Small Au Research Articles

Laser Ablation-Assisted Synthesis of Plasmonic Si@Au Core-Satellite Nanocomposites for Biomedical Applications.

Owing to strong plasmonic absorption and excellent biocompatibility, gold nanostructures are among best candidates for photoacoustic bioimaging and photothermal therapy, but such applications require ultrapure Au-based nanoformulations of complex geometry (core-shells, nanorods) in order to shift the absorption band toward the region of relative tissue transparency (650–1000 nm). Here, we present a methodology for the fabrication of Si@Au core-satellite nanostructures, comprising of a Si core covered with small Au nanoparticles (NP), based on laser ablative synthesis of Si and Au NPs in water/ethanol solutions, followed by a chemical modification of the Si NPs by 3-aminopropyltrimethoxysilane (APTMS) and their subsequent decoration by the Au NPs. We show that the formed core-satellites have a red-shifted plasmonic absorption feature compared to that of pure Au NPs (520 nm), with the position of the peak depending on APTMS amount, water−ethanol solvent percentage and Si−Au volume ratio. As an example, even relatively small 40-nm core-satellites (34 nm Si core + 4 nm Au shell) provided a much red shifted peak centered around 610 nm and having a large tail over 700 nm. The generation of the plasmonic peak is confirmed by modeling of Si@Au core-shells of relevant parameters via Mie theory. Being relatively small and exempt of any toxic impurity due to ultraclean laser synthesis, the Si@Au core-satellites promise a major advancement of imaging and phototherapy modalities based on plasmonic properties of nanomaterials.

Synergistic effect between CeO2 nanowires and gold NPs over the activity and selectivity in the oxidation of thioanisole

Gold nanoparticles incorporated on ceria nanowires have been employed as efficient nanocatalysts for the selective oxidation of thioanisole. The control of both physical and chemical parameters as well as metal–support interactions are important factors that determine their performances. Considering their one-dimensional morphology with large surface area, thin diameters, high concentration of oxygen vacancies, and small Au NPs uniformly on the entire CeO2 surface with a high fraction of oxidized gold species, these characteristics make them favorable nanocatalysts for oxidation transformations. The CeO2-Au nanowires displayed improved performances towards the oxidation of thioanisole when compared to the pure CeO2 nanowires and commercial CeO2-Au catalysts. The CeO2-Au nanowires catalyzed the selective synthesis of methyl phenyl sulfoxide with up to 100 % of selectivity and high conversion. The impact of solvent and temperature during the catalytic reaction was also experimentally and theoretically investigated by DFT calculations, indicating a key role in the observed activities.

Electrochemical Stability and Degradation Mechanisms of Commercial Carbon-Supported Gold Nanoparticles in Acidic Media.

Electrochemical stability of a commercial Au/C catalyst in an acidic electrolyte has been investigated by an accelerated stress test (AST), which consisted of 10,000 voltammetric scans (1 V/s) in the potential range between 0.58 and 1.41 VRHE. Loss of Au electrochemical surface area (ESA) during the AST pointed out to the degradation of Au/C. Coupling of an electrochemical flow cell with ICP-MS showed that only a minor amount of gold is dissolved despite the substantial loss of gold ESA during the AST (∼35% of initial value remains at the end of the AST). According to the electrochemical mass spectrometry experiments, carbon corrosion occurs during the AST but to a minor extent. By using identical location scanning electron microscopy and identical location transmission electron microscopy, it was possible to discern that the dissolution of small Au particles (<5 nm) within the polydisperse Au/C sample is the main degradation mechanism. The mass of such particles gives only a minor contribution to the overall Au mass of the polydisperse sample while giving a major contribution to the overall ESA, which explains a significant loss of ESA and minor loss of mass during the AST. The addition of low amounts of chloride anions (10–4 M) substantially promoted the degradation of gold nanoparticles. At an even higher concentration of chlorides (10–2 M), the dissolution of gold was rather effective, which is useful from the recycling point of view when rapid leaching of gold is desirable.

Stellate porous silica based surface-enhanced Raman scattering system for traceable gene delivery

Numerous nanocarriers have been currently developed for intracellular delivery. The potential cytotoxicity of these very small inorganic nanocarriers has raised great consideration. Thus, it becomes of utmost importance to conduct the intracellular trace of nanocarriers. Among many analytical techniques, surface enhanced Raman scattering (SERS) method is one of the current state-of-the-art techniques for cell visualization and trace. In this work, a novel stellate porous silica based gene delivery system has been designed for SERS trace purpose. A stellate porous silica nanoparticle modified with many small Au nanoparticles is designed to replace common metallic SERS tags. The results show that the designed system not only could deliver siRNA into cells for therapy, but also could realize SERS trace with high sensitivity and non-invasive features. The constructed delivery system has considerable potential to trace the dynamic gene delivery in living cells.

Ligand effects in the stabilization of gold nanoparticles anchored on the surface of graphene: Implications in catalysis

Gold nanoparticles (Au NPs) functionalized with N-heterocyclic carbene (NHC) ligands immobilized onto graphene are obtained via spontaneous decomposition of well-defined gold-NHC complexes by reduced graphene oxide (rGO) without reducing agents. NHC ligands are responsible for the formation of air-stable, crystalline and small (3.0–4-0 nm) Au NPs homogeneously distributed on the surface of graphene. The catalytic properties of three Au NPs functionalized with different ligands were tested in two benchmark reactions (hydration of alkynes and intramolecular hydroamination of alkynes). The results reveal a pronounced ligand effect on the stability of Au NPs on graphene, by acting as a bridge between them. The Au NPs functionalized with a NHC ligand lacking a polyaromatic group or having a naphthyl tag displayed limited stability and fast deactivation in the first run. On the contrary, the Au NPs functionalized with a NHC ligand containing a pyrenyl handle showed superior catalytic activity and can be recycled at least ten times. The particle size of the Au NPs is preserved after the recycling process indicating a high stability. These results illustrate the use of purposely designed ligands having affinity for both Au NPs and graphene to increase the stability of the hybrid catalyst.

Synthesis of small Ni-core-Au-shell catalytic nanoparticles on TiO2 by galvanic replacement reaction.

We report the first preparation of small gold–nickel (AuNi) bimetallic nanoparticles (<5 nm) supported on titania by the method of galvanic replacement reaction (GRR), evidenced by the replacement of Ni atoms by Au atoms according to the stoichiometry of the reaction. We showed that this preparation method allowed not only the control of the gold and nickel contents in the samples, but also the formation of small bimetallic nanoparticles with strained core–shell structures, as revealed by aberration-corrected scanning transmission electron microscopy in combination with energy-dispersive X-ray spectroscopy mapping. The catalytic characterization by the probe reaction of semi-hydrogenation of butadiene showed that the resulting nickel-based nanocatalysts containing a small amount of gold exhibited higher selectivity to butenes than pure nickel catalysts and a high level of activity, closer to that of pure nickel catalysts than to that of pure gold catalysts. These improved catalytic performances could not be explained by a mere structural model of simple core–shell structure of the nanoparticles. Instead, they could come from the incorporation of Ni within the gold surface and/or from surface lattice relaxation and subsurface misfit defects.

A facile wet-chemistry approach to engineer an Au-based SERS substrate and enhance sensitivity down to ppb-level detection.

A two-dimensional flexible surface-enhanced Raman scattering (SERS) filter substrate provides an alternative strategy for the highly sensitive portable detection of various toxic molecules and biomaterials. Herein, we developed a solid-liquid interfacial reduction reaction to post-engineer a solid Au nanostructure surface on filter paper to improve the SERS effect. Among four reductants (ascorbic acid, l-dopamine, hydroquinone (HQ), and formaldehyde), HQ possessed a larger oxidation overpotential and facilitated homogeneous growth, forming small Au branch-structure nanoparticles from HAuCl4 solution. Due to the surface effect by exposing abundant -OH groups and intrinsic aromatic rings from TNA/HQ on nano-gold, the SERS effect on positively charged analytes near the plasmonic Au surface was enhanced, while forming a protective layer against severe water interruption. The resulting SERS substrate with branched nano-gold provided several SERS-enhanced sites, increased the enhancement by more than 6 times compared to original SERS sensing, and displayed a 1.4-7.4 × 105 analytical enhancement factor, which leads to a limit of detection down to several ppb. Less than 6% of deviation in the SERS intensity at different sensing sites was observed. We successfully improved the primary SERS substrate using a high overpotential reductant. Owing to its soft and flexible properties, the paper-based SERS substrate can be used conveniently in different sizes, pasting on curved materials, detecting additives in fish, and preventing the coffee-ring effect, showing high practicality and potential commercial value in the future.

Gold-spiked coating of silver particles through cold nanowelding.

Herein, we present a method to obtain particles composed of a segregated alloy of silver coated with gold. These particles are achieved through the controlled Ostwald ripening of small gold nanoparticles (NPs) on the surfaces of larger silver particles. The prepared segregated nanoalloyed colloids benefit from the advantages of gold and silver with none of their drawbacks. These platforms provide optical efficiencies which are superior to those of silver with the chemical resistance and biocompatibility of gold.

Synthesis and Characterization of Pollen Extract Mediated Gold Nanostructures

There is an increasing demand in the synthesis of shape and size-controlled gold nanostructures (Au NSs) with greener methods. Therefore, we aimed to synthesize differently shaped and sized Au NSs using a greener technique under ambient conditions. In this study, we utilized pollen extracts of Corylus avellana, Juniperus oxycedrus and Pinus nigra species (collected from Kastamonu region of Turkey) for the synthesis. The extraction was performed in water in order to recover water soluble content from the pollen grains. The extracts were used to stabilize, and shape/size direct the HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) buffer synthesized Au NSs. UV-vis, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) characterizations proved synthesis of spherical, anisotropic and large Au NSs with this benign approach. The obtained Au NSs were possible to separate small and large Au NSs through centrifugation. Chemistry of pollen extracts played key role on morphology and stability of the Au NSs. The findings, for the first time, is revealing the synthesis of large Au nanorod bundles (&gt;300 nm) along with hexagonal and spherical Au NSs under ambient conditions using pollen grain extracts, whose maturation took 24h.

Supported nanoparticle synthesis with Au bis-Ethylenediamine: The mechanism of adsorption onto oxides and carbons

Gold bis-ethylenediamine ([Au(en)2]3+ or AuED) is an effective precursor for the preparation of small Au nanoparticles on common catalyst supports. By studying the adsorption of AuED over a wide variety of supports with surveys of uptake versus time and pH, including XAS studies of solution and adsorbed species, we have demonstrated that an electrostatic mechanism accounts for the data much better than the previously postulated cation exchange mechanism. In the electrostatic mechanism 1) uptake-pH curves are volcano-shaped and are higher in amplitude and broader in pH the lower the PZC of the support, 2) AuED complexes retain at least one hydration sheath with diameter 13.3 Å (0.72 complex/nm2) and adsorb as outer sphere complexes, 3) the monolayer limit in aqueous solutions basified with NaOH is not determined by cation exchange stoichiometry but is a steric limit of close-packed, hydrated complexes. They adsorb at a much lower surface density than that of the surface hydroxyl groups and never electrically saturate the surface. 4) The change in AuED speciation at high pH is consistent with a change in the coulombic attraction of a 3+ versus a 2+ complex.Over carbon supports, adsorption is predominantly electrostatic, but an additional parallel mechanism is apparent in proportion to the graphitic nature of the support.Synthesized Au nanoparticles over the oxide and carbon materials was characterized by high sensitivity powder XRD, STEM imaging, and TPR. The resultant nanoparticles were generally smaller than other synthesis methods reported in the literature for silica, titania, alumina, and carbon. The loading limit of electrostatic adsorption is a surface density of about 1 μmol/m2. At loadings less than or equal to this, electrostatic adsorption provides a simple method with which to synthesize well dispersed Au nanoparticles.

Self‐Limiting Assembly of Au Nanoparticles Induced by Localized Dynamic Metal‐Phenolic Interactions

Dynamic nanoparticle assembly represents an important platform for the creation of functional materials with stimuli‐responsive properties. In this work, we show that small Au nanoparticles (ca. 5 nm) with mixed surface ligands (citrates and tannic acid) may be assembled into quasi‐sphere‐like superstructures (ca. 50 nm) induced by the presence of ferric ions. The spontaneous self‐limiting assembly is enabled by the localized metal‐phenolic interactions as a result of the possible phase separation of citrates and tannic acid on the surface of Au nanoparticles, restricting the growth of ionic cross‐linking network. The disassembly may be further achieved by adding ethylenediaminetetraacetic acid as a stronger chelation ligand for ferric ions, allowing the reversible assembly and disassembly of Au nanoparticles. Our results provide new insights into the design of dynamic plasmonic assemblies by manipulating the nature of surface ligands.

Synergistic integration of Au nanoparticles, Co-MOF and MWCNT as biosensors for sensitive detection of low-concentration nitrite

Nitrite has been widely existed in food and natural environment systems. To protect the environmental safety and human health, non-enzymatic nitrite sensor with reasonable linear response range, low detection limit (LOD) and excellent storage stability are highly desirable. Herein, we designed a hierarchical structure including the multiwalled carbon nanotube (MWCNT) as substrates, Co-based metal-organic framework (Co-MOF) and high-dispersed small Au nanoparticles (AuNPs) (denoted as AuNPs/Co-MOF/MWCNT). Small Co-MOF nanoplates were firstly grown on the surface of MWCNT, and then provides abundant adsorption sites for catching Au ions. The Co-MOF plays a crucial role in controlling the growth and dispersion of AuNPs, and limits particle growth during the reduction process. Combining MWCNT with Co-MOF can significantly improve the electron transport capability of Co-MOF. On the other hand, small and uniform AuNPs distributed on Co-MOF can reduce the operating voltage and significantly enhance their catalytic activity for nitrite oxidation. Owing to the intriguing synergy between the components, the obtained nitrite sensor device exhibits a broad linear response range from 1 to 1000 µM and a LOD of 0.4 µM (S/N = 3) with a fast response balance (the response time ≈ 3.5 s) at a voltage of 0.72 V. Moreover, this sensor remains 94.5% of their initial response after 20 days of storage at room temperature in air. These results suggested that the AuNPs/Co-MOF/MWCNT nanocomposite has a good application prospect in the amperometric determination of nitrite.

More reactive oxygen species generation facilitated by highly dispersed bimodal gold nanoparticle on the surface of Bi2WO6 for enhanced photocatalytic degradation of ofloxacin in water

An essential strategy to eliminate emerging contamination in water is to initiate more reactive oxygen species (ROS) in the catalytic systems. 0.14 wt.% Au loaded Bi2WO6 (Bi2WO6/Au-400 °C) was fabricated after 400 °C annealing with the assistance of glutathione for Au atom anchoring and stabilization on Bi2WO6 surface. Bimodal Au size distribution of highly dispersed small size clusters (0.5 ± 0.1 nm) and large size nanoparticles (6.3 ± 1.0 nm) simultaneously existed on Bi2WO6 nanosheets in Bi2WO6/Au-400 °C, which were verified through high resolution transmission electron microscopy (HR-TEM). 95% of ofloxacin (OFX) was degraded over Bi2WO6/Au-400 °C in 180 min under visible light irradiation with a reaction constant of 24.5 × 10−3 min−1, which showed 3.0 and 2.5-fold enhancement compared with bare Bi2WO6 and unimodal Bi2WO6/Au-500 °C (annealed at 500 °C, Au NPs (8.6 ± 1.0 nm)), respectively. The enhanced catalytic activity originated from the additional ROS production that initiated by photo-induced electron transported from small Au clusters to large Au NPs through the conduction band of Bi2WO6. Moreover, it still maintained a good stability after five cycling performance and the total cost of 10 g Bi2WO6/Au-400 °C was estimated to be 6.78 $. Lower-content of bimodal Au NPs decorated Bi2WO6 catalyst possesses high efficiency to degrade pollutant and lower cost, which provides a promising alternative in practical environmental remediation by photocatalysis.

Hydrogen production via water-gas shift reaction over gold supported on Ni-based layered double hydroxides

Co-precipitated NiAl and NiMgAl layered double hydroxides (LDHs) were prepared at M2+/Al3+ molar ratio of 2.5/1 and subsequently promoted with gold targeting to be studied as catalysts and supports of gold particles in the hydrogen production via water-gas shift (WGS) reaction. Powder X-ray diffraction and N2 physisorption before and after WGS tests were applied to investigate the impacts of Mg and Au on the structure and catalytic behavior of the systems. Partial replacement of Ni by Mg resulted in moderate activity of NiMgAl and Au/NiMgAl catalysts than NiAl analogues due to: (i) smaller Ni amount that could not supply sufficient number catalytically active sites; (ii) higher thermal stability leading to the creation of the active Ni species at higher temperatures, and (iii) partial regeneration of the layered structure with the assistance of small Au particles, Mg, and the reaction medium as well. Favorable role of gold on Au/NiAl WGS activity was elucidated.

In Situ Anchoring Ultra Small Au Nanoparticles by Conformal Coating of Carbon Layer within the Micro-Environments of Mesoporous Silica for Highly Efficient Catalytic Reduction of 4-nitrophenol

For the noble-metal based catalysts, the metal dispersion and sinter resistance of the metal nanoparticles (NPs) are the most vital factors for their application in series catalytic reactions. However, in the most noble-metal based catalysts, the weak interaction between metal NPs and support would be negative for these factors, and the poor catalytic performance would be obtained relatively. Committed to overcome these, in this work, the catalyst of Au@C/AMS would be designed and fabricated by the hydrothermal and calcinations process, in which the ultra small Au NPs are formed and stabilized in situ by the conformal coating of carbon layer in the micro-environment of mesoporous silica. The results demonstrate that the carbon layer would be directly formed in the mesoporous channels by calcinations in nitrogen atmosphere, and the ultra small Au NPs would be in situ anchored in the carbon layer. The average particle size of Au in Au@C/AMS is as small as 1.8 nm from TEM results, which is much smaller than those in the sample of Au/AMS without the protection of carbon layer. Besides, compared with the samples that the Au NPs are deposited on the outer and inner surface of mesoporous silica, a strong interaction would be built between Au NPs and support in the target Au@C/AMS sample. As expected, the catalyst of Au@C/AMS displays superior catalytic activity and stability in the liquid-phase reduction of 4-nitrophenol. The construction of this special architecture for Au-based catalysts could provide new sights for the design and fabrication of noble metal-based mesoporous materials with desirable catalytic activity and stability. In this work, the catalyst of Au@C/AMS would be designed and fabricated by the hydrothermal and calcinations process, in which the ultra small Au NPs are formed and stabilized in situ by the conformal coating of carbon layer in the micro-environment of mesoporous silica. Compared with the samples that the Au NPs are deposited on the outer and inner surface of mesoporous silica, a strong interaction would be built between Au NPs and support in the target Au@C/AMS sample. As expected, the catalyst of Au@C/AMS displays superior catalytic activity and stability in the liquid-phase reduction of 4-nitrophenol. The construction of this special architecture for Au-based catalysts could provide new sights for the design and fabrication of noble metal-based mesoporous materials with desirable catalytic activity and stability.

Nano-Au-modified TiO2 grown on dendritic porous silica particles for enhanced CO2 photoreduction

Titania dioxide (TiO2) is widely studied for photocatalytic CO2 reduction among various semiconductor photocatalysts due to simple preparation, low cost, high stability and suitable band gap. However, the CO2 conversion efficiency of most TiO2-based photocatalysts is still relatively low, especially in the visible light region owing to their weak light absorption capacity. In this work, we employed dendritic porous silica nanospheres (DPSNs) with center-radial large pores as a carrier to grow TiO2 nanoparticles (NPs) on the surface of center-radial pores and then load small Au NPs on the well-dispersed TiO2 NPs. Eventually, a series of [email protected]2@Au nanocomposites with different sizes of Au NPs were successfully constructed by controlling the calcination time. Due to the introduction of Au with the Local Surface Plasmaon Resonance (LSPR) effect, [email protected]2@Au with appropriate size (3–5 nm) of Au NPs exhibited superior CH4 production rate of 34.25 μmol·g-TiO2@Au−1·h−1, medium CO production rate of 15.27 μmol·g-TiO2@Au−1·h−1 and high cycle stability under simulated sunlight irradiation with 300 W Xe lamp. This work may provide some inspiration for the design of the supported photocatalysts.

A novel multi-stimuli-responsive theranostic nanomedicine based on Fe3O4@Au nanoparticles against cancer

A novel multi-stimuli-responsive theranostic nanomedicine was designed and fabricated by the conjugation of a thiol end-capped poly(N-isopropylacrylamide-block-acrylic acid) (HS-PNIPAAm-b-PAA) onto Fe3O4@Au nanoparticles (NPs) followed by physical loading of doxorubicin hydrochloride (Dox) as a general anticancer drug. For this purpose, Fe3O4@Au NPs were fabricated through small Au nanolayer grown on larger magnetic NPs. A HS-PNIPAAm-b-PAA was synthesized through an atom transfer radical polymerization (ATRP) approach, and then conjugated with as-synthesized Fe3O4@Au NPs by Au-S bonding. The Dox loading capacity of the synthesized Fe3O4@Au/Polymer theranostic NPs was calculated to be 81%. The theranostic nanomedicine exhibited excellent in vitro drug release behavior under pH and thermal stimuli. The anticancer activity evaluation using MTT assay (against MCF7 cells) revealed that the fabricated Fe3O4@Au/Polymer has high potential as theranostic nanomedicine for cancer therapy of solid tumors. This nanosystem can also applied in photothermal therapy, hyperthermia therapy, and their combination with chemotherapy due to presence of gold and Fe3O4 nanomaterials in its structure.

Semihollow Core-Shell Nanoparticles with Porous SiO2 Shells Encapsulating Elemental Sulfur for Lithium-Sulfur Batteries.

Lithium-sulfur batteries have shown great promise as next-generation high energy density power sources, but their commercial applications are hindered by short battery cycle life arising from the dissolution and shuttling of polysulfides. To address this shortcoming, we prepared two types of semihollow core-shell nanoparticles in which (1) elemental sulfur is encapsulated within a porous silica shell (S@SiO2) and (2) elemental sulfur is encapsulated within a porous silica shell where the inner surface of the shell is decorated with small Au nanoparticles (S@Au@SiO2). These core-shell nanoparticles, both ∼300 nm in diameter, were generated from analogous zinc sulfide-based core-shell nanoparticles (ZnS@SiO2 and ZnS@Au@SiO2, respectively) by converting the ZnS cores to elemental sulfur upon treatment with Fe(NO3)3. With a high surface area and strong host-polysulfide interaction, the SiO2 shells effectively trap the polysulfides; moreover, the internal void space of these nanostructures accommodates the volume expansion of the sulfur core upon lithiation. By decorating ∼5-7 nm Au nanoparticles evenly on the inner surface of the porous SiO2 shells (i.e., S@Au@SiO2), electron transport is enhanced, with consequently enhanced sulfur conversion kinetics at high current rates. Studies of battery performance showed that the S@SiO2 cathode can deliver an initial capacity of 1153 mA h g-1 under 0.2 C and retain 816 mA h g-1 after 100 cycles. More importantly, the Au-decorated S@Au@SiO2 cathode can deliver a high capacity of 500 mA h g-1 under 5 C.

Nanometer-Thick Films of Aligned ZnO Nanowires Sensitized with Au Nanoparticles for Few-ppb-Level Acetylene Detection

Wireless devices for environmental and health monitoring require the development of stable and highly sensitive thin metal oxide gas-sensing films. This paper reports one-step Langmuir–Blodgett assembly of ultrathin (20 nm) nanostructured films of aligned ZnO nanowires with 10 nm-wide v-grooves on the surface, followed by sensitization with Au nanoparticles (Au NPs) by sputtering and postannealing. The ridges of the nanopatterns are revealed as diffusion barriers capable of preventing Au NPs from sintering via particle migration and growth (PMC). The resulting ZnO Langmuir–Blodgett film decorated with high dispersion of small Au NPs functions as a highly responsive conductance switch, which demonstrates unprecedented sensitivity (37 ppm–1) and detection limit (3 ppb) toward acetylene (C2H2), a key marker gas for air pollution caused by anthropogenic emission. The fabrication method for the stabilized nanometric metal on the Langmuir–Blodgett film reported in this work not only provides a general strategy to improve the sensitivity of the thin sensing film but also can be applied to many metal nanodot-based applications, such as solar cells, plasmon-resonance waveguides, and biosensors.

Improved Electrocatalysis and Electrophoretic Deposition due to the Strong Synergy between Au and Ag Nanoparticles.

AbstractHere we demonstrate that every time Au and Ag NPs are physically mixed together they outperform their monometallic counterparts upon electrocatalysis of hydroquinone (HQ) and electrophoretic deposition (EPD) coverage.We chemically synthesize citrated‐coated Au and Ag nanoparticles (NPs), mix them at the following percent ratios: Au100‐xAgx (Au90Ag10, Au75Ag25, Au50Ag50, Au25Ag75, Au10Ag90), and form films via EPD using HQ as mediate molecule. We encountered good agreement between Optical Extinction Spectroscopy (OES) calculations and Linear Scan Voltammetry (LSV) oxidation peaks which indicated two size populations around ∼2 and 4 nm for Au and 8 nm diameters for Ag NPs. During EPD, HQ electrocatalysis follows the order: Au75Ag25 &gt;Au50Ag50 &gt;Au25Ag75 &gt;Au90Ag10 &gt; Au NPs &gt; Au10Ag90 &gt; Ag NPs. This is remarkable because Au25Ag75 outperforms the Au90Ag10 mixture indicating that “less is more” in the sense that ∼ 70% less Au content in the mixture is more electroactive upon HQ. This suggests that Ag NPs are also playing an important role in the mixture. Also, Au NPs play a role as for example the addition of 10% Au to pure Ag NPs increases more than 3 orders of magnitude the coverage (1.3 x 1012 NPs) with respect to monometallic Ag ( 7.5 x 108 NPs). XPS exhibits electron transfer from Ag to Au NPs which confirms the electronic mechanism in the mixture.Kinetic studies show that the smallest 2 nm diam. Au NPs are responsible for the fastest kinetic due to lower overpotentials. These experiments reveal that small Au NPs (2 nm diam.) and Ag NPs in the mixture team up toward electrocatalysis of HQ which then favors the deposition of NPs by EPD. Fine control on the composition, size, and coverage of deposited metal Au and Ag NPs within the same film are crucial in the design of advanced optoelectronic devices.