctahedral Pd13 motif has been characterized as a ligand-protected [Pd13(Tr)6]2+ cluster featuring a 1s2 superatomic shell structure. In this report, we describe the ligand-cluster of and endohedral-cage interaction in [Pd13(Tr)6]2+, which accounts for a favorable situation in the overall cluster. In addition, the spherical aromatic properties of the cluster were evaluated to understand the behavior of the ligand-protected Pd13 cluster core. Our results indicate a sizable interaction towards carbon-based ligands in an overall spherical aromatic cluster featuring a long-range shielding cone. Thus, [Pd13(Tr)6]2+ is rationalized as the first ligand-protected palladium cluster to date exhibiting spherical aromatic properties, serving as a stable building block for molecule-based materials or as a dopant in porous carbon materials.

Anchoring Frustrated Lewis Pair Active Sites on Copper Nanoclusters for Regioselective Hydrogenation

In recent years, the concept of Frustrated Lewis Pairs (FLPs), which consist of a combination of Lewis acid (LA) and Lewis base (LB) active sites arranged in a suitable geometric configuration, has been widely utilized in homogeneous catalytic reactions. This concept has also been extended to solid supports such as zeolites, metal oxide surfaces, and metal/covalent organic frameworks, resulting in a diverse range of heterogeneous FLP catalysts that have demonstrated notable efficiency and recyclability in activating small molecules. This study presents the successful immobilization of FLP active sites onto the surface of ligand-stabilized copper nanoclusters with atomic precision, leading to the development of copper nanocluster FLP catalysts characterized by high reactivity, stability, and selectivity. Specifically, thiol ligands containing 2-methoxyl groups were strategically designed to stabilize the surface of [Cu34S7(RS)18(PPh3)4]2+ (where RSH = 2-methoxybenzenethiol), facilitating the formation of FLPs between the surface copper atoms (LA) and ligand oxygen atoms (LB). Experimental and theoretical investigations have demonstrated that these FLPs on the cluster surface can efficiently activate H2 through a heterolytic pathway, resulting in superior catalytic performance in the hydrogenation of alkenes under mild conditions. Notably, the intricate yet precise surface coordination structures of the cluster, reminiscent of enzyme catalysts, enable the hydrogenation process to proceed with nearly 100% selectivity. This research offers valuable insights into the design of FLP catalysts with enhanced activity and selectivity by leveraging surface/interface coordination chemistry of ligand-stabilized atomically precise metal nanoclusters.

Modification Strategies for Development of 2D Material-Based Electrocatalysts for Alcohol Oxidation Reaction

2D materials, such as graphene, MXenes (metal carbides and nitrides), graphdiyne (GDY), layered double hydroxides, and black phosphorus, are widely used as electrocatalyst supports for alcohol oxidation reactions (AORs) owing to their large surface area and unique 2D charge transport channels. Furthermore, the development of highly efficient electrocatalysts for AORs via tuning the structure of 2D support materials has recently become a hot area. This article provides a critical review on modification strategies to develop 2D material-based electrocatalysts for AOR. First, the principles and influencing factors of electrocatalytic oxidation of alcohols (such as methanol and ethanol) are introduced. Second, surface molecular functionalization, heteroatom doping, and composite hybridization are deeply discussed as the modification strategies to improve 2D material catalyst supports for AORs. Finally, the challenges and perspectives of 2D material-based electrocatalysts for AORs are outlined. This review will promote further efforts in the development of electrocatalysts for AORs.

Single Entity Electrocatalysis

Making a measurement over millions of nanoparticles or exposed crystal facets seldom reports on reactivity of a single nanoparticle or facet, which may depart drastically from ensemble measurements. Within the past 30 years, science has moved toward studying the reactivity of single atoms, molecules, and nanoparticles, one at a time. This shift has been fueled by the realization that everything changes at the nanoscale, especially important industrially relevant properties like those important to electrocatalysis. Studying single nanoscale entities, however, is not trivial and has required the development of new measurement tools. This review explores a tale of the clever use of old and new measurement tools to study electrocatalysis at the single entity level. We explore in detail the complex interrelationship between measurement method, electrocatalytic material, and reaction of interest (e.g., carbon dioxide reduction, oxygen reduction, hydrazine oxidation, etc.). We end with our perspective on the future of single entity electrocatalysis with a key focus on what types of measurements present the greatest opportunity for fundamental discovery.

In-Flight Tuning of Au-Sn Nanoparticle Properties

Multimetallic nanoparticles possess a variety of beneficial properties with potential relevance for various applications. These metallic nanoparticles can consist of randomly ordered alloys, which retain the properties of the constituting elements, or ordered intermetallics, which possess extended properties. Depending on the desired application, specific alloys or intermetallic compounds are required. However, it remains challenging to achieve particular morphologies, crystal structures, chemical compositions, and particle sizes because of the inherent complexity of nanoparticle synthesis. In this work, Au-Sn nanoparticles were synthesized using a continuous one-step gas-phase synthesis method that offers the possibility to anneal the nanoparticles in flight directly after generation to tune their properties. The bimetallic model system Au-Sn, comprising both alloys and intermetallic compounds, was studied in the temperature range of 300 to 1100 °C. The bimetallic Au/Sn ratio in the nanoparticles can be adjusted with in-flight annealing between 70/30 and 40/60 atomic %. While Au-rich alloys are obtained at lower temperatures, the increase in the annealing temperature leads to the formation of more Sn-rich intermetallic phases. Surface and size effects greatly influence particle morphologies and phase fractions. This research opens new opportunities for the synthesis of customized nanoparticles by temperature adjustment and particle size selection.

H-Glass Supported Hybrid Gold Nano-Islands for Visible-Light-Driven Hydrogen Evolution

Flat panel reactors, coated with photocatalytic materials, offer a sustainable approach for the commercial production of hydrogen (H2) with zero carbon footprint. Despite this, achieving high solar-to-hydrogen (STH) conversion efficiency with these reactors is still a significant challenge due to the low utilization efficiency of solar light and rapid charge recombination. Herein, hybrid gold nano-islands (HGNIs) are developed on transparent glass support to improve the STH efficiency. Plasmonic HGNIs are grown on an in-house developed active glass sheet composed of sodium aluminum phosphosilicate oxide glass (H-glass) using the thermal dewetting method at 550 °C under an ambient atmosphere. HGNIs with various oxidation states (Au0, Au+, and Au-) and multiple interfaces are obtained due to the diffusion of the elements from the glass structure, which also facilitates the lifetime of the hot electron to be ≈2.94 ps. H-glass-supported HGNIs demonstrate significant STH conversion efficiency of 0.6%, without any sacrificial agents, via water dissociation. This study unveils the specific role of H-glass-supported HGNIs in facilitating light-driven chemical conversions, offering new avenues for the development of high-performance photocatalysts in various chemical conversion reactions for large-scale commercial applications.

Formation of Disordered High-Entropy-Alloy Nanoparticles for Highly Efficient Hydrogen Electrocatalysis

Nanoparticles composed of high-entropy alloys (HEA NPs) exhibit remarkable performance in electrocatalytic processes such as hydrogen evolution and oxidations. In this study, two types of quinary HEA NPs of PtRhPdIrRu, are synthesized, featuring disordered and crystallized nanostructures, both with and without a boiling mixture. The disordered HEA NPs (d-HEA NPs) with a size of 3.5 nm is synthesized under intense boiling conditions, attributed to improved heat and mass transfer during reduction of precursors and particle growth. The disordered HEA NPs displayed an exceptionally high turnover frequency of 33.1 s-1 at an overpotential of 50 mV, surpassing commercial Pt NPs in acidic electrolytes by 5.4 times. Additionally, d-HEA NPs exhibited superior stability at a constant electrolyzing current of 50 mA cm-2 compared to commercial Pt NPs. When employed as the anodic catalyst in an H2-O2 fuel cell, d-HEA NPs demonstrated a remarkable high current power density of 15.3 kW per gram of noble metal. Consequently, these findings highlight the potential of d-HEA NPs in electrochemical applications involving hydrogen.

Eight-Electron Copper Nanoclusters for Photothermal Conversion

Owing to distinct physicochemical properties in comparison to gold and silver counterparts, atomically precise copper nanoclusters are attracting embryonic interest in material science. The introduction of copper cluster nanomaterials in more interesting fields is currently urgent and desired. Reported in this work are novel copper nanoclusters of [XCu54Cl12(tBuS)20(NO3)12] (X=S or none, tBuSH=2-methyl-2-propanethiol), which exhibit high performance in photothermal conversion. The clusters have been prepared in one pot and characterized by combinatorial techniques including ultraviolet-visible spectroscopy (UV-vis), electrospray ionization mass spectrometry (ESI-MS), and X-ray photoelectron spectroscopy (XPS). The molecular structure of the clusters, as revealed by single crystal X-ray diffraction analysis (SCXRD), shows the concentric three-shell Russian doll arrangement of X@Cu14@Cl12@Cu40. Interestingly, the [SCu54Cl12(tBuS)20(NO3)12] cluster contains 8 free valence electrons in its structure, making it the first eight-electron copper nanocluster stabilized by thiolates. More impressively, the clusters possess an effective photothermal conversion (temperature increases by 71 °C within ~50 s, λex=445 nm, 0.5 W cm-2) in a wide wavelength range (either blue or near-infrared). The photothermal conversion can be even driven under irradiation of simulated sunlight (3 sun), endowing the clusters with great potency in solar energy utilization.

Multi-Scale Engineered 2D Carbon Polyhedron Array with Enhanced Electrocatalytic Performance

Electrocatalyst engineering from the atomic to macroscopic level of electrocatalysts is one of the most powerful routes to boost the performance of electrochemical devices. However, multi-scale structure engineering mainly focuses on the range of atomic-to-particle scale such as hierarchical porosity engineering, while catalyst engineering at the macroscopic level, such as the arrangement configuration of nanoparticles, is often overlooked. Here, a 2D carbon polyhedron array with a multi-scale engineered structure via facile chemical etching, ice-templating induced self-assembly, and high-temperature pyrolysis processes is reported. Controlled phytic acid etching of the carbon precursor introduces homogeneous atomic phosphorous and nitrogen doping, as well as a well-defined mesoporous structure. Subsequent ice-templated self-assembly triggers the formation of a 2D particle array superstructure. The atomic-level doping gives rise to high intrinsic activity, while the well-engineered porous structure and particle arrangement addresses the mass transport limitations at the microscopic particle level and macroscopic electrode level. As a result, the as-prepared electrocatalyst delivers outstanding performance toward oxygen reduction reaction in both acidic and alkaline media, which is better than recently reported state-of-the-art metal-free electrocatalysts. Molecular dynamics simulation together with extensive characterizations indicate that the performance enhancement originates from multi-scale structural synergy.

Rapid Synthesis of Noble Metal Colloids by Plasma-Liquid Interactions

The interactions between plasma and liquids cause complex physical and chemical reactions at the gas-liquid contact surface, producing numerous chemically active particles that can rapidly reduce noble metal ions. This study uses atmospheric-pressure surface dielectric barrier discharge (DBD) plasma to treat ethanol aqueous solutions containing noble metal precursors, and stable gold, platinum, and palladium colloids are obtained within a few minutes. To evaluate the mechanism of the reduction of noble metal precursors by atmospheric-pressure surface DBD plasma, the corresponding metal colloids are prepared first by activating an ethanol aqueous solution with plasma and then adding noble metal precursors. It is found that the long-lived active species hydrogen peroxide (H2O2) plays a dominant role in the synthesis process, which has distinct effects on different metal ions. When HAuCl4 and H2PdCl4 are used as precursors, H2O2 acts as a reducing agent, and AuCl4- and PdCl42- ions can be reduced to metallic Au and Pd. However, when AgNO3 is the precursor, H2O2 acts as an oxidising agent, and Ag+ ions cannot be reduced to obtain metal colloids because metallic Ag can be dissolved in H2O2 under acidic conditions. A similar phenomenon was also observed for the preparation of Pd colloid-PA with a plasma-activated ethanol aqueous solution using Pd(NO3)2 as a Pd precursor.

Anti-galvanic reaction induced interfacial engineering to reconstruct ternary colloid satellite platform for exceptionally high-performance redox-responsive sensor

The anti-galvanic reaction (AGR), which is a classic galvanic reaction (GR) with an opposite effect, is a unique phenomenon associated with the quantum size effect. This reaction involves the interaction between metal ions and nanoclusters, offering opportunities to create well-defined nanomaterials and diverse reductive behavior. In hence, in our work, we utilize the AGR to generate gold (Au), silver (Ag), and copper (Cu) satellite nanoclusters which have superior electromagnetic properties for Surface-enhanced Raman spectroscopy (SERS) sensor. As the AGR process, weak oxidant Cu2+ is selected to etched matrix Au@Ag NPs, reduced to Cu(0) or Cu(1) and generated the ultrasmall metal nanoparticles (Ag). To facilitate the AGR, we introduce the nucleophilic thiol 4-mercaptopyridine (4-Mpy) to bridge the metal ions or ultrasmall metal nanoparticles to reconstruct the satellite nanoclusters. These experimental displays that the AGR based biosensors has highly sensitivity for reductive molecule glucose. The liner ranges from 1 mmol/L to 1 nmol/L and alongs with a correlation coefficient and detection limit (LOD) of 0.999 and 0.14 nmol/L. Moreover, the AGR based biosensors exhibits remarkable stability and high repeatability with RSD 1.3 %. The food samples are tested to further investigate the accuracy and reliability of the method, which provides a novel and effective SERS method for the reduction molecules detection.

Electrochemical Sensors Based on Transition Metal Materials for Phenolic Compound Detection

Electrochemical sensors have been recognized as crucial tools for monitoring comprehensive chemical information, especially in the detection of a significant class of molecules known as phenolic compounds. These compounds can be present in water as hazardous analytes and trace contaminants, as well as in living organisms where they regulate their metabolism. The sensitive detection of phenolic compounds requires highly efficient and cost-effective electrocatalysts to enable the development of high-performance sensors. Therefore, this review focuses on the development of advanced materials with excellent catalytic activity as alternative electrocatalysts to conventional ones, with a specific emphasis on transition metal-based electrocatalysts for the detection of phenolic compounds. This research is particularly relevant in diverse sectors such as water quality, food safety, and healthcare.

Electrocatalytic CO2 Reduction to Ethylene: From Advanced Catalyst Design to Industrial Applications

The value-added chemicals, monoxide, methane, ethylene, ethanol, ethane, and so on, can be efficiently generated through the electrochemical CO2 reduction reaction (eCO2 RR) when equipped with suitable catalysts. Among them, ethylene is particularly important as a chemical feedstock for petrochemical manufacture. However, despite its high Faradaic efficiency achievable at relatively low current densities, the substantial enhancement of ethylene selectivity and stability at industrial current densities poses a formidable challenge. To facilitate the industrial implementation of eCO2 RR for ethylene production, it is imperative to identify key strategies and potential solutions through comprehending the recent advancements, remaining challenges, and future directions. Herein, the latest and innovative catalyst design strategies of eCO2 RR to ethylene are summarized and discussed, starting with the properties of catalysts such as morphology, crystalline, oxidation state, defect, composition, and surface engineering. The review subsequently outlines the related important state-of-the-art technologies that are essential in driving forward eCO2 RR to ethylene into practical applications, such as CO2 capture, product separation, and downstream reactions. Finally, a greenhouse model that integrates CO2 capture, conversion, storage, and utilization is proposed to present an ideal perspective direction of eCO2 RR to ethylene.

From Multi- to Single-Hollow Trimetallic Nanocrystals by Ultrafast Heating

Metal nanocrystals (NCs) display unique physicochemical features that are highly dependent on nanoparticle dimensions, anisotropy, structure, and composition. The development of synthesis methodologies that allow us to tune such parameters finely emerges as crucial for the application of metal NCs in catalysis, optical materials, or biomedicine. Here, we describe a synthetic methodology to fabricate hollow multimetallic heterostructures using a combination of seed-mediated growth routes and femtosecond-pulsed laser irradiation. The envisaged methodology relies on the coreduction of Ag and Pd ions on gold nanorods (Au NRs) to form Au@PdAg core-shell nanostructures containing small cavities at the Au-PdAg interface. The excitation of Au@PdAg NRs with low fluence femtosecond pulses was employed to induce the coalescence and growth of large cavities, forming multihollow anisotropic Au@PdAg nanostructures. Moreover, single-hollow alloy AuPdAg could be achieved in high yield by increasing the irradiation energy. Advanced electron microscopy techniques, energy-dispersive X-ray spectroscopy (EDX) tomography, X-ray absorption near-edge structure (XANES) spectroscopy, and finite differences in the time domain (FDTD) simulations allowed us to characterize the morphology, structure, and elemental distribution of the irradiated NCs in detail. The ability of the reported synthesis route to fabricate multimetallic NCs with unprecedented hollow nanostructures offers attractive prospects for the fabrication of tailored high-entropy alloy nanoparticles.

Intermetallic Nanocrystals for Fuel-Cells-Based Electrocatalysis

Electrocatalysis underpins the renewable electrochemical conversions for sustainability, which further replies on metallic nanocrystals as vital electrocatalysts. Intermetallic nanocrystals have been known to show distinct properties compared to their disordered counterparts, and been long explored for functional improvements. Tremendous progresses have been made in the past few years, with notable trend of more precise engineering down to an atomic level and the investigation transferring into more practical membrane electrode assembly (MEA), which motivates this timely review. After addressing the basic thermodynamic and kinetic fundamentals, we discuss classic and latest synthetic strategies that enable not only the formation of intermetallic phase but also the rational control of other catalysis-determinant structural parameters, such as size and morphology. We also demonstrate the emerging intermetallic nanomaterials for potentially further advancement in energy electrocatalysis. Then, we discuss the state-of-the-art characterizations and representative intermetallic electrocatalysts with emphasis on oxygen reduction reaction evaluated in a MEA setup. We summarize this review by laying out existing challenges and offering perspective on future research directions toward practicing intermetallic electrocatalysts for energy conversions.

Electron-Redistributed NiCo@NiFe-LDH Core-Shell Heterostructure for Significantly Enhancing Electrochemical Water Splitting

Layered double hydroxides (LDHs) are some of the most promising precursors for the development of economically stable and efficient electrocatalysts for water splitting. An effective strategy for designing excellent performance electrocatalysts is to assemble core-shell heterostructures with a tunable electronic structure. In this work, three core-shell heterostructure electrocatalysts (NiCo@NiFe-LDH100/150/200) are developed by a simple hydrothermal and subsequent electrodeposition method on Ni foam. Among them, NiCo@NiFe-LDH150/NF exhibits the best oxygen evolution reaction electrocatalytic activity and long-term stability with a low overpotential of 197 mV to deliver a current density of 10 mA cm-2. In addition, an efficient and stable alkaline electrolytic cell with NiCo@NiFe-LDH150/NF both as the cathode and anode achieves a voltage of 1.66 V at a current density of 10 mA cm-2 and realization of ultralong stability at current densities of 20 and 200 mA cm-2 for 200 h. Density functional theory calculations reveal the strong electron interaction at the heterogeneous interface of the NiCo@NiFe-LDH150/NF core-shell structure, which effectively improves the intrinsic electron conductivity and ion diffusion kinetics and makes an important contribution to the electrocatalytic performance of the material. This work provides a new idea for the selection of materials for electrochemical water splitting by the construction of heterojunction interfaces.

Parazoanthus axinellae Extract Incorporated Hybrid Nanostructure and Its Potential Antimicrobial Activity

This study, it was aimed to examine the change in the antimicrobial effect of sea anemone Parazoanthus axinellae extract by forming its nanoflowers. A scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX) were expended to observe the morphologies of the Cu NFs that had been produced. Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) techniques were expended to analyze the managing assemblies in P. axinellae extract, which perform an effective part in the synthesis routine, as well as the crystal assembly of NFs. P. axinellae extract mediated the HNFs (Hybrid nanoflowers) are at high, pure crystalline nature, flower shape with a crystallographic system at the nanoscale with mean crystallite size 21.9 nm using XRD, and average particle size ~10 nm by SEM. The broad absorption band at 2981-2915 cm-1 in the FT-IR spectra of anemone extract and Cu-anemone NFs represents the unique peak of hydroxy groups. In addition, Cu NFs were tested for their antibacterial properties. Cu NFs have been discovered to exhibit antibacterial properties. It is suggested that P. axinellae extract and various inorganic components be used to synthesize a variety of NFs and assess their suitability for usage in biomedical fields.

Temporal Evolution of Morphology, Composition, and Structure in the Formation of Colloidal High-Entropy Intermetallic Nanoparticles

Morphology-controlled nanoparticles of high entropy intermetallic compounds are quickly becoming high-value targets for catalysis. Their ordered structures with multiple distinct crystallographic sites, coupled with the "cocktail effect" that emerges from randomly mixing a large number of elements, yield catalytic active sites capable of achieving advanced catalytic functions. Despite this growing interest, little is known about the pathways by which high entropy intermetallic nanoparticles form and grow in solution. As a result, controlling their morphology remains challenging. Here, we use the high entropy intermetallic compound (Pd,Rh,Ir,Pt)Sn, which adopts a NiAs-related crystal structure, as a model system for understanding how nanoparticle morphology, composition, and structure evolve during synthesis in solution using a slow-injection reaction. By performing a time-point study, we establish the initial formation of palladium-rich cube-like Pd-Sn seeds onto which the other metals deposit over time, concomitant with continued incorporation of tin. For (Pd,Rh,Ir,Pt)Sn, growth occurs on the corners, resulting in a sample having a mixture of flower-like and cube-like morphologies. We then synthesize and characterize a library of 14 distinct intermetallic nanoparticle systems that comprise all possible binary, ternary, and quaternary constituents of (Pd,Rh,Ir,Pt)Sn. From these studies, we correlated compositions, morphologies, and growth pathways with the constituent elements and their competitive reactivities, ultimately mapping out a framework that rationalizes the key features of the high entropy (Pd,Rh,Ir,Pt)Sn intermetallic nanoparticles based on those of their simpler constituents. We then validated these design guidelines by applying them to the synthesis of a morphologically pure variant of flowerlike (Pd,Rh,Ir,Pt)Sn particles as well as a series of (Pd,Rh,Ir,Pt)Sn particles with tunable morphologies based on control of composition.

Cobalt Phthalocyanine-Doped Polymer-Based Electrocatalyst for Rechargeable Zinc-Air Batteries

Rechargeable zinc-air batteries (RZAB) have gained significant attention as potential energy storage devices due to their high energy density, cost-effectiveness, and to the fact that they are environmentally safe. However, the practical implementation of RZABs has been impeded by challenges such as sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), including poor cyclability. Herein, we report the preparation of cobalt- and nitrogen-doped porous carbon derived from phloroglucinol-formaldehyde polymer networks with 2-methyl imidazole and cobalt phthalocyanine as precursors for nitrogen and cobalt. The CoN-PC-2 catalyst prepared in this study exhibits commendable electrocatalytic activity for both ORR and OER, evidenced by a half-wave potential of 0.81 V and E_j=10 of 1.70 V. Moreover, the catalyst demonstrates outstanding performance in zinc-air batteries, achieving a peak power density of 158 mW cm^-2 and displaying excellent stability during charge-discharge cycles. The findings from this study aim to provide valuable insights and guidelines for further research and the development of hierarchical micro-mesoporous carbon materials from polymer networks, facilitating their potential commercialisation and widespread deployment in energy storage applications.

Recent Advances in Electrochemical Sensors for Sulfur-Containing Antioxidants

Sulfur-containing antioxidants are an important part of the antioxidant defense systems in living organisms under the frame of a thiol-disulfide equilibrium. Among them, l-cysteine, l-homocysteine, l-methionine, glutathione, and α-lipoic acid are the most typical representatives. Their actions in living systems are briefly discussed. Being electroactive, sulfur-containing antioxidants are interesting analytes to be determined using various types of electrochemical sensors. Attention is paid to the chemically modified electrodes with various nanostructured coverages. The analytical capabilities of electrochemical sensors for sulfur-containing antioxidant quantification are summarized and discussed. The data are summarized and presented on the basis of the electrode surface modifier applied, i.e., carbon nanomaterials, metal and metal oxide nanoparticles (NPs) and nanostructures, organic mediators, polymeric coverage, and mixed modifiers. The combination of various types of nanomaterials provides a wider linear dynamic range, lower limits of detection, and higher selectivity in comparison to bare electrodes and sensors based on the one type of surface modifier. The perspective of the combination of chromatography with electrochemical detection providing the possibility for simultaneous determination of sulfur-containing antioxidants in a complex matrix has also been discussed.

"Two-in-one" core-shell nanozyme probes with double signal amplification for high-performing surface plasmon resonance immunosensing

Herein, a "two-in-one" Ag@Au core-shell nanozyme probe inducing double-signal amplification has been developed to significantly elevate the sensitivity of SPR sensors via sandwich immunoassay. The Ag@Au core-shell nanozyme with intrinsic peroxide-like activity was demonstrated to catalyze a polymerization reaction leading to formation of polyaniline, allowing further improvement of detection performance of SPR immunosensor. The method demonstrated here offers a universal strategy for enhanced SPR detection and further expands the application of nanozymes.

Demystifying the Chemical Ordering of Multimetallic Nanoparticles

ConspectusMultimetallic nanoparticles (NPs) have highly tunable properties due to the synergy between the different metals and the wide variety of NP structural parameters such as size, shape, composition, and chemical ordering. The major problem with studying multimetallic NPs is that as the number of different metals increases, the number of possible chemical orderings (placements of different metals) for a NP of fixed size explodes. Thus, it becomes infeasible to explore NP energetic differences with highly accurate computational methods, such as density functional theory (DFT), which has a high computational cost and is typically applied to up to a couple of hundred metal atoms. Here, we demonstrate a methodology advancing NP simulations by effectively exploring the vast materials space of multimetallic NPs and accurately identifying the ones with the most thermodynamically preferred chemical orderings. With accuracies reaching that of DFT, our methodology is applicable to practically any NP size, shape, and metal composition. We achieve this by significantly advancing the bond-centric (BC) model, a physics-based model that has been previously shown to rapidly predict bimetallic NP cohesive energies (CEs). Specifically, the BC model is trained in a way to understand how the bimetallic bond strength changes under different coordination environments present on a NP and how the metal composition of every site affects the detailed coordination environment using fractional coordination numbers. This newly modified BC model leads to an improvement from 0.331 (original model) to 0.089 eV/atom in CE predictions when compared to DFT values on a robust data set of 90 different NPs consisting of PtPd, AuPt, and AuPd NPs with varying compositions and chemical orderings. By incorporating the modified BC model into an in-house-developed genetic algorithm (GA) we can effectively and accurately predict the most stable chemical orderings of large, realistic bimetallic NPs consisting of thousands of metal atoms. This is demonstrated on AuPd bimetallic NPs, a challenging system due to the similarity in the cohesion of the two metals. By training our BC model using a unique DFT calculation on a bimetallic NP (one calculation for two metals combining together), we expand to explore the chemical ordering of multimetallic NPs. We first demonstrate the application of our methodology on a AuPdPt NP and validate our stability predictions with literature data. Then, we effectively explore the vast materials space of multimetallic NPs consisting of combinations of Au, Pt, and Pd as a function of metal composition. Our thermodynamic stability trends are presented in a ternary diagram revealing detailed, and yet, unexpected chemical ordering trends. Our computational framework can aid both experimental and computational researchers toward effectively screening multimetallic NP stability. Moreover, we provide an outlook of how this framework can be applied to catalyst discovery, high-entropy alloys, and single-atom alloys.

Sequential galvanic replacement mediated Pd-doped hollow Ru-Te nanorods for enhanced hydrogen evolution reaction mass activity in alkaline media

High catalytic activity, long-term stability, and economical Pt-free catalysts for the hydrogen evolution reaction (HER) are required for the conversion of renewable energy systems. Noble nanomaterial Pt is a superior electrolysis catalyst for water splitting under typical experimental conditions with a relatively low overpotential. However, the use of Pt is limited by its high cost and activity degradation over time. Among several prospective alternatives, Ru has emerged as a promising alkaline electrolysis catalyst because of its significant catalytic activity and reduced cost compared to Pt. We designed and suggested Pd-doped hollow Ru-Te nanorods (PdRuTeNRs) via successive galvanic replacement reactions of sacrificial Te nanotemplates to further boost efficiency. The Pd/partially oxidized RuO₂/Ru/Te hetero-interfaced composition exhibited an HER mass activity of 11.3 A g^-1 Ru, twice that of Pt. In addition, the present PdRuTeNRs sufficiently maintained the activity from the 2000-cycle continuous test, greatly reducing the required cost by a quarter.

Porous aromatic frameworks with high Pd nanoparticles loading as efficient catalysts for the Suzuki coupling reaction

The development of efficient and recyclable heterogeneous Pd catalysts is an area of continuing attention due to their critical applications in organic synthesis and pharmaceutical production. In this study, two novel heterogeneous catalysts Pd@PAF-182 and Pd@PAF-183 were prepared by the immobilization/NaBH₄ reduction of PdCl₄^2- on hydrophilic cationic porous aromatic frameworks (PAF-182 and PAF-183), which were synthesized via a Yamamoto-type Ullmann coupling reaction from the corresponding aryl quaternary phosphonium salt monomer. Characterization by powder X-ray diffraction (PXRD), solid-state Cross-Polarization Magic-Angle-Spinning Nuclear Magnetic Resonance (CP/MAS NMR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) established the structures of the as-prepared catalysts. Inductively coupled plasma atomic emission spectrometry (ICP-AES) detection showed that the loading of Pd nanoparticles (Pd NPs) were 29.4 wt% for Pd@PAF-182 and 37.5 wt% for Pd@PAF-183, much higher than those of similar porous materials. Evaluation of the catalytic activity of the Pd@PAFs using Suzuki coupling as the model reaction demonstrated that as little as 0.12 mol% of Pd NPs could catalyze the Suzuki coupling with high efficiency, achieving yields up to 99% at 80 °C in 8 h. Recycling experiments also suggested that Pd@PAF-182 and Pd@PAF-183 maintained high catalytic activity with negligible leaching of Pd NPs after five cycles.

Assembly of Alloyed PdCu Nanosheets and Their Electrocatalytic Oxidation of Ethanol

Two-dimensional (2D) nanostructured catalysts have attracted great attention in many important fields, including energy applications and chemical industry. In this study, PdCu nanosheet assemblies (NSAs) have been synthesized and investigated as electrocatalysts for direct ethanol fuel cells in an alkaline medium. A great number of active sites on the nanosheets of PdCu NSAs for ethanol electro-oxidation are exposed, where the electron structures are optimized combined with the second element copper. Electrochemical measurements show that PdCu NSA1 exhibits excellent catalytic activity (2536 mA mg^-1) and cyclic stability compared to PdCu NSA2 (1700 mA mg^-1) and PdCu NSA3 (1436 mA mg^-1), much higher than commercial Pd/C. Kinetics studies on the electrolysis of ethanol suggest that PdCu NSAs should be more favorable at higher catalytic temperatures, higher concentrations of ethanol, and low pH value environments. The unique composition and structures PdCu NSA1 would result in the lowest energy barrier in the rate-controlling step of the ethanol oxidation reaction (EOR), confirmed by density functional theory (DFT). The formation mechanism of PdCu NSAs and their excellent electrocatalytic activity toward EOR have been discussed and analyzed.

Pt-Based Multimetal Electrocatalysts and Potential Applications: Recent Advancements in the Synthesis of Nanoparticles by Modified Polyol Methods

In our review, we have presented a summary of the research accomplishments of nanostructured multimetal-based electrocatalysts synthesized by modified polyol methods, especially the special case of Pt-based nanoparticles associated with increasing potential applications for batteries, capacitors, and fuel cells. To address the problems raised in serious environmental pollution, disease, health, and energy shortages, we discuss and present an improved polyol process used to synthesize nanoparticles from Pt metal to Pt-based bimetal, and Pt-based multimetal catalysts in the various forms of alloy and shell core nanostructures by practical experience, experimental skills, and the evidences from the designed polyol processes. In their prospects, there are the micro/nanostructured variants of hybrid Pt/nanomaterials, typically such as Pt/ABO3-type perovskite, Pt/AB2O4-type ferrite, Pt/CoFe2O4, Pt/oxide, or Pt/ceramic by modified polyol processes for the development of electrocatalysis and energy technology. In the future, we suggest that both the polyol and the sol-gel processes of diversity and originality, and with the use of various kinds of water, alcohols, polyols, other solvents, reducing agents, long-term capping and stabilizing agents, and structure- and property-controlling agents, are very effectively used in the controlled synthesis of micro/nanoparticles and micro/nanomaterials. It is understood that at the levels of controlling and modifying molecules, ions, atoms, and nano/microscales, the polyol or sol-gel processes, and their technologies are effectively combined in bottom-up and top-down approaches, as are the simplest synthetic methods of physics, chemistry, and biology from the most common aqueous solutions as well as possible experimental conditions.

Noble-metal-free single-phase Co3V2O8 with the structural integrity of nanofibers for the selective detection of ascorbic acid

Single-phase Co3V2O8 with the structural integrity of nanofiber exhibits high electrocatalytic activity for the oxidation of ascorbic acid (AA).

Ni–Fe nanoframes via a unique structural formation induced by sonochemical etching

A Ni–Fe nanoframe exhibits unique structural merits including 3D open structure and high surface area, enhancing electrochemical properties for oxygen-evolution reaction (OER).