Capping Ligands Research Articles

Palladium cluster complex [Pd13(μ4-C7H7)6]2+ (C7H7 = tropylium) with an fcc-close-packed cuboctahedral Pd13 core and isomers: theoretical insight into ligand-control of the Pd13 core structure.

One of the challenging targets in today's chemistry is size-, shape- and metal-atom packing-controlled synthesis of nano-scale transition metal cluster complexes because key factors governing these features have been elusive. Here, we present a DFT study on a recently synthesized palladium cluster complex [Pd13(μ4-C7H7)6]2+ (named Cubo-μ4; C7H7 = tropylium) with an fcc-close-packed cuboctahedral Pd13 core and possible isomers. The stability decreases in the order Cubo-μ4 > [Pd13(μ3-C7H7)3(μ4-C7H7)3]2+ with an hcp-close-packed anticuboctahedral Pd13 core (Anti-μ3,4) > [Pd13(μ3-C7H7)6]2+ with a non-close packed icosahedral Pd13 core (Ih-μ3) > [Pd13(μ4-C7H7)6]2+ with an anticuboctahedral Pd13 core (Anti-μ4) > [Pd13(μ3-C7H7)6]2+ with a cuboctahedral Pd13 core (Cubo-μ3). This ordering disagrees with the stability of the Pd13 core. The key factor governing the stability and metal-atom packing manner of these Pd13 cluster complexes is not the stability of the Pd13 core but the interaction energy between the Pd13 core and the [(C7H7)6]2+ ligand shell. The interaction energy is mainly determined by the charge-transfer from the Pd13 core to the [(C7H7)6]2+ ligand shell and the coordination mode of the C7H7 ligand (μ3- vs. μ4-coordination bond). In the μ4-coordination, all seven C atoms of the C7H7 ligand interact with four Pd atoms of the Pd4 plane using two CC double bonds and one π-allyl moiety. On the other hand, in the μ3-coordination, one or two C atoms of C7H7 cannot form bonding interaction with the Pd atom of the Pd3 plane. Thus, the use of appropriate capping ligands is one of the key points in the synthesis of nano-scale metal cluster complexes.

Post-synthetic modification of semiconductor nanoparticles can generate lanthanide luminophores and modulate the electronic properties of preformed nanoparticles

Post-synthetic modification of inorganic nanoparticles (NPs) provides a unique lesser synthetically demanding opportunity to access nanomaterials those are oftentimes not directly realizable by conventional synthetic routes. Trivalent lanthanide (Ln3+) incorporated (doped) semiconductor NPs can benefit from individual properties of the NPs and Ln3+ moieties. This work summarizes key outcomes from experiments when (a) ZnS /CdS /CdSe NPs are post-synthetically treated with Ln3+ to generate ZnS/Ln or CdSe/Ln [Ln = Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb] and CdS/Ln [Eu, Tb] NPs, (b) synthetically Tb3+ doped Zn(Tb)S NPs are post-synthetically modified with varying concentration of heavy metals like Pb2+/Cd2+ to generate Zn(Tb)S/M [M = Pb, Cd] NPs, and (c) the pH of Zn(Tb)S NPs aqueous dispersion is varied post-synthetically. Key observations from these experiments include (a) incorporation of Ln in all the post-synthetically prepared CA/Ln NPs, with presence of host sensitized dopant emission in select cases that can be rationalized by a charge trapping mediated dopant emission sensitization processes, (b) existence of rich photophysics in the sub-stoichiometric reactant concentration ratio, and (c) identifying the alteration of surface capping ligand structure as an important variable to control the Ln3+ emission. In summary, these experimental observations provide an easy control of reaction conditions either to generate Ln3+ inorganic NP luminophores or to control their electronic properties by modulating either the NP’s core or surface properties, and are of potential usefulness in various luminescence based applications.

Impact of core-shell perovskite nanocrystals for LED applications: successes, challenges, and prospects.

Perovskite nanocrystals (PeNCs) synthesized by colloidal solution methods are an outstanding case of study due to their remarkable optical features, different from their bulk counterpart, such as a tuneable band gap and narrower photoluminescence emission, altered by the size and shape. However, the stability of these systems needs to be improved to consolidate their application in optoelectronic devices. Improved PeNC quality is associated with a less defective structure, as it affects negatively the photoluminescence quantum yield (PLQY), due to the essential, but at the same time labile interaction between the colloidal capping ligands and the perovskite core. In this sense, it would be extremely effective to obtain an alternative method to stabilize the PeNC phases and passivate the surface, in order to improve both stability and optical properties. This objective can be reached exploiting the structural benefits of the interaction between the perovskite and other organic or inorganic materials with a compatible structure and optical properties and limiting the optical drawbacks. This perspective contemplates different combinations of core/shell PeNCs and the critical steps during the synthesis, including drawbacks and challenges based on their optical properties. Additionally, it provides insights for future light emitting diode (LED) applications and advanced characterization. Finally, the existing challenges and opportunities for core/shell PeNCs are discussed.

Unraveling chemical processes during nanoparticle synthesis with liquid phase electron microscopy and correlative techniques.

Liquid phase transmission electron microscopy (LPTEM) has enabled unprecedented direct real time imaging of physicochemical processes during solution phase synthesis of metallic nanoparticles. LPTEM primarily provides images of nanometer scale, and sometimes atomic scale, metal nanoparticle crystallization processes, but provides little chemical information about organic surface ligands, metal-ligand complexes and reaction intermediates, and redox reactions. Likewise, complex electron beam-solvent interactions during LPTEM make it challenging to pinpoint the chemical processes, some involving exotic highly reactive radicals, impacting nanoparticle formation. Pairing LPTEM with correlative solution synthesis, ex situ chemical analysis, and theoretical modeling represents a powerful approach to gain a holistic understanding of the chemical processes involved in nanoparticle synthesis. In this feature article, we review recent work by our lab and others that has focused on elucidating chemical processes during nanoparticle synthesis using LPTEM and correlative chemical characterization and modeling, including mass and optical spectrometry, fluorescence microscopy, solution chemistry, and reaction kinetic modeling. In particular, we show how these approaches enable investigating redox chemistry during LPTEM, polymeric and organic capping ligands, metal deposition mechanisms on plasmonic nanoparticles, metal clusters and complexes, and multimetallic nanoparticle formation. Future avenues of research are discussed, including moving beyond electron beam induced nanoparticle formation by using light and thermal stimuli during LPTEM. We discuss prospects for real time LPTEM imaging and online chemical analysis of reaction intermediates using microfluidic flow reactors.

Charge Carrier Dynamics of CsPbBr3/g-C3N4 Nanoheterostructures in Visible-Light-Driven CO2-to-CO Conversion

The photon energy-dependent selectivity of photocatalytic CO2-to-CO conversion by CsPbBr3 nanocrystals (NCs) and CsPbBr3/g-C3N4 nanoheterostructures (NHSs) was demonstrated for the first time. The surficial capping ligands of CsPbBr3 NCs would adsorb CO2, resulting in the carboxyl intermediate to process the CO2-to-CO conversion via carbene pathways. The type-II energy band structure at the heterojunction of CsPbBr3/g-C3N4 NHSs would separate the charge carriers, promoting the efficiency in photocatalytic CO2-to-CO conversion. The electron consumption rate of CO2-to-CO conversion for CsPbBr3/g-C3N4 NHSs was found to intensively depend on the rate constant of interfacial hole transfer from CsPbBr3 to g-C3N4. An in situ transient absorption spectroscopy investigation revealed that the half-life time of photoexcited electrons in optimized CsPbBr3/g-C3N4 NHS was extended two times more than that in the CsPbBr3 NCs, resulting in the higher probability of charge carriers to carry out the CO2-to-CO conversion. The current work presents important and novel insights of semiconductor NHSs for solar energy-driven CO2 conversion.

Node Distortion as a Tunable Mechanism for Negative Thermal Expansion in Metal–Organic Frameworks

Chemically functionalized series of metal-organic frameworks (MOFs), with subtle differences in local structure but divergent properties, provide a valuable opportunity to explore how local chemistry can be coupled to long-range structure and functionality. Using in situ synchrotron X-ray total scattering, with powder diffraction and pair distribution function (PDF) analysis, we investigate the temperature dependence of the local- and long-range structure of MOFs based on NU-1000, in which Zr6O8 nodes are coordinated by different capping ligands (H2O/OH, Cl- ions, formate, acetylacetonate, and hexafluoroacetylacetonate). We show that the local distortion of the Zr6 nodes depends on the lability of the ligand and contributes to a negative thermal expansion (NTE) of the extended framework. Using multivariate data analyses, involving non-negative matrix factorization (NMF), we demonstrate a new mechanism for NTE: progressive increase in the population of a smaller, distorted node state with increasing temperature leads to global contraction of the framework. The transformation between discrete node states is noncooperative and not ordered within the lattice, i.e., a solid solution of regular and distorted nodes. Density functional theory calculations show that removal of ligands from the node can lead to distortions consistent with the Zr···Zr distances observed in the experiment PDF data. Control of the node distortion imparted by the nonlinker ligand in turn controls the NTE behavior. These results reveal a mechanism to control the dynamic structure of MOFs based on local chemistry.

Effect of hydrophobic silica aerogels in-situ on encapsulation the stability of CsPbBr3 quantum dots for white light-emitting diodes

Despite the outstanding optical features of lead halide perovskite quantum dots (QDs), they are troubled by stability issues that hinder their prospects in practical applications. Herein, the CsPbBr3 QDs generated here were grown in situ in hydrophobic silica aerogels (SiO2 AGs). More importantly, the photoinitiated cross-linking reaction of the capping ligands, conjugated linoleic acids (CLA), forms hydrophobic polymer shells from CsPbBr3 QDs@SiO2 AGs-poly. And these polymer shells further improve the water stability of QDs. The composite retains 83 % photoluminescence (PL) intensity after being dispersed in water for five days. And SiO2 AGs also act as confined templates owing to their unique porous structure to avoid aggregation and regrowth of QDs in the polymerization process of CLA. With the combined effects of SiO2 AGs and polymer shells, the composite shows remarkable optical performance with a high absolute quantum yield (QY) (89.08 %). And this green-emitting composite was applied as a luminescent material in a white light-emitting diode (WLED), which exhibited excellent luminescence with the color coordinates of (0.3344, 0.3253) and light efficiency of 28.8 lm/W at 20 mA, and light stability under large current.

Aggregation induced emission of surface ligand controlled gold nanoclusters employing imidazolium surface active ionic liquid and pH sensitivity

Gold nanoclusters (AuNCs) are one of the emerging materials due to their luminescence property, but their fluorescence intensity significantly gets quenched in aqueous medium due to the intramolecular vibration and rotation of the capping ligands. Herein, we have prepared long carbon chain containing mercaptan acids capped AuNCs, using 16-mercaptohexadecanoic acid (MHDA) and 11-mercaptoundecanoic acid (MUA) respectively, in aqueous medium with quantum yields (QYs) 3.01% and 6.27% respectively. These AuNCs are negatively charged particles confirmed by zeta potential measurements. After addition of positively charged long hydrocarbon chain containing imidazolium surface active ionic liquid (SAIL), 1-hexadecyl-3-methylimidazolium chloride (C16mimCl) in these aqueous AuNCs solutions, respective fluorescence intensities increase due to the formation of rigid aggregates with AuNC. The intramolecular vibration and rotation of these capping ligands (MHDA and MUA) are reduced due to the formation of these rigid aggregates and therefore, the QYs of these MHDA and MUA capped AuNCs increase to 5.78% and 6.87% respectively. Now the aggregation induced emission is strongly dependent on the concentration of added C16mimCl with the presence of three distinct regions (first turbid, precipitate and second turbid). The aggregation induced emission enhancement in case of MHDA capped AuNC becomes more prominent than MUA capped AuNC because of more hydrophobic interaction. Moreover, with decreasing the pH of the solution, the carboxylate (–COO-) groups of the capping ligands are protonated and therefore, the electrostatic interaction between AuNCs and C16mimCl no longer exist. This results the gradual decrement in emission intensity and this produces a linear relationship against pH of the solution within pH range 7.5 to 1.5.

Mixed halide perovskite nanocrystals with surface engineering based on pseudohalide passivation and Short-Chain ligand exchange for High-Performance blue Light-Emitting diodes

Perovskite nanocrystals (PeNCs) have attracted considerable interest in light-emitting diodes (LEDs) owing to their unique optoelectronic properties. Although significant progress has been made in green and red perovskite LEDs (PeLEDs) with PeNCs, the performance of blue PeLEDs is still limited. The main obstacles for blue PeLEDs based on PeNCs are their Cl vacancy-induced low quantum efficiency in mixed halide (Br/Cl) systems and high electrical resistance from long organic capping ligands. In this study, to overcome these issues and achieve high-performance blue PeLEDs, a surface engineering (SE) strategy based on pseudohalide defect passivation and short-chain ligand exchange was introduced. By passivating Cl vacancies with SCN– and exchanging long-chain oleic acid and oleylamine ligands with short octylphosphonic acid and 3,3-diphenylpropyl amine, respectively, the optoelectronic properties of the PeNCs were significantly enhanced. The blue PeLEDs based on PeNCs, using SE, exhibited a maximum luminance of 1874 cd/m2 and maximum external quantum efficiency of 4.9 % at an electroluminescence wavelength of 467 nm, which satisfies the blue primary color requirement (467 nm) in Rec. 2020 color space.

Synthesis and Properties of Stable Amino Metal Halide Molecular Clusters in the Solid State.

Nanosized molecular clusters (MCs) composed of PbBr2 and neutral ligand butylamine (BTYA) with unique optical properties in solution and solid states have been synthesized using ligand-assisted reprecipitation and spin-coating, separately. The studies of their optical properties using ultraviolet-visible (UV-vis) absorption and photoluminescence (PL) show the first electronic absorption and PL band of the MCs at 401 and 411 nm, respectively, for the solution and solid state samples that exhibit good stability under ambient conditions. Low-temperature PL spectra below 30 K show vibronic peaks indicative of a single size or a very narrow size distribution of the MCs. On the basis of Raman, X-ray diffraction, and transmission electron microscopy measurements, a layered structural model is proposed for the MCs with a BTYA ligand capping on the surface of the corner-shared tilted [PbBr6]4- octahedral framework. The stable and retained structure of MCs in the solid state is promising for photonics applications.

Functionalized Silver and Gold Nanomaterials with Diagnostic and Therapeutic Applications.

The functionalization of nanomaterials with suitable capping ligands or bioactive agents is an interesting strategy in designing nanosystems with suitable applicability and biocompatibility; the physicochemical and biological properties of these nanomaterials can be highly improved for biomedical applications. In this context, numerous explorations have been conducted in the functionalization of silver (Ag) and gold (Au) nanomaterials using suitable functional groups or agents to design nanosystems with unique physicochemical properties such as excellent biosensing capabilities, biocompatibility, targeting features, and multifunctionality for biomedical purposes. Future studies should be undertaken for designing novel functionalization tactics to improve the properties of Au- and Ag-based nanosystems and reduce their toxicity. The possible release of cytotoxic radicals or ions, the internalization of nanomaterials, the alteration of cellular signaling pathways, the translocation of these nanomaterials across the cell membranes into mitochondria, DNA damages, and the damage of cell membranes are the main causes of their toxicity, which ought to be comprehensively explored. In this study, recent advancements in diagnostic and therapeutic applications of functionalized Au and Ag nanomaterials are deliberated, focusing on important challenges and future directions.

Hydrogen generation of single alloy Pd/Pt quantum dots over Co3O4 nanoparticles via the hydrolysis of sodium borohydride at room temperature

To satisfy global energy demands and decrease the level of atmospheric greenhouse gases, alternative clean energy sources are required. Hydrogen is one of the most promising clean energy sources due to its high chemical energy density and near-zero greenhouse gas emissions. A single alloyed phase of Pd/Pt nanoclusters as quantum dots (QDs) was prepared and loaded over Co3O4 nanoparticles with a low loading percentage (1 wt.%) for hydrogen generation from the hydrolysis of NaBH4 at room temperature. L-glutathione (SG) was used as a capping ligand. It was found that the single alloy catalyst (Pd0.5–Pt0.5)n(SG)m/Co3O4 caused a significant enhancement in hydrogen generation in comparison to the monometallic clusters (Pdn(SG)m and Ptn(SG)m). Moreover, the Pd/Pt alloy showed a positive synergistic effect compared to the physical mixture of Pd and Pt clusters (1:1) over Co3O4. The QDs alloy and monometallic Pd and Pt clusters exhibited well-dispersed particle size in ~ 1 nm. The (Pd0.5–Pt0.5)n(SG)m)/Co3O4 catalyst offers a high hydrogen generation rate (HGR) of 8333 mL min− 1 g− 1 at room temperature. The synergistic effect of Pd and Pt atoms in the nanoclusters alloy is the key point beyond this high activity, plus the prepared clusters' unique atomic packing structure and electronic properties. The effect of the NaBH4 concentration, catalyst amount, and reaction temperature (25–60 °C) were investigated, where HGR reaches 50 L min− 1 g− 1 at 60 °C under the same reaction conditions. The prepared catalysts were analyzed by UV–Vis, TGA, HR-TEM, XRD, and N2 adsorption/desorption techniques. The charge state of the Pd and Pt in monometallic and alloy nanoclusters is zero, as confirmed by X-ray photoelectron spectroscopy analysis. The catalysts showed high recyclability efficiency for at least five cycles due to the high leaching resistance of the alloy nanoclusters within the Co3O4 host. The prepared catalysts are highly efficient for energy-based applications.

DNA‐Encoded Nanomaterials with Controllable Properties

AbstractDNA as an attractive capping ligand or template has been extensively utilized for synthesizing nanomaterials, and fabricating nano‐systems with tuneable properties. This review aims to summarize related significant progress on DNA‐encoded nanomaterials and their controllable properties including catalysis, surface plasmon resonance, chirality, surface‐enhanced Raman scattering and fluorescence, moreover, to present the underlying clues to engineer nanomaterials with DNA on the basis of DNA‐metal ion and DNA‐nanomaterial interactions. The apparent utility of diverse DNA modules including DNA homopolymers (e. g., poly adenine), secondary structures (e. g., triplex) and DNA nanostructures (e. g., DNA origami), etc., is revealed, which is derived from their strong specific interactions, stimulus‐responsive features, or excellent addressable functions, etc. Accompanied by insight into the underlying mechanism of DNA‐participated interactions, it is anticipated that, new DNA‐encoded nanomaterials will be reported and contribute to exploration of intelligent nanocatalysts, nanoprobes and nanomedicines.

Achieving High Photo/Thermocatalytic Product Selectivity and Conversion via Thorium Clusters with Switchable Functional Ligands.

Structural exploration and functional application of thorium clusters are still very rare on account of their difficult synthesis caused by the susceptible hydrolysis of thorium element. In this work, we elaborately designed and constructed four stable thorium clusters modified with different functionalized capping ligands, Th6-MA, Th6-BEN, Th6-C8A, and Th6-Fcc, which possessed nearly the same hexanuclear thorium-oxo core but different capabilities in light absorption and charge separation. Consequently, for the first time, these new thorium clusters were treated as model catalysts to systematically investigate the light-induced oxidative coupling reaction of benzylamine and thermodriven oxidation of aniline, achieving >90% product selectivity and approximately 100% conversion, respectively. Concurrently, we found that thorium clusters modified by switchable functional ligands can effectively modulate the selectivity and conversion of catalytic reaction products. Moreover, catalytic characterization and density functional theory calculations consistently indicated that these thorium clusters can activate O2/H2O2 to generate active intermediates O2·-/HOO· and then improved the conversion of amines efficiently. Significantly, this work represents the first report of stable thorium clusters applied to photo/thermotriggered catalytic reactions and puts forward a new design avenue for the construction of more efficient thorium cluster catalysts.

29.3: Perovskite‐Oxide Heteronanocrystals for Light Emitting Application

Colloidal lead halide Perovskite nanocrystals (PNCs) have excellent optical properties that endow the PNCs with great application advantages in the display field. However, the ionic surface structure makes PNCs easy to degrade in light, heat, and air, which restricts their application. Here we report ligand-induced growth of crystalline ZnO on CsPbX3 (X = Br, I) PNCs for LED application based on the design of PNCs with carboxylate ligand capping. ZnO was grown on the surface of PNCs through in situ organometallic reactions, and a series of Type-II PNC/ZnO heteronanocrystals (PZNCs) were prepared. Crystalline ZnO effectively passivates the surface of colloidal PNCs and significantly improves their stability under various environmental conditions. White light-emitting diodes were fabricated with green- and red-emission PZNCs that achieved no obvious decay for long-time operation in air.

High-Performance van der Waals Photodetectors Based on 2D Ruddlesden–Popper Perovskite/MoS2 Heterojunctions

Perovskites have prevailed in the field of photovoltaics over the past several years thanks to their outstanding optoelectronic properties. Compared to three-dimensional (3D) perovskites, the emerging two-dimensional (2D) Ruddlesden–Popper (RP) phase perovskites have demonstrated superior stability due to their hydrophobic organic capping ligands, which can protect the inside inorganic octahedrons against moisture. Meanwhile, RP perovskites broaden the family of 2D materials, enriching the building blocks for van der Waals heterostructures. Here, we first demonstrated a vertical heterojunction incorporating RP perovskite (C6H5C2H4NH3)2PbBr4 and MoS2. The heterojunction photodetector exhibits an extremely low dark current down to 0.1 pA, which can be attributed to the combining effect of the low carrier density in RP perovskites and the band structure of the heterojunction. The spatially resolved scanning photocurrent microscopy (SPCM) was carried out to confirm the charge transport mechanism and band alignment of the heterojunction. Moreover, the photodetector benefits from the heterojunction structure, leading to a high photoresponsivity (7.98 mA W–1). In addition, the device can be operated under a self-driven mode with a responsivity of 0.168 mA W–1. Our work proves the compatibility of RP perovskites in van der Waals devices, promising a scalable pathway to further applications.

Preparation, Characterization and Stability Studies of Gold Nanoparticles Capped by 1,2,3‐Triazole‐Based Mesoionic Carbenes

AbstractThe preparation of stable and size‐uniform AuNPs (AuNPs=gold nanoparticles) has gained extensive attention. Strongly coordinating 1,2,3‐triazole‐based mesoionic carbenes are suitable capping agents to stabilize AuNPs, but such chemistry has been rarely explored. In this work, a series of newly synthesized triazolin‐5‐ylidenes with varying wingtips have been exploited as the capping ligands. Two different synthetic approaches have been explored and compared, which employed either gold(I) complexes or gold(III) species as the precursors. The gold nanomaterials synthesized via these two routes show different characteristics in terms of particle size, surface oxidation state as well as colloidal stability. It was found that the carbene with two long aliphatic wingtips is the best capping ligand giving relatively stable and monodisperse AuNPs. In addition, one of the gold nanomaterials, NP‐IIc, has exhibited good stability in the presence of biologically relevant agents including PBS, cysteine and glutathione, which implies its potential biological applications.

Silver‐Mediated Squaric Acid Reduction as a Facile, Ambient‐temperature and Seedless Route to Tunable Bimetallic Au/Ag Nanostars and Nanosnowflakes

AbstractBimetallic Au/Ag nanoparticles were successfully synthesized using a facile and reproducible method involving rapid, room‐temperature mixing of aqueous solutions of HAuCl4 and AgNO3 in the presence of squaric acid as both the reducing agent and surface capping ligand. Variation in the initial Au : Ag molar ratio yielded a tunable anisotropic shape and affiliated surface plasmon resonance. The nanoparticles displayed excellent stability in water for at least 10 weeks and showed robust catalytic activity in the borohydride‐assisted reduction of the model substrate 4‐nitrophenol.

Growth and morphology of thermally assisted sinterable zirconia nanoparticle tribofilm

Tribofilm formation mechanisms of a novel zirconia (ZrO2) nanoparticle antiwear additive were investigated. Spherical ZrO2 nanoparticles 5 nm in diameter with organic capping ligands were dispersed in a polyalphaolefin (PAO) synthetic base oil and tested between AISI 52100 steel counterfaces in a ball-on-disk tribometer under boundary lubrication contact conditions. Film formation was studied as a function of temperature, using PAO blends to maintain constant viscosity across the different temperatures. A temperature dependence was found, with higher temperatures assisting initial tribofilm growth and maintaining the steady-state tribofilm thickness. Findings are consistent with previous reports indicating the primary mechanism of tribofilm growth for zirconium oxide is nanoparticle capture at the sliding interface followed by particle accumulation and sintering.

Capping-Ligand Density on Cu Nanoparticles Determining Multi-Carbon Product Selectivity in Electrochemical CO2 Reduction

Carbon dioxide (CO2) emission from the combustion of fossil fuel causes global warming and climate change. Much attention has been paid for recycling of CO2 gas, namely converting this greenhouse gas to high-value fuels such as multi-carbon products (ethylene, ethanol, propanol, etc.). In particular, electrochemical CO2 reduction reaction (CO2RR) is one of the promising methods operated at ambient pressure and room temperature. By using gold and silver catalysts, carbon monoxide (CO) is successfully yielded with >80% Faradaic efficiency. In contrast, it is still challenging to produce multi-carbon (i.e., C2+) products. Copper (Cu) is known as the sole catalyst to yield C2+ products by affording the suitable binding energy to the intermediate of *CO (the asterisk denotes the surface adsorption). Although various synthetic methods for the preparation of Cu nanoparticles (NPs) have been developed to increase the surface area and design of the preferred facets for the CO2 reduction, the highly sensitive Cu surface in air and from contaminants resulted in variable Faradaic efficiencies for C2+ production. In particular, the capping ligands, which coat the Cu surface to stabilize the designed nanostructures, should significantly influence the catalytic efficiency and stability. However, their effects have been little studied.Here, we show the enhanced catalytic activity and stability of Cu NPs for the C2+ yield by eliminating the capping ligands.[1] The pristine Cu NPs with ~8 nm of diameter were prepared by using a capping ligand of tetradecylphosphonate (TDP). After UV-ozone treatment, the TDP ligands were eliminated in part; The phosphorous signal was attenuated, and the Cu surface was oxidized in X-ray photoelectron spectra. In addition, the carbonyl oxygen (O=C) emerged from the damaged TDP. In contrast, the carbon substrate and the surface roughness of the Cu were insignificantly changed. These UV-ozone-treated Cu NPs showed ~50% Faradaic efficiency of the C2+ conversion (FEC2+) at –0.98 V vs. RHE, which was twice as high as that of the pristine Cu NPs (~25%). In particular, the FEC2+ gradually increased as the remaining capping ligands were removed, indicating the increased catalytic sites for 3 h CO2RR. In sharp contrast, the FEC2+ from the pristine Cu NPs was consistently low despite the partial stripping of the capping ligands, suggesting the negligible formation of the C2+ active sites. For prolonged chronoamperometry tests for 20 h, these FEC2+ values were retained for both catalysts, while the size and shape of Cu catalysts were differently changed. The UV-ozone-treated ones proceeded little agglomeration and contained many grain boundaries. In contrast, the pristine Cu NPs were transformed to the cubic particles with ~100 nm size. The distinct alternations of Cu structures are closely related to the yield of the C2+ active sites, which I will discuss in this presentation.[1] J. Mater. Chem. A, 9, 11210 (2021) Figure 1