Role Of Au Research Articles

The role of Au and Pd in photocatalytic activation of molecular oxygen: A mechanistic study

Activation of molecular oxygen plays an important role in photocatalytic selective oxidation reactions and complete degradation of organic pollutants. Noble metal cocatalysts are often employed to modulate the activation of oxygen to reach an optimum photocatalytic performance. However, the role of the metal nanoparticles (NPs) still remains unclear and deserves investigation for the design of efficient photocatalysts. Here, Au and Pd NPs are deposited on the TiO2 photocatalyst to study the promotional mechanism of O2 dissociation with the presence of glycerol under irradiation by near-ambient-pressure photoelectron spectroscopy and in-situ spectrometry approaches. While both Au and Pd NPs can dissociate O2 into activated oxygen species, a relatively strong bonds of dissociated oxygen atom is observed on Au NPs than on the Pd NPs. This results in a moderate reduction rate of O2 and eventually favors a mild oxidation reaction process for Au, and a rapid reduction rate of O2 and eventually a deep oxidation reaction process for Pd, respectively.

Rethinking African Regionalism: Assessing How Regimes Use the African Union

Abstract: This paper critically analyzes the African Union's (AU) efforts toward continental integration, highlighting the gap between its rhetoric and the actions of member states' political leaders. The paper suggests that the AU's focus on individual state sovereignty, rather than continental unity, is partly due to its self-serving role for the political elite, serving as a vessel for regime-boosting and sovereignty-enhancing purposes. The paper acknowledges some of the successes of the AU in reducing armed conflicts and military coups through its Peace and Security Council, Panels of Conflicts Resolution, and the African Standby Force for peace missions. It also recognizes the potential benefits of the African Continental Free Trade Agreement (AfCFTA), which aims to lower or eliminate cross-border tariffs on most goods, promote investment, and pave the way for a continent-wide customs union. However, the paper argues that "performative" Pan-Africanism efforts demonstrate the persistent gap between the AU's rhetoric and actions. Therefore, a close examination of the AU reveals how reigning regimes use regionalism as "opportunity structures" in political crises. The paper suggests that the AU's focus on individual state sovereignty reinforces traditional notions of sovereignty and hinders the process of continental integration. The paper contributes to the scholarship of regionalism by examining the less prominent roles of integration in Africa. It also highlights how supranational entities can be adaptive and mutative for their specific locales. Finally, the paper calls for critically examining the AU's role and potential for promoting genuine continental unity.

Effects of Au States in Thiol-Organosilica Nanoparticles on Enzyme-like Activity for X-ray Sensitizer Application: Focus on Reactive Oxygen Species Generation in Radiotherapy.

In radiotherapy, the use of Au nanoparticles (Au NPs) has been proposed to enhance cell damage by X-ray irradiation. Although the role of Au in radiotherapy is not fully understood, the catalytic activity of Au has been actively studied in the industrial field. Moreover, owing to their enzyme-like activity and high biocompatibility in vitro and in vivo, Au NPs present significant potential for biological applications. In this study, we incorporated different Au states both on the surface and embedded in thiol-organosilica (thiol-OS/Au series) to investigate the efficiency of anticancer cell activity of Au in radiotherapy. The thiol-OS/Au series comprised different Au(I)/Au(0) ratios and Au NPs, and different sizes of Au NPs were embedded in thiol-OS/Au. These thiol-OS/Au series samples were evaluated for enzyme-like activities in reactive oxygen species (ROS) generation by X-ray irradiation. Thiol-OS/Au embedded with small Au NPs (AC600/thiol-OS/Au) exhibited peroxidase (POD)-like activity under acidic conditions. This POD-like activity improved ROS generation and cytotoxicity under X-ray irradiation. Furthermore, AC600/thiol-OS/Au exhibited catalase (CAT)-like activity under basic conditions and showed no cytotoxicity toward nonirradiated cells. These results revealed the efficiency of functionalizing with small Au NPs that possess pH-controlled POD- and CAT-like activity as a radiosensitizer. We compared the suitability of using Au with different states to obtain the thiol-OS/Au series samples for application as radiosensitizers. The findings of this study will aid the design of efficacious strategies for the Au nanostructure-based radiotherapy of cancer cells.

Insights into the Effect of Metal Ratio on Cooperative Redox Enhancement Effects over Au- and Pd-Mediated Alcohol Oxidation.

The aerobic oxidation of alcohols and aldehydes over supported heterogeneous catalysts can be considered as comprising two complementary and linked processes: dehydrogenation and oxygen reduction. Significant rate enhancements can be observed when these processes are catalyzed by independent active sites, coupled by electron transport between the two catalysts. This effect, termed cooperative redox enhancement (CORE), could significantly influence how researchers approach catalyst design, but a greater understanding of the factors which influence it is required. Herein, we demonstrate that the Au/Pd ratio used in physical mixtures of monometallic catalysts and phase-separated Au and Pd bimetallic catalysts dramatically influences the degree to which CORE effects can promote alcohol oxidation. Perhaps more interestingly, the roles of Au and Pd in this coupled system are determined to be interchangeable. Preliminarily, we hypothesize that this is attributed to the relative rates of the coupled reactions and demonstrate how physical properties can influence this. This deeper understanding of the factors which influence CORE is an important development in bimetallic catalysis.

Interstitial Carbon Dopant in Palladium-Gold Alloy Boosting the Catalytic Performance in Vinyl Acetate Monomer Synthesis.

Vinyl acetate monomer (VAM), an important chemical intermediate in industry, is produced by the well-established commercial process of acetoxylation of ethylene with Pd-Au/SiO2 and a KOAc promoter. No paper has since decades defined the true effects of Au and KOAc, despite numerous attempts to clarify them. The role of subsurface carbon as a catalyst booster for enhanced catalytic performance in VAM synthesis was found by us for the first time. X-ray diffraction and X-ray absorption fine structure studies revealed that carbon atoms spontaneously doped into the Pd-Au alloy lattice while maintaining the alloy's size, metallic state, and alloy composition. Additionally, during the process, the KOAc addition dramatically raised the equilibrium carbide fraction. Because of the high carbide fraction, KOAc/Pd0.8Au0.2/SiO2 had a 5.6-fold higher formation rate (89.0% selectivity) than Pd0.8Au0.2/SiO2 (69.2% selectivity) due to high carbide fraction. Surprisingly, kinetic and theoretical analyses showed that the coupling of acetate and ethylene, which is a rate-determining step, is effectively promoted by the synergistic contributions of Au (electronic/geometric effects) and interstitial carbon (electronic effect). Additionally, the synergy inhibits ethylene dehydrogenation, which ultimately slows the formation of CO2. The contentious debates about the roles of Au and KOAc in the acetoxylation of ethylene have been resolved thanks to experimental and theoretical insights into the roles of Pd-Au formation, Au/Pd ratio, and interstitial carbon atoms. These insights also open the door for the logical design of catalysts with desirable catalytic performance.

Nano‐Au Anchored in Organic Base Group‐Grafted Silica Aerogel: A Durable and Robust Catalysts for Green Oxidative Esterification of Furfural

AbstractInorganic metal (hydro)oxide supports with appropriate basicity or acid‐base properties can promote oxidative esterification of furfural over Au‐based catalysts, however, they suffer the problems of easy inactivation induced by the leaching of the components in this water‐producing reaction and the shield of catalytic sites by product adsorption. In this work, we report efficient and stable oxidative esterification of furfural over Au nanoparticles anchored in aminopropyl‐grafted silica aerogel. The support is insoluble and possesses no strong Lewis acid sites to adsorb oxygen‐containing products or intermediates, reducing the probability of catalyst deactivation induced by adsorption. In 7 cycles of reactions, the catalyst maintained the initial activity without any treatments, the yields of alkyl furoate kept above 98 %, and no agglomeration and leaching of Au occurred. Moreover, the roles of Au, alkyl chain, −NH2 group and Au‐activated O species in reactions were clarified, and accordingly, a possible catalytic mechanism involving oxidative dehydrogenation was given.

Removal of hexavalent chromium from water by Z-scheme photocatalysis using TiO2 (rutile) nanorods loaded with Au core–Cu2O shell particles

All-solid-state Z-scheme photocatalysts, containing Cu2O, TiO2 (rutile), and Au as the electron mediator, were prepared and applied to the reduction of Cr(VI) in aqueous solutions. The Cu2O–Au–TiO2 composites were prepared by loading Au core–Cu2O shell hemisphere particles on TiO2 (rutile) nanorods using a two-step photocatalytic deposition process. Under ultraviolet–visible (UV–vis) light illumination, the Cu2O–Au–TiO2 composites exhibited higher photocatalytic Cr(VI) reduction activities than those exhibited by single TiO2 (rutile) and Cu2O. In this reaction, a precipitate containing Cr, which was considered to be Cr(OH)3, was deposited site-selectively on the Au core–Cu2O shell particles of the composites, indicating that the reduction site of the composite was Cu2O, and the reaction proceeded according to the Z-scheme. The Cu2O–Au–TiO2 composites also exhibited photocatalytic activity under visible light illumination. The oxidation state of Cu in the Cu2O–Au–TiO2 composite gradually changed from Cu(I) to Cu(II) during the photocatalytic Cr(VI) reduction. However the composite maintained its high photocatalytic performance even after oxidation. The role of Au in the Cu2O–Au–TiO2 composite was examined by comparing the properties of the Cu2O–Au–TiO2 composite with those of the Cu2O–TiO2 composite prepared via direct Cu2O deposition on TiO2.

An insight of physical and antibacterial properties of Au-doped ZnO dip coated thin films

Undoped and Au-doped ZnO thin films were dip coated on crown glass substrates by sol-gel process technique. The role of Au (1–5 at. wt.%) on structural, magnetic, morphological, dielectric, antibacterial and optical properties of the ZnO films were studied. XRD results depict that all films have a hexagonal wurtzite structure of ZnO and are a-axis oriented. The crystallite size thin films are decreased with an increase in Au doping percentage. Optical properties also confirmed that the s crystallinity degraded with the increase in Au percentage. UV–VIS–NIR optical spectra show that the increase in Au doping into ZnO lattice promotes their transparency. Surface morphology and surface roughness are modified by the Au doping concentration. Magnetic measurement exhibited room temperature ferromagnetic ordering in undoped and Au doped ZnO thin films. The enhancement in saturation magnetization with increase in Au doping is due to creation of defects in ZnO lattice by Au doping due to oxygen vacancies and structural inhomogeneity which leads to development of bound magnetic polarons. Variation in AC conductivity with change in Au dopant percentage is studied using Jonscher's power law which is linked with barrier-hopping mechanism. Au doped ZnO is effective against gram positive and gram-negative bacteria. These have antimicrobial applications in biomedicine and environmental shield. Au doped ZnO thin films are beneficial in spin LEDs and switchable diodes. The Au doped ZnO photocatalyst can efficiently degrade methylene blue dye; hence, it can be used for the treatment of wastewater contamination.

The Direct Synthesis of Hydrogen Peroxide over AuPd Nanoparticles: An Investigation into Metal Loading

The direct synthesis of H2O2 from molecular H2 and O2 over AuPd catalysts, supported on TiO2 and prepared via an excess chloride co-impregnation procedure is investigated. The role of Au:Pd ratio on the catalytic activity towards H2O2 formation and its subsequent degradation is evaluated under conditions that have previously been found to be optimal for the formation of H2O2. The combination of relatively small nanoparticles, of mixed Pd-oxidation state is shown to correlate with enhanced catalytic performance. Subsequently, a detailed study of catalytic activity towards H2O2 synthesis as a function of AuPd loading was conducted, with a direct correlation between catalytic activity and metal loading observed.Graphic

Strange hadron production in a quark combination model in Au+Au collisions at energies available at the BNL Relativistic Heavy Ion Collider

We apply a quark combination model to study yield densities and transverse momentum ($p_{T}$) spectra of strange (anti-)hadrons at mid-rapidity in central Au+Au collisions at $\sqrt{s_{NN}}=$ 7.7, 11.5, 19.6, 27, 39 and 200 GeV. We show that experimental data for $p_{T}$ spectra of (anti-)hadrons in these collisions can be systematically described by the equal velocity combination of constituent quarks and antiquarks at hadronization. We obtain $p_{T}$ spectra of quarks and antiquarks at hadronization and study their collision energy dependence. We also reproduce the yield densities of hadrons and anti-hadrons. In particular, we demonstrate that yield ratios of anti-hadrons to hadrons $K^{-}/K^{+}$, $\bar{p}/p$, $\bar{\Lambda}/\Lambda$, $\bar{\Xi}^{+}/\Xi^{-}$ and $\bar{\Omega}^{+}/\Omega^{-}$ simply correlate with each other and their experimental data except $\bar{\Omega}^{+}/\Omega^{-}$ at $\sqrt{s_{NN}}=$ 7.7 GeV are systematically described by the model. These results suggest that the equal velocity combination mechanism for quarks and antiquarks at hadronization plays an important role in Au+Au collisions at low RHIC energies ($\sqrt{s_{NN}}\geq$ 11.5 GeV).

The Origin of Au/Ce1-xZrxO2 Catalyst’s Active Sites in Low-Temperature CO Oxidation

Gold catalysts have found applications in many reactions of both industrial and environmental importance. Great interest has been paid to the development of new processes that reduce energy consumption and minimize pollution. Among these reactions, the catalytic oxidation of carbon monoxide (CO) is an important one, considering that a high concentration of CO in the atmosphere creates serious health and environmental problems. This paper examines the most important achievements and conclusions arising from the own authorship contributions concerning (2 wt. % Au)/Ce1−xZrxO2 catalyst’s active sites in low-temperature CO oxidation. The main findings of the present review are: (1) The effect of preparing conditions on Au crystallite size, highlighting some of the fundamental underpinnings of gold catalysis: the Au surface composition and the poisoning effect of residual chloride on the catalytic activity of (2 wt. % Au)/Ce1−xZrxO2 catalysts in CO oxidation; (2) The identification of ion clusters related to gold and their effect on catalyst’ surface composition; (3) The importance of physicochemical properties of oxide support (e.g., its particle size, oxygen mobility at low temperature and redox properties) in the creation of catalytic performance of Au catalysts; (4) The importance of oxygen vacancies, on the support surface, as the centers for oxygen molecule activation in CO reaction; (5) The role of moisture (200–1000 ppm) in the generation of enhanced CO conversion; (6) The Au-assisted Mars-van Krevelen (MvK) adsorption–reaction model was pertinent to describe CO oxidation mechanism. The principal role of Au in CO oxidation over (2 wt. % Au)/Ce1−xZrxO2 catalysts was related to the promotion in the transformation process of reversibly adsorbed or inactive surface oxygen into irreversibly adsorbed active species; (7) Combination of metallic gold (Au0) and Au-OH species was proposed as active sites for CO adsorption. These findings can help in the optimization of Au-containing catalysts.

Effective medium theory to the description of plasmonic resonances: Role of Au and Ti nanoparticles embedded in MoO3 thin films

The growing interest in functional transition metal oxides for efficient energy consumption or in the bio-sensing process; indicates that is necessary to develop a new theoretical method that describes experiments. This article presents a new theoretical methodology to characterize molybdenum trioxide (MoO3) thin films doped with resonant gold – nanoparticles (Au – NPs) and non-resonant titanium – nanoparticles (Ti – NPs). The modulation of surface plasmon resonance (SPR) and the implications in the MoO3 transmittance spectrum is described by applying an effective medium theory. The transmittance modulation was modified by variating three parameters, the radius of the NPs, the concentration of the NPs as well as the variation of the MoO3 thin films thickness. It was found that the nanoparticles concentration is the most important parameter in the transmittance modulation. Additionally, the orthorhombic and monoclinic structure of MoO3 was studied, from which it was obtained that the monoclinic structure of the MoO3 doped with Au – NPs favors the reduction in the transmittance values in the visible region which is associated with the increase of the SPR signal. Similar analyses are performed for non-resonant nanoparticles such as Ti, where it was found that optical modulation is not as marked as the case of gold nanoparticles.

Highly Efficient Adsorption of Au(III) from Water by a Novel Metal–Organic Framework Constructed with Sulfur-Containing Ligands and Zn(II)

Recovery of precious metal ions from wastewater can bring huge economic benefits and alleviate current supply shortage in industries. Here, a novel metal–organic framework (2,5-TP) constructed with sulfur-containing ligands and Zn(II) was synthesized as a highly efficient adsorbent to adsorb Au(III) from water for the first time. Compared with that of the reported adsorbents, 2,5-TP exhibits excellent Au(III) adsorption performance with the maximum adsorption capacity of 1253.5 mg·g–1 and an adsorption ratio of 97%. Significantly, 2,5-TP has excellent selectivity toward Au(III) and remarkable recycle performance. The adsorption kinetics for Au(III) adsorption can be described well by the pseudo-second-order kinetics and the adsorption isotherm data accord well with the Sips model, indicating that the adsorption of Au(III) onto 2,5-TP is a heterogeneous chemisorption process. The formation of Au–S and Zn–O–Au bonds suggests an important role in Au(III) adsorption. With the facile synthesis, high adsorption...

Revealing the Role of Gold in the Growth of Two-Dimensional Molybdenum Disulfide by Surface Alloy Formation.

The formation of Mo/Au surface alloy during Au-assisted chemical vapor deposition (CVD) of MoS2 is confirmed by a series of control experiments. A metal-organic chemical vapor deposition (MOCVD) system is adapted to conduct two-dimensional MoS2 growth in a controlled environment. Sequential injection of Mo and S precursors, which does not yield any MoS2 on SiO2 /Si, grows atomically thin MoS2 on Au, indicating the formation of an alloy phase. Transmission electron microscopy of a cross-section of the specimen confirms the confinement of the alloy phase near the surface only. These results show that the reaction intermediate is the surface alloy, and that the role of Au in the Au-assisted CVD is the formation of an atomically thin reservoir of Mo near the surface. This mechanism is clearly distinguished from that of MOCVD, which does not involve the formation of any alloy phases.

Kinetic Map for Destabilization of Pt-Skin Au Nanoparticles via Atomic Scale Rearrangements

A commonly used strategy to enhance the mass activity of Pt-based catalysts involves the synthesis of Au nanoparticles (NPs) with a monolayer-thick Pt-skin layer. The synergistic effect of Au and Pt results in a higher catalytic activity and better Pt utilization. However, the stability of the Pt-skin layer is questionable as our recent equilibrium Monte Carlo simulations predict that eventually the surface Pt is replaced by Au. The role of Au during destabilization of Pt-skin in vacuum and solution is investigated with the help of molecular dynamics. Different starting Au–Pt arrangements are studied mimicking various NP synthesis approaches. Beyond a critical number of atoms in a Pt cluster, the ideal Pt monolayer rapidly transforms to a three-dimensional (3D) Pt cluster. This is supported by our model predicting transition from the Pt monolayer to Volmer–Weber growth in the Au–Pt system. At room temperature, Pt atoms move into the subsurface layer at second timescales mainly via the exchange mechanism i...

New insights on hydrogen evolution at Au single crystal electrodes

Summary The understanding of fundamental relationships between the structure of an electrode and its activity for a given reaction is crucial for catalyst development in electrocatalysis. The hydrogen evolution reaction (HER) on Au single crystal electrodes belongs to the class of structure-sensitive processes. HER can be used to study dynamic processes of the electrode surface. It is shown that kinetics of surface reconstruction is significantly dependent on the electrode potential. The role of Au in binary electrocatalysts for HER is discussed.

Role of Au(NPs) in the enhanced response of Au(NPs)-decorated MWCNT electrochemical biosensor.

BackgroundThe combination of Au-metallic-NPs and CNTs are a new class of hybrid nanomaterials for the development of electrochemical biosensor. Concentration of Au(nanoparticles [NPs]) in the electrochemical biosensor is crucial for the efficient charge transfer between the Au-NPs-MWCNTs modified electrode and electrolytic solution.MethodsIn this work, the charge transfer kinetics in the glassy carbon electrode (GCE) modified with Au(NPs)–multiwalled carbon nanotube (MWCNT) nanohybrid with varied concentrations of Au(NPs) in the range 40–100 nM was studied using electrochemical impedance spectroscopy (EIS). Field emission scanning electron microscopy and transmission electron microscopy confirmed the attachment of Au(NPs) on the surface of MWCNTs.ResultsThe cyclic voltammetry and EIS results showed that the charge transfer mechanism was diffusion controlled and the rate of charge transfer was dependent on the concentration of Au(NPs) in the nanohybrid. The formation of spherical diffusion zone, which was dependent on the concentration of Au(NPs) in nanohybrids, was attributed to result in 3 times the increase in the charge transfer rate ks, 5 times increase in mass transfer, and 5% (9%) increase in Ipa (Ipc) observed in cyclic voltammetry in 80 nM Au(NP) nanohybrid-modified GCE from MWCNT-modified GCE. The work was extended to probe the effect of charge transfer rates at various concentrations of Au(NPs) in the nanohybrid-modified electrodes in the presence of Escherichia coli. The cyclic voltammetry results clearly showed the best results for 80 nM Au(NPs) in nanohybrid electrode.ConclusionThe present study suggested that the formation of spherical diffusion zone in nanohybrid-modified electrodes is critical for the enhanced electrochemical biosensing applications.

A high-performance electrochemical sensor for biologically meaningful l-cysteine based on a new nanostructured l-cysteine electrocatalyst

As a new class of l-cysteine electrocatalyst explored in this study, Au/CeO2 composite nanofibers (CNFs) were employed to modify the screen printed carbon electrode (SPCE) to fabricate a novel l-cysteine (CySH) electrochemical sensor with high performance. Its electrochemical behavior and the roles of Au and CeO2 in the composite toward electro-oxidation of CySH were elucidated and demonstrated using cyclic voltammetry and amperometry techniques for the first time through the comparison with pure CeO2 NFs. More specifically, the Au/CeO2 CNFs modified SPCE possessed greatly enhanced electrocatalytic activity toward CySH oxidation. An ultra high sensitivity of 321 μA mM−1cm−2 was obtained, which is almost 2.7 times higher than that of pure CeO2 NFs, revealing that the presence of Au imposed an important influence on the electrocatalytic activity toward CySH. The detailed reasons on such high performance were also discussed. In addition, the as-prepared sensor showed a low detection limit of 10 nM (signal to noise ratio of 3), a wide linear range up to 200 μM for the determination of CySH, an outstanding reproducibility and good long-term stability, as well as an excellent selectivity against common interferents such as tryptophan, tyrosine, methionine, ascorbic acid and uric acid. All these features indicate that the Au/CeO2 composite nanofiber is a promising candidate as a new class of l-cysteine electrocatalyst in the development of highly sensitive and selective CySH electrochemical sensor.

Fabrication of sandwich-structured g-C3N4/Au/BiOCl Z-scheme photocatalyst with enhanced photocatalytic performance under visible light irradiation

A novel sandwich-structured g-C3N4/Au/BiOCl Z-scheme heterojunction with enhanced visible-light-driven photocatalytic activity was successfully fabricated using the reactable ionic liquid (1-methyl-3-[3’-(trimethoxysilyl) propyl] imidazolium chloride) as the template by a facile photoreduction followed by in situ deposition. The samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, scanning electron microscope and ultraviolet–visible diffuse reflectance spectroscopy. The role of Au in this system was discussed during the degradation of rhodamine B and tetracycline and photocatalytic hydrogen evolution under visible light irradiation. The influence of BiOCl dosage on the photocatalytic activity was also systematically investigated. The result found that the photocatalytic activity was improved using the as-fabricated CN/Au/BiOCl Z-scheme heterojunction than g-C3N4 or BiOCl. Besides, the fast separation rate of photogenerated electron–hole pairs and the improved light absorption in visible ranges of CN/Au/BiOCl samples might be related to the fact that the construction of Z-scheme could improve the optical and conductive properties and enhance the final photocatalytic property. From the free radicals trapping experiments, it was found that the photogenerated holes of BiOCl were the predominant active species in the photocatalytic process.

Role of Au(I) Intermediates in the Electrochemical Formation of Highly Anisotropic Gold Nanostructures with Near-IR SERS Applications

In the presence of certain stabilizing ligands, such as pyridine derivatives, the reduction of Au(III) ions has been speculated to generate Au(I) intermediates that may play a key role in nanoparticle growth. Herein, the electrochemical behavior of Au(III) in the presence of 4-methoxypyridine, Py, is reported in aqueous electrolytes. Voltammetric analysis reveals that a spontaneously formed Au(III)–Py complex undergoes a two-step reduction process. The first reduction involves the transfer of two electrons and produces a Au(I) species. A more cathodic one-electron transfer results in electrodeposited gold. Sustained generation of the Au(I)–Py intermediate species produced from the first reduction step leads to disproportionation and the formation of aggregated nanoparticle meshes that loosely adhere to the ITO electrode. Conversely, application of more negative potentials leads to the formation of highly anisotropic nanodaggers from the electrodeposition of the Au(I) species. The shape-directing propertie...