Single Metal Nanoparticles Research Articles

Asymmetric Charge Distribution in Atomically Precise Metal Nanoclusters for Boosted CO2Reduction Catalysis.

Recently, atomically precise metal nanoclusters (NCs) have been widely applied in CO2 reduction reaction (CO2RR), achieving exciting activity and selectivity and revealing structure-performance correlation. However, at present, the efficiency of CO2RR is still unsatisfactory and cannot meet the requirements of practical applications. One of the main reasons is the difficulty in CO2 activation due to the chemical inertness of CO2. Constructing symmetry-breaking active sites is regarded as an effective strategy to promote CO2 activation by modulating electronic and geometric structure of CO2 molecule. In addition, in the subsequent CO2RR process, asymmetric charge distributed sites can break the charge balance in adjacent adsorbed C1 intermediates and suppress electrostatic repulsion between dipoles, benefiting for C-C coupling to generate C2+ products. Although compared to single atoms, metal nanoparticles, and inorganic materials the research on the construction of asymmetric catalytic sites in metal NCs is in a newly-developing stage, the precision, adjustability and diversity of metal NCs structure provide many possibilities to build asymmetric sites. This review summarizes several strategies of construction asymmetric charge distribution in metal NCs for boosting CO2RR, concludes the mechanism investigation paradigm of NCs-based catalysts, and proposes the challenges and opportunities of NCs catalysis.

Combination of nanoparticles with single-metal sites synergistically boosts co-catalyzed formic acid dehydrogenation

The development of hydrogen technologies is at the heart of a green economy. As prerequisite for implementation of hydrogen storage, active and stable catalysts for (de)hydrogenation reactions are needed. So far, the use of precious metals associated with expensive costs dominates in this area. Herein, we present a new class of lower-cost Co-based catalysts (Co-SAs/NPs@NC) in which highly distributed single-metal sites are synergistically combined with small defined nanoparticles allowing efficient formic acid dehydrogenation. The optimal material with atomically dispersed CoN2C2 units and encapsulated 7-8 nm nanoparticles achieves an excellent gas yield of 1403.8 mL·g−1·h−1 using propylene carbonate as solvent, with no activity loss after 5 cycles, which is 15 times higher than that of the commercial Pd/C. In situ analytic experiments show that Co-SAs/NPs@NC enhances the adsorption and activation of the key intermediate monodentate HCOO*, thereby facilitating the following C-H bond breaking, compared to related single metal atom and nanoparticle catalysts. Theoretical calculations show that the integration of cobalt nanoparticles elevates the d-band center of the Co single atoms as the active center, which consequently enhances the coupling of the carbonyl O of the HCOO* intermediate to the Co centers, thereby lowering the energy barrier.

Constructing ultralow-loading Cu single atoms/Fe2O3 particles on Nb2C MXenes for efficient utilization of atomic H to boost electrochemical debromination

Bromate is a commonly identified carcinogenic and genotoxic disinfection byproduct in water. Electrochemical debromination is an environmentally friendly and effective approach but it often suffers the limited reducing atomic H (H*) ability and high metal catalyst dosage. In this study, a unique composite catalyst comprised of ultra-low loading Cu single atoms (0.016 wt%) and Fe2O3 nanoparticles supported on a Nb2C MXene (denoted as Cu0.2/Fe0.1/Nb2C) was synthesized by one-step high-temperature molten salt method. The Cu0.2/Fe0.1/Nb2C significantly outperformed the Nb2C, Cu0.2/Nb2C and Fe0.1/Nb2C counterparts in the electrochemical debromination with a 94.2 % removal efficiency of bromate. It is revealed that the introducing of Cu single atoms, efficiently promotes the adsorption of H* and inhibition of competitive H2 evolution. The incorporation of Fe2O3 nanoparticles significantly increased the electronic metal-support interaction effect between the metal components and Nb2C, thereby forming a noticeable electronic cloud bridge to facilitate efficient charge transfer. Ultimately, the synergistic interplay between Cu single atoms and Fe2O3 nanoparticles plays a crucial role in achieving the remarkable removal performance of bromate. This work not only presents a significant instance of a synergistic catalyst involving metal single atoms and metal nanoparticles for effective electrochemical debromination but also advances the understanding of the electronic metal-support interaction.

Benchmark comparison study on metal single atom versus metal nanoparticle in photoredox catalysis: Which is better?

Reducing the size of metal nanoparticle (NP) cocatalyst down to single-atom level to improve photocatalytic efficiency is inevitably accompanied by the changes of its coordination environment, geometric configuration, electronic structure and active site. Thus, the construction of single metal atom (SA) photocatalyst is not necessarily a panacea for activity improvement toward target catalytic reactions. Herein, we report a critical and benchmark comparison in a reasonable framework of ZnIn2S4/Pt NP (ZIS/Pt NP) and ZnIn2S4/Pt SA (ZIS/Pt SA) towards photocatalytic hydrogen (H2) evolution, aiming to demonstrate which is better between Pt NP and Pt SA as cocatalyst in boosting photoredox catalysis. Mechanism study proves that the higher charge separation/transfer and weaker H* adsorption strength over ZIS/Pt NP than ZIS/Pt SA promote the more effective reduction of protons to H2, leading to the higher activity of ZIS/Pt NP than ZIS/Pt SA. Our work is expected to timely inspire the critical and rational thinking on the function and intrinsic mechanism of SA and NP cocatalysts in enhancing the photoredox catalysis performance.

Advancements in covalent organic framework‐based nanocomposites: Pioneering materials for CO2 reduction and storage

AbstractThe persistent increase in atmospheric carbon dioxide (CO2) concentration poses a significant contemporary challenge. Contemporary chemistry is heavily focused on sustainable solutions, particularly the photo‐/electrocatalytic reduction of CO2 and its utilization for energy storage. Despite promising prospects, efficient chemical CO2 conversion faces obstacles such as ineffective CO2 uptake/activation and catalyst mass transport. Covalent organic frameworks (COFs) have emerged as potential catalysts due to their precise structural design, functionalizable chemical environments, and robust architectures. COF‐based materials, especially those incorporating diverse active sites like single metal sites, metal nanoparticles, and metal oxides, hold promise for CO2 conversion and energy storage. This review sheds light on CO2 photoreduction/electroreduction and storage in Li‐CO2 batteries catalyzed by COF‐based composites, focusing on recent advancements in integrating COFs with nanoparticles for CO2 reduction. It discusses design principles, synthesis methods, and catalytic mechanisms driving the enhanced performance of COF‐based nanocomposites across various applications, including electrochemical reduction, photocatalysis, and lithium CO2 batteries. The review also addresses challenges and prospects of COF‐based catalysts for efficient CO2 utilization, aiming to steer the development of innovative COF‐based nanocomposites, thus advancing sustainable energy technologies and environmental stewardship. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

Well-defined high entropy-metal nanoparticles: Detection of the multi-element particles by deep learning

Characterizing and control the chemical compositions of multi-element particles as single metal nanoparticles (mNPs) on the surfaces of catalytic metal oxide supports is challenging. This can be attributed to the heterogeneity and large size at the nanoscale, the poorly defined catalyst nanostructure, and thermodynamic immiscibility of the strongly repelling metallic elements. To address these challenges, an ultrasonic-assisted coincident electro-oxidation-reduction-precipitation (U-SEO-P) is presented to fabricate ultra-stable PtRuAgCoCuP NPs, which produces numerous active intermediates and induces strong metal-support interactions. To sort the active high-entropy mNPs, individual NPs are described on the support surface and the role of deep learning in understanding/predicting the features of PtRuAgCoCu@TiOx catalysts is explained. Notably, this deep learning approach required minimal to no human input. The as-prepared PtRuAgCoCu@TiOx catalysts can be used to catalyze various important chemical reactions, such as a high reduction conversion (100% in 30 s), with no loss of catalytic activity even after 20 cycles of nitroarene and ketone/aldehyde, which is several times higher than commercial Pt@TiOx owing to individual PtRuAgCoCuP NPs on TiOx surface. In this study, we present the “Totally Defined Catalysis” concept, which has enormous potential for the advancement of high-activity catalysts in the reduction of organic compounds.

Multiple Fano Resonances Enabled by the Interference between an Out‐of‐Plane Plasmon Mode and Fabry–Pérot Cavity Modes

AbstractMultiple Fano resonances (mFRs) are arising as a promising optical platform to achieve precise sensing and detection. However, experimentally achieving mFRs by simple structures has remained challenging, which impedes the widespread applications of mFRs. Herein a simple structure composed of a single colloidal metal nanoparticle and a transition metal dichalcogenide flake to simultaneously achieve up to 8 FRs in experiments is demonstrated. Combining theoretical and experimental techniques, that an out‐of‐plane plasmon mode of the metal nanoparticle interferes with the Fabry–Pérot cavity modes from the WS2 flake to form mFRs in the visible region is proved. The simplicity and generality of the method further allow us to systematically study the tunability of the mFRs, in terms of the peak/dip positions and the number of FRs, by changing the structural parameters, which include the thickness of the WS2 flake, size and shape of the plasmonic nanoparticle. In addition, the quality of the mFRs is proved to be adjustable by tuning the reflectivity of the substrate in the system. The highest quality factor and spectral contrast of the achieved resonances are up to ≈180 and ≈0.95, respectively. The simple structure and high‐quality optical modes will prosper applications in precise sensing and light modulation.

Large-scale SU-8 Micro-Pole-Arrays decorated with Hierarchical Metal-Dielectric-Metal nanostructures as sensitive 3D SERS substrates

Dielectric layer-mediated surface-enhanced Raman scattering (SERS) substrates are currently explored for ultrasensitive detection and expected to provide uniform SERS response by the virtue of three-dimensional micro-nanostructures, dielectric layer, and plasmonic metal nanostructures. For this purpose, the present work reports on the development of the metal-dielectric-metal (MDM) three-dimensional (3D) micro-pole-arrays structure based on SU-8 colloid lithography. By utilizing the large-scale periodic arrangement characteristics of SU-8 colloidal lithography, along with the hot spot effect created by the nano-gap between MDM, we successfully prepared an array of SERS substrates that exhibit both periodicity and multi-dimensional plasmonic coupling effect. Compared to a single metal nanoparticle substrate, the SERS activity of the substrate is significantly enhanced, and the substrate has trace detection ability (LOD of detection of 10−12 mol/L for R6G). The enhancement factor (EF) is 5.72 × 107. Periodicity ensures that the prepared substrate has good reproducibility (RSD < 8 %) and stability. Furthermore, the substrate modified with HS-β-CD demonstrated potential for rapid trace SERS detection of polychlorinated biphenyls (PCB-77) (LOD of 10−8 mol/L for PCB-77). The results indicate that the proposed substrate has the potential for application in the preparation of SERS sensors with high sensitivity and uniformity.

Poplar wood treated with nano-silver–copper particles: fungal degradation and leaching analysis

Abstract This study investigated the inhibition effect of nanoscale silver–copper particle (20 nm) against Coriolus versicolor and Gloeophyllum trabeum. Poplar wood samples (Populus L.) were vacuum-impregnated using aqueous nano-AgCu solutions at concentrations of 0.01 %, 0.02 %, 0.03 %, 0.05 %, 0.075 %, and 0.1 %. Alkaline copper quaternary (ACQ, 0.1 %), boric acid (0.2 %) and untreated control group (CK) were employed for comparisons. Decay resistance and leachability were studied. The anti-fungi effects were compared between nano-AgCu, nano-Ag, Ag+ (silver nitrate), Cu2+ (copper nitrate), and a composite of Ag+–Cu2+. Nano-AgCu particle exhibited effective resistance to fungi after 12 weeks of exposure. The threshold retention of the nano-AgCu against C. versicolor and G. trabeum on poplar wood was 0.19 kg m−3 and 0.62 kg m−3, respectively. The silver–copper nanoparticles demonstrated excellent leach resistance, and the inhibition effect was retained after leaching. The nano-AgCu particle provided better antifungal effects than single ions or metal nanoparticles. This study illustrates the potential of using nano-AgCu particle as an efficient wood preservative compared to commercial water-soluble preservatives.

Selective and Accurate Detection of Nitrate in Aquaculture Water with Surface-Enhanced Raman Scattering (SERS) Using Gold Nanoparticles Decorated with β-Cyclodextrins.

A surface-enhanced Raman scattering (SERS) method for measuring nitrate nitrogen in aquaculture water was developed using a substrate of β-cyclodextrin-modified gold nanoparticles (SH-β-CD@AuNPs). Addressing the issues of low sensitivity, narrow linear range, and relatively poor selectivity of single metal nanoparticles in the SERS detection of nitrate nitrogen, we combined metal nanoparticles with cyclodextrin supramolecular compounds to prepare a AuNPs substrate enveloped by cyclodextrin, which exhibits ultra-high selectivity and Raman activity. Subsequently, vanadium(III) chloride was used to convert nitrate ions into nitrite ions. The adsorption mechanism between the reaction product benzotriazole (BTAH) of o-phenylenediamine (OPD) and nitrite ions on the SH-β-CD@AuNPs substrate was studied through SERS, achieving the simultaneous detection of nitrate nitrogen and nitrite nitrogen. The experimental results show that BTAH exhibits distinct SERS characteristic peaks at 1168, 1240, 1375, and 1600 cm-1, with the lowest detection limits of 3.33 × 10-2, 5.84 × 10-2, 2.40 × 10-2, and 1.05 × 10-2 μmol/L, respectively, and a linear range of 0.1-30.0 μmol/L. The proposed method provides an effective tool for the selective and accurate online detection of nitrite and nitrate nitrogen in aquaculture water.

Enhanced room-temperature hydrogen storage by CuNi nanoparticles decorated in metal-organic framework UiO-66(Zr)

This study demonstrates the significant effect of incorporating inexpensive transition metal nanoparticles into metal-organic frameworks (MOFs) to improve their room-temperature hydrogen storage properties. Low-cost nanoparticles (Cu, Ni, and CuNi) were incorporated into UiO-66(Zr) via the double-solvent approach (DSA) plus chemical reduction processes. All composites exhibited higher hydrogen storage capacity compared to pure UiO-66 at both room temperature and 60 bar. Notably, the hydrogen spillover efficiency of CuNi nanoparticles loaded in UiO-66 was comparable to that of MOF adsorbents embedded with noble metals such as Pd and Pt. The hydrogen storage capacity of CuNi@UiO-66 was significantly increased from 0.20 wt% to 0.74 wt%. DFT calculations showed that the CuNi alloys facilitated the adsorption and dissociation of hydrogen molecules in comparison to the single metal nanoparticles, thus favoring the hydrogen spillover effect and improving the hydrogen storage performance. This work demonstrates the potential of designing MOF loaded with inexpensive metal nanoparticles for optimized room-temperature hydrogen storage.

Heating of nanoparticles and their environment by laser radiation and applications

This review considers the fundamental dynamic processes involved in the laser heating of metal nanoparticles and their subsequent cooling. Of particular interest are the absorption of laser energy by nanoparticles, the heating of a single nanoparticle or an ensemble thereof, and the dissipation of the energy of nanoparticles due to heat exchange with the environment. The goal is to consider the dependences and values of the temperatures of the nanoparticles and the environment, their time scales, and other parameters that describe these processes. Experimental results and analytical studies on the heating of single metal nanoparticles by laser pulses are discussed, including the laser thresholds for initiating subsequent photothermal processes, how temperature influences the optical properties, and the heating of gold nanoparticles by laser pulses. Experimental studies of the heating of an ensemble of nanoparticles and the results of an analytical study of the heating of an ensemble of nanoparticles and the environment by laser radiation are considered. Nanothermometry methods for nanoparticles under laser heating are considered, including changes in the refractive indices of metals and spectral thermometry of optical scattering of nanoparticles, Raman spectroscopy, the thermal distortion of the refractive index of an environment heated by a nanoparticle, and thermochemical phase transitions in lipid bilayers surrounding a heated nanoparticle. Understanding the sequence of events after radiation absorption and their time scales underlies many applications of nanoparticles. The application fields for the laser heating of nanoparticles are reviewed, including thermochemical reactions and selective nanophotothermolysis initiated in the environment by laser-heated nanoparticles, thermal radiation emission by nanoparticles and laser-induced incandescence, electron and ion emission of heated nanoparticles, and optothermal chemical catalysis. Applications of the laser heating of nanoparticles in laser nanomedicine are of particular interest. Significant emphasis is given to the proposed analytical approaches to modeling and calculating the heating processes under the action of a laser pulse on metal nanoparticles, taking into account the temperature dependences of the parameters. The proposed models can be used to estimate the parameters of lasers and nanoparticles in the various application fields for the laser heating of nanoparticles.

Advance in Detection Technique of Lean Meat Powder Residues in Meat Using SERS: A Review.

Food that contains lean meat powder (LMP) can cause human health issues, such as nausea, headaches, and even death for consumers. Traditional methods for detecting LMP residues in meat are often time-consuming and complex and lack sensitivity. This article provides a review of the research progress on the use of surface-enhanced Raman spectroscopy (SERS) technology for detecting residues of LMP in meat. The review also discusses several applications of SERS technology for detecting residues of LMP in meat, including the enhanced detection of LMP residues in meat based on single metal nanoparticles, combining metal nanoparticles with adsorbent materials, combining metal nanoparticles with immunizing and other chemicals, and combining the SERS technology with related techniques. As SERS technology continues to develop and improve, it is expected to become an even more widely used and effective tool for detecting residues of LMP in meat.

Antimicrobial Activity of Biogenic Metal Oxide Nanoparticles and Their Synergistic Effect on Clinical Pathogens.

The rising prevalence of antibiotic-resistance is currently a grave issue; hence, novel antimicrobial agents are being explored and developed to address infections resulting from multiple drug-resistant pathogens. Biogenic CuO, ZnO, and WO3 nanoparticles can be considered as such agents. Clinical isolates of E. coli, S. aureus, methicillin-resistant S. aureus (MRSA), and Candida albicans from oral and vaginal samples were treated with single and combination metal nanoparticles incubated under dark and light conditions to understand the synergistic effect of the nanoparticles and their photocatalytic antimicrobial activity. Biogenic CuO and ZnO nanoparticles exhibited significant antimicrobial effects under dark incubation which did not alter on photoactivation. However, photoactivated WO3 nanoparticles significantly reduced the number of viable cells by 75% for all the test organisms, thus proving to be a promising antimicrobial agent. Combinations of CuO, ZnO, and WO3 nanoparticles demonstrated synergistic action as a significant increase in their antimicrobial property (>90%) was observed compared to the action of single elemental nanoparticles. The mechanism of the antimicrobial action of metal nanoparticles both in combination and in isolation was assessed with respect to lipid peroxidation due to ROS (reactive oxygen species) generation by measuring malondialdehyde (MDA) production, and the damage to cell integrity using live/dead staining and quantitating with the use of flow cytometry and fluorescence microscopy.

Experimental and theoretical investigation of high-entropy-alloy/support as a catalyst for reduction reactions

Control of chemical composition and incorporation of multiple metallic elements into a single metal nanoparticle (NP) in an alloyed or a phase-segregated state hold potential scientific merit; however, developing libraries of such structures using effective strategies is challenging owing to the thermodynamic immiscibility of repelling constituent metallic elements. Herein, we present a one-pot interfacial plasma–discharge-driven (IP-D) synthesis strategy for fabricating stable high-entropy-alloy (HEA) NPs exhibiting ultrasmall size on a porous support surface. Accordingly, an electric field was applied for 120 s to enhance the incorporation of multiple metallic elements (i.e., CuAgFe, CuAgNi, and CuAgNiFe) into ally HEA-NPs. Further, NPs were attached to a porous magnesium oxide surface via rapid cooling. With solar light as the sole energy input, the CuAgNiFe catalyst was investigated as a reusable and sustainable material exhibiting excellent catalytic performance (100% conversion and 99% selectivity within 1 min for a hydrogenation reaction) and consistent activity even after 20 cycles for a reduction reaction, considerably outperforming the majority of the conventional photocatalysts. Thus, the proposed strategy establishes a novel method for designing and synthesizing highly efficient and stable catalysts for the convertion of nitroarenes to anilines via chemical reduction.

Photoinduced Charge Transfer and Trapping on Single Gold Metal Nanoparticles on TiO2

Photoinduced Charge Transfer and Trapping on Single Gold Metal Nanoparticles on TiO2

New fabrication of nonmodel supported catalysts for cellulose to low carbon chemicals with the assistance of mechanochemical abrading

The controllable conversion of cellulose on heterogeneous catalysts is a promising strategy in biomass utilization. However, the catalysts in this field are fabricated by a conventional, calcination/hydrothermal method, both of which are time-consuming, high cost and limit their large-scale applications. In this study, we developed the mechanical force as an auxiliary method to fabricate nonmodel supported catalyst with the assistance of chitosan (CTS). The input kinetic energy facilitated strain refinement and microstructure defects generation by shear force and plastic deformations, which stimulated the metal precursors anchored in situ in the CTS matrix. Based on the interactions between metals (Ni and Sn) and nitrogen atoms, the single metal nanoparticles and intermetallic compounds (NixSny) were well dispersed with 152 μmol/g of Lewis acid and 91 μmol/g of base amount by interaction with nitrogen sites. 62.8% of C2,3 polyols were obtained from cellulose on 15%Ni–15%W/CTS catalyst. More importantly, this catalyst prepared by mechanochemical abrading demonstrated perfect stability with less than 2.0 ppm of etched metal cations for the eighth use in acidic hydrothermal conditions. In accordance, the nitrogen sites in the carbon matrix offered strong covalent bonds regarding as anchoring rope for stabilizing Ni species. This work potentially offers a facile but effective method for the development of supported Ni–Sn catalysts with possible large-scale production.

Understanding the nanoscale interactions of surface plasmon-mediated semiconductor surfaces with water and light for renewable energy harvesting and conversion

Photocatalysts integrated with surface plasmon metals serve as an interesting platform for fully understanding how energy harvesting and storage are managed through physical and chemical enhancement processes. Nanoelectrode with a single plasmon metal nanoparticle (NP) provides unique features capable of resolving complex enhancement processes which otherwise cannot be achievable through conventional ensemble averaging methods. Preliminary theoretical results are presented here to illustrate both electrochemical and optical field enhancement characteristics of a single NP when interacting with a semiconductor surface. Potential methodologies to construct single plasmon nanoelectrodes and challenges are discussed in this opinion.

Enhanced thermophysical properties of water-based single and hybrid metallic nanofluids: Insights from Equilibrium Molecular Dynamics

The effect of single (Cu or Ag) and hybrid (Cu+Ag) metallic nanoparticles on the thermophysical properties, namely viscosity and thermal conductivity of water-based nanofluids, has been studied using Equilibrium Molecular dynamics (EMD) simulation. The TIP3P (three-site transferrable intermolecular potential) water model has been chosen. The interaction of water molecules has been modelled by the Lennard-Jones (L J) potential in combination with Coulomb potential. The embedded-atom (EAM) potential method has been used for hybrid (Cu and Ag) atom interaction. Simulation has been performed at 303 K and atmospheric pressure using the Berendsen algorithm under NVT (constant number, constant volume, and constant temperature) ensemble with production steps of 2 ns and integral step of 1fs. Interestingly, nanofluids containing one metallic nanoparticle (Cu or Ag) have lower thermal conductivity and viscosity than nanofluids having hybrid metallic nanoparticles with the same volume fraction.

Plasmonic-Thermoelectric Nanotweezers for Immersive SERS Mapping.

Surface-enhanced Raman spectroscopy (SERS) technology usually uses metallic nanoparticles to enhance Raman scattering signals, thereby significantly adding to molecule-level recognition and detection. However, realization of nanometer-scaled SERS imaging in liquid environments is extremely difficult due to the requirements of both precise scanning of single metallic nanoparticle and high enhancement field and thus has never been achieved before. To overcome this obstacle, we demonstrate an immersive nanometer-scaled SERS mapping technology, based on dynamic scanning of a single metallic nanoparticle with a plasmonic-thermoelectric nanotweezers system. The technology offers greater stability in the plasmonic trapping of gold nanoparticles at relative low power, as well as generating higher electric fields in the gap region. Through its dynamics, two-dimensional nanometer-scaled SERS imaging is achieved successfully. In regard to in liquid environments, this technology provides a mapping method for label-free imaging of ultrathin materials, structures, and biological samples.