Bimetallic Nanocrystals Research Articles

Ligand and hard base assisted preparation of AgInS2 single phase nanocrystals for enhancing the photocatalytic activity of TiO2

As a typical sulfide bimetallic semiconductor material, AgInS2 has been widely studied for its excellent photoelectrochemical properties. However, due to the large lattice mismatch, it is difficult to obtain AgInS2 single phase nanocrystals by conventional reaction. Therefore, the ligand and pH were selected and adjusted for the preparation of AgInS2 single phase nanocrystals. Adding organic molecules containing sulfhydryl groups as ligands could combine with metal ions to form covalent bonds, while OH− could react with transition metal ions to form soluble metal hydroxides, which could protect metal ions from direct reaction with S2−. With the help of x-ray powder diffraction, AgInS2 single phase nanocrystals were successfully prepared by hydrothermal reaction at 180 °C with L-cysteine (L-Cys) or glutathione as the ligand in an alkaline environment. Finally, it was determined that the AgInS2 single phase nanocrystals obtained when the ligand was L-Cys and the reaction time was locked to 24 h had high catalytic activity as determined by a rhodamine B (RhB) removal experiment. In addition, AgInS2/TiO2 (AIS-TO) heterojunction photocatalysts were prepared by an in-situ hydrothermal method to improve the photocatalytic activity of TiO2. Among them, the 5% AIS-TO sample showed the highest catalytic activity, and the degradation rate of RhB was 2.4 times that of TiO2. It was also proved that electrons were transported by a Z-type mechanism in the AIS-TO heterojunction photocatalytic system. This work would provide a feasible scheme for the preparation of more sulfide bimetallic semiconductor single phase nanocrystals.

Charge transfer uplift in dye-sensitized solar cells using fibrous nanocrystals of platinum-based bimetallic counter electrodes

Charge transfer dynamic on the surface of a counter electrode (CE) of dye-sensitized solar cells (DSSC) during a photoactivation process relates to the physicochemical properties of the CE. In this paper, we investigated how the co-metal element in the Pt-based bimetallic fibrous nanocrystals (FNC) CE influences the charge transfer dynamic of the dye-sensitized solar cell (DSSC) devices. We discovered that the interfacial charge transfer resistance decreases dramatically in bimetallic CEs if compared with the pristine Pt. For example, it decreases more than 5 times in the AuPt FNC and more than 4 times lower in the AgPt and PdPt FNC CEs. This phenomenon then induced an enhanced carrier diffusion in the device that is reflected by the decrease in the carrier diffusion resistance and the improvement of the carrier lifetime in the device using bimetallic CEs. The DSSCs using the champion CEs, that is AuPt, can produce a short circuit current (Jsc), open-circuit voltage (Voc), and fill factor (FF) as high as 10.63 mAcm−2, 1.00 V, and 0.43, respectively, which correspond to a power conversion efficiency (PCE) of 4.60%. This PCE is approximately 3.5 times higher if compared with the DSSC using the pristine Pt CE. The enhancement of the surface physicochemical properties of the CE due to the bimetallization process is assumed as the key factor for the performance enhancement, the facts that are verified by the X-ray photoelectron spectroscopy and the electrochemical properties analysis results. The synthesis and the device characterization are discussed in detail.

Atomistic insights into the nucleation and growth of platinum on palladium nanocrystals

Despite the large number of reports on colloidal nanocrystals, very little is known about the mechanistic details in terms of nucleation and growth at the atomistic level. Taking bimetallic core-shell nanocrystals as an example, here we integrate in situ liquid-cell transmission electron microscopy with first-principles calculations to shed light on the atomistic details involved in the nucleation and growth of Pt on Pd cubic seeds. We elucidate the roles played by key synthesis parameters, including capping agent and precursor concentration, in controlling the nucleation site, diffusion path, and growth pattern of the Pt atoms. When the faces of a cubic seed are capped by Br−, Pt atoms preferentially nucleate from corners and then diffuse to edges and faces for the creation of a uniform shell. The diffusion does not occur until the Pt deposited at the corner has reached a threshold thickness. At a high concentration of the precursor, self-nucleation takes place and the Pt clusters then randomly attach to the surface of a seed for the formation of a non-uniform shell. These atomistic insights offer a general guideline for the rational synthesis of nanocrystals with diverse compositions, structures, shapes, and related properties.

Hyper-dendritic PdZn nanocrystals as highly stable and efficient bifunctional electrocatalysts towards oxygen reduction and ethanol oxidation

Although attentions have been devoted to developing Pd-based bimetallic nanocrystals towards the electrocatalytic oxygen reduction reaction (ORR) and ethanol oxidation reaction (EOR), the engineering of efficient bifunctional electrocatalysts with high atomic utilization still faces big challenges. Herein, we reported a facile one-pot template-free route to fabricate three-dimension hyper-dendritic PdZn nanocrystals (HD-PdZn NCs) that regulated by gas mixtures of carbon monoxide and hydrogen. The developed catalysts acted as robust bifunctional electrocatalysts for cathodic ORR and anodic EOR. Specifically, the engineered HD-PdZn NCs not only displayed superior mass activity (MA, 0.461 A mgPd-1) and specific activity (SA, 0.393 mA cm−2) at 0.9 V, which were 5.2 and 5.0 times of commercial Pt/C, respectively, but also showed enhanced stability with only 3% loss of MA after 10,000 cycles for ORR. Density functional theory (DFT) calculations revealed the Zn implantation could facilitate the reduction of OOH* to OH* on the surface of Pd during the ORR process. Moreover, HD-PdZn NCs exhibited the highest EOR mass activity with a value of 3.45 A mgPd−1 among benchmarked catalysts in alkaline solution. The advantageous structural features and electron effects are proposed to be responsible for the remarkable bifunctional activities. This work illustrates a facile method to fabricate highly efficient bifunctional electrocatalyst for energy conversation application.

Pt-Co@Pt Octahedral Nanocrystals: Enhancing Their Activity and Durability toward Oxygen Reduction with an Intermetallic Core and an Ultrathin Shell.

Despite extensive efforts devoted to the synthesis of Pt-Co bimetallic nanocrystals for fuel cell and related applications, it remains a challenge to simultaneously control atomic arrangements in the bulk and on the surface. Here we report a synthesis of Pt-Co@Pt octahedral nanocrystals that feature an intermetallic, face-centered tetragonal Pt-Co core and an ultrathin Pt shell, together with the dominance of {111} facets on the surface. When evaluated as a catalyst toward the oxygen reduction reaction (ORR), the nanocrystals delivered a mass activity of 2.82 A mg-1 and a specific activity of 9.16 mA cm-2, which were enhanced by 13.4 and 29.5 times, respectively, relative to the values of a commercial Pt/C catalyst. More significantly, the mass activity of the nanocrystals only dropped 21% after undergoing 30 000 cycles of accelerated durability test, promising an outstanding catalyst with optimal performance for ORR and related reactions.

Yolk@Shell Nanoreactors Carrying a Cluster of Metal Nanocrystals Stabilized Inside the Hollow Carbon Shell

Synthesis and stabilization of ultrasmall metal nanocrystals at high temperature have always been challenging due to their self‐aggregating behavior. Here, we introduce a strategy to synthesize a cluster of tiny metal nanocrystals (~3 nm) inside a hollow carbon shell as yolk@shell‐type architecture following a metal‐coordination‐based nanocrystal stabilization at high temperature (500 °C). The successful catalytic reduction of 2‐amino‐4‐nitrophenol demonstrates the efficiency of such nanoreactor in chemical transformation. Further adaptation of this strategy helps in synthesizing bimetallic (Au/Pt, Au/Pd, and Au/Ru) nanocrystals, which unfolds the possibilities to design advanced new‐generation catalysts.

Tubular CoFeP@CN as a Mott–Schottky Catalyst with Multiple Adsorption Sites for Robust Lithium−Sulfur Batteries

AbstractThe shuttle effect and the sluggish reaction kinetics of lithium polysulfide (LiPS) seriously compromise the performance of lithium–sulfur batteries (LSBs). To overcome these limitations and enable the fabrication of robust LSBs, here the use of a Mott–Schottky catalyst based on bimetallic phosphide CoFeP nanocrystals supported on carbon nitride tubular nanostructures as sulfur hosts is proposed. Theoretical calculations and experimental data confirm that CoFeP@CN composites are characterized by a suitable electronic structure and charge rearrangement that allows them to act as a Mott–Schottky catalyst to accelerate LiPS conversion. In addition, the tubular geometry of CoFeP@CN composites facilitates the diffusion of Li ions, accommodates volume change during the reaction, and offers abundant lithiophilic/sulfiphilic sites to effectively trap soluble LiPS. Therefore, S@CoFeP@CN electrodes deliver a superior rate performance of 630 mAh g−1 at 5 C, and remarkable cycling stability with 90.44% capacity retention over 700 cycles. Coin cells with high sulfur loading, 4.1 mg cm−2, and pouch cells with 0.1 Ah capacities are further produced to validate their superior cycling stability. In addition, it is demonstrated here that CoFeP@CN hosts greatly alleviate the often overlooked issues of low energy efficiency and serious self‐discharging in LSBs.

Preparation and Investigation of Pd and Bimetallic Pd-Sn Nanocrystals on γ-Al2O3

One of the key factors for producing highly dispersed controlled nanoparticles is the method used for metal deposition. The decomposition of metal-organic precursors is a good method for deposition of metal nanoparticles with very small sizes and narrow size distributions on the surface of various supports. The preparation process of Pd and bimetallic Pd-Sn nanoparticles supported onto γ-Al2O3 is considered. The samples were prepared by diffusional co-impregnation of the γ-Al2O3 support by using organometallic Pd(acac)2 and Sn(acac)2Cl2 precursors. To achieve the formation of Pd and bimetallic Pd-Sn nanoparticles on the support surface, the synthesized samples were then subjected to thermal decomposition under Ar (to decompose the organometallic bound to the surface while keeping the formed nanoparticles small) followed by an oxidation in O2 (to eliminate the organic compounds remaining on the surface) and a reduction in H2 (to reduce the nanoparticles oxidized during the previous step). A combination of methods (ICP-OES, TPR-H2, XPS, TEM/EDX) was used to compare the physical-chemical properties of the synthesized Pd and bimetallic Pd-Sn nanoparticles supported on the γ-Al2O3. The three samples exhibit narrow size distribution with a majority on nanoparticles between 3 and 5 nm. Local EDX measurements clearly showed that the nanoparticles are bimetallic with the expected chemical composition and the measured global composition by ICP-OES. The surface composition and electronic properties of Pd and Sn on the γ-Al2O3 support were investigated by XPS, in particular the chemical state of palladium and tin after each step of thermal decomposition treatments (oxidation, reduction) by the XPS method has been carried out. The reducibility of the prepared bimetallic nanoparticles was measured by hydrogen temperature programmed reduction (TPR-H2). The temperature programmed reduction TPR-H2 experiments have confirmed the existence of strong surface interactions between Pd and Sn, as evidenced by hydrogen spillover of Pd to Sn (Pd-assisted reduction of oxygen precovered Sn). These results lead us to propose a mechanism for the formation of the bimetallic nanoparticles.

Defective PdRh bimetallic nanocrystals enable enhanced methanol electrooxidation

Although PdRh-based bimetallic nanocrystals have been demonstrated as effective catalysts for methanol electrooxidation, the impact of introduced Rh on CO poisoning resistance and consequently the catalytic activity is still lacking in-depth studies. In this work, defective PdRh bimetallic nanocrystals (PdRh NAs) with different composition ratios are synthesized. The prepared Pd3Rh1 NAs exhibit much higher peak current density and greater durability in comparison with the control sample of Pd1Rh1 NAs, Pd5Rh1 NAs, and the Commercial Pd/C. In addition, we observe that the introduced suitable amount of Rh plays a critical role in promoting the activity and stability of PdRh NAs for methanol electrooxidation reaction (MOR). This work provides an advanced MOR catalyst, and highlights that modulating both surface structure and chemical composition of catalysts is an effective route to realize catalytic property optimization.

Highly Porous Au-Pt Bimetallic Urchin-Like Nanocrystals for Efficient Electrochemical Methanol Oxidation.

Highly porous Au–Pt urchin-like bimetallic nanocrystals have been prepared by a one-pot wet-chemical synthesis method. The porosity of urchin-like bimetallic nanocrystals was controlled by amounts of hydrazine used as reductant. The prepared highly porous Au-Pt urchin-like nanocrystals were superior catalysts of electrochemical methanol oxidation due to high porosity and surface active sites by their unique morphology. This approach will pave the way for the design of bimetallic porous materials with unprecedented functions.

Ir-Ni based mono and bimetallic nanocrystals: synthesis, characterization and effect of cationic, anionic, and non-ionic stabilizers

Nickel based bimetallic nanocrystals, iridium-nickel play an imperative role in catalysis, electrocatalysis, and magnetic applications. In the present work Ir-Ni bimetallic nanoalloys were synthesized by modified polyol reduction method with different cationic, anionic, and non-ionic surface active agents like CTAB, SDS, TSC, and PVP. The non-ionic surface active agent PVP produced a better effect on nanoparticle size than cationic and anionic surfactants. The synthesized bimetallic nanocrystals were characterized by UV-Vis, XRD, FTIR, FESEM, and HRTEM techniques. XRD and FTIR verify the nature of synthesized bimetallic nanocrystals and the interaction between stabilizers and nanoparticles. HRTEM studies reveal that the PVP stabilized Ir-Ni (3:1) and Ir-Ni (1:1) bimetallic nanocrystals are small in size and less dispersed. Particle size range of these nanoparticles is from (1.77-2.36) nm. FESEM images show that nanoparticles are in quasi spherical shape. EDX analysis indicates that the resultant particles are core shell structure with Ni core and Ir shell.

Laser assisted synthesis of anisotropic metal nanocrystals and strong light-matter coupling in decahedral bimetallic nanocrystals.

The advances in colloid chemistry and nanofabrication allowed us to synthesize noble monometallic and bimetallic nanocrystals with tunable optical properties in the visible and near infrared region of the electromagnetic spectrum. In the strong coupling regime, surface plasmon polaritons (SPPs) of metal nanoparticles interact with excitons of quantum dots or organic dyes and plasmon–exciton hybrid states called plexcitons are formed. Until now, various shaped metal nanoparticles such as nanorods, core–shell nanoparticles, hollow nanoparticles, nanoprisms, nanodisks, nanorings, and nanobipyramids have been synthesized to generate plasmon–exciton mixed states. However, in order to boost plasmon–exciton interaction at nanoscale dimensions and expand the application of plexcitonic nanocrystals in a variety of fields such as solar cells, light emitting diodes, and nanolasers, new plexcitonic nanocrystals with outstanding optical and chemical properties remain a key goal and challenge. Here we report laser-assisted synthesis of decahedral shaped noble metal nanocrystals, tuning optical properties of the decahedral shaped nanocrystals by galvanic replacement reactions, colloidal synthesis of bimetallic decahedral shaped plexcitonic nanocrystals, and strong plasmon–plasmon interaction in bimetallic decahedral shaped noble metal nanocrystals near a metal film. We photochemically synthesize decahedral Ag nanoparticles from spherical silver nanoparticles by using a 488 nm laser. The laser assisted synthesis of silver nanoparticles yields decahedral (bicolored) and prism (monocolored) shaped silver nanocrystals. The decahedral shaped nanoparticles were selectively separated from prism shaped nanoparticles by centrifugation. The optical properties of decahedral nanocrystals were tuned by the galvanic replacement reaction between gold ions and silver atoms. Excitons of J-aggregate dyes and SPPs of decahedral bimetallic nanoparticles strongly couple and hence decahedral shaped plexcitonic nanoparticles are prepared. In addition, localized SPPs of decahedral shaped bimetallic nanocrystals interact strongly with the propagating SPPs of a flat silver film and hence new hybrid plasmonic modes (plasmonic nanocavities) are generated. The experimental results are further fully corroborated by theoretical calculations including decahedral shaped plexcitonic nanoparticles and decahedral nanoparticles coupled to flat metal films.

Kinetically Controlled Synthesis of Pd–Cu Janus Nanocrystals with Enriched Surface Structures and Enhanced Catalytic Activities toward CO2 Reduction

Bimetallic nanocrystals often outperform their monometallic counterparts in catalysis as a result of the electronic coupling and geometric effect arising from two different metals. Here we report a facile synthesis of Pd-Cu Janus nanocrystals with controlled shapes through site-selected growth by reducing the Cu(II) precursor with glucose in the presence of hexadecylamine and Pd icosahedral seeds. Specifically, at a slow reduction rate, the Cu atoms nucleate and grow from one vertex of the icosahedral seed to form a penta-twinned Janus nanocrystal in the shape of a pentagonal bipyramid or decahedron. At a fast reduction rate, in contrast, the Cu atoms can directly nucleate from or diffuse to the edge of the icosahedral seed for the generation of a singly twinned Janus nanocrystal in the shape of a truncated bitetrahedron. The segregation of two elements and the presence of twin boundaries on the surface make the Pd-Cu Janus nanocrystals effective catalysts for the electrochemical reduction of CO2. An onset potential as low as -0.7 VRHE (RHE: reversible hydrogen electrode) was achieved for C2+ products in 0.5 M KHCO3 solution, together with a faradaic efficiency approaching 51.0% at -1.0 VRHE. Density functional theory and Pourbaix phase diagram studies demonstrated that the high CO coverage on the Pd sites (either metallic or hydride form) during electrocatalysis enabled the spillover of CO to the Cu sites toward subsequent C-C coupling, promoting the formation of C2+ species. This work offers insights for the rational fabrication of bimetallic nanocrystals featuring desired compositions, shapes, and twin structures for catalytic applications.

Plasmonic sensing of Cu2+ via shell-etching of Au@Ag nanorods

Bimetallic nanocrystals are widely used in plasmonic sensors owing to the wide-range tunable surface plasmon resonance peak. Here, a Au@Ag core-shell nanorod is demonstrated as a plasmonic sensor to realize Cu2+ detection via nanorod shell etching. The Cu2+ concentration can be easily detected by observing the color of the solution containing Au@Ag nanorods. A relatively low detection limit of 1.3 μM is obtained by monitoring the extinction spectra. The Au@Ag bimetallic plasmonic sensor exhibits a high sensitivity for Cu2+ detection and also excludes interference from other prevalent ions in the solution. This work exhibits an excellent example of the application of shell-etching for heavy metal ion detection, which provides a potential application in biology and environmental monitoring fields.

Synthesis of highly porous polymer microspheres with interconnected open pores for catalytic microreactors

• A synthetic method for producing highly porous PS microspheres was developed. • The porous PS microspheres had interconnective open pores. • PS seed particles were dispersed in different types of oil-in-water emulsions. • Catalytic microreactors were fabricated by using the porous PS microspheres. • The microreactors exhibited extremely high catalytic activity. Porous polymer microspheres with interconnective open pores have attracted significant interest, owing to their unique properties as compared to those of traditional microspheres. However, developing a facile synthetic method to produce these unique particles remains a challenge. Herein, a method is proposed to produce highly porous polystyrene (PS) microspheres with interconnective open pores and a uniform size distribution, which were prepared by simply dispersing PS seed particles in an oil-in-water emulsion system. The morphological evolutions of the PS microspheres exposed to different types of oil-in-water emulsions were systematically investigated, and the relationship between the colloidal stability of the emulsions and the final structure of the PS microspheres was studied. Based on these results, the best oil-in-water system for synthesizing highly porous PS microspheres with interconnected open pores was found. The proposed synthetic method was demonstrated to offer significant advantages over previously developed techniques; it was simple, fast, and easy to process, and did not require special additives such as surfactants, complex techniques, etching processes to generate pores, and sophisticated equipment. Catalytic microreactors were fabricated by synthesizing mono- and bimetallic nanocrystals on the surface of the porous microspheres via in situ chemical reduction. When the microreactors were used as a heterogenous catalyst for the 4-nitrophenol (4-NP) reduction reaction by sodium borohydride (NaBH 4 ), they exhibited extremely high catalytic activity and excellent recyclability. These results demonstrated that the highly porous microspheres have very high porosity, huge surface area per unit volume, and good chemical stability, indicating their great potentials as a supporting material for practical applications in catalysis.

Novel bimetallic Ag-Fe MOF for exceptional Cd and Cu removal and 3,4-dihydropyrimidinone synthesis

Removing heavy metals from aqueous solutions has drawn the attention of scientists due to their serious global health challenges to human society. Thus, it is very important to use an adsorbent with a high removal efficiency of heavy metals and has the advantage of low-cost. In the present work, metal-organic framework with tailored components is very important in attaining the required purpose and expanding the developing applications. Herein, bimetallic Ag-Fe metal-organic framework has been successfully synthesized through a solvothermal method and characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Scanning electron microscopy, Transmission electron microscopy and surface area measurements. Due to the synergistic contribution between Ag and Fe, bimetallic Ag-Fe metal-organic frameworks nanocrystals exhibit enhanced decontamination performance toward the removal of heavy metal ions with ultra-fast adsorption kinetics and high adsorption values. Impressively, an extraordinary Cadmium (II) and Copper (II) adsorption values up to 265 and 213 mg/g, respectively are obtained in bimetallic (0.6:1) Ag-Fe metal-organic framework, which considers the superior adsorbent between the prepared metal-organic frameworks. The surface acidity, examined through the nonaqueous potentiometric titration of n-butylamine, was found to be increased by the formation of a bimetallic metal-organic framework as well as the catalytic activity. Among various Ag: Fe, the ratio (0.6:1) showed the highest acidity and catalytic activity towards the synthesis of 3,4-dihydropyrimidinone. The metal-organic frameworks catalysts were found to maintain their adsorption capacity and catalytic activity even after four-time reusing.

Engineering the composition of bimetallic nanocrystals to improve hydrodeoxygenation selectivity for 2-acetylfuran

Hydrodeoxygenation (HDO) of 2-acetylfuran (2-AF) was examined at 473 K and 33 bar over carbon-supported, bimetallic catalysts. Monodispersed, Pt-based (PtNi, PtCo, and PtCu) and Ni-based (NiCu) nanocrystals (NCs) with well-defined sizes and compositions were prepared via colloidal synthesis. Steady-state, flow-reactor measurements demonstrate that selectivities for HDO reaction to 2-ethylfuran (2-EF) are strongly dependent on the alloy compositions. The HDO of 2-AF is shown to be sequential, where 2-EF can react further to form over-hydrogenated products. The NiCu3/C nanocatalyst was superior to the other bimetallics; with the optimal residence time, it achieved a selectivity of 75 % 2-EF with 80 % conversion of 2-AF, with good stability for up to at least five hours time-on-stream. Deactivation due to coking became an issue when the NCs were deposited on oxide supports with weak acidity (SiO2 and γ-Al2O3). This work provides insights into which bimetallic catalytic systems might be useful for HDO of 2-AF reaction.

Fabrication and Characterization of Biplasmonic Substrates Obtained by Picosecond Laser Pulses

Bimetallic nanostructures have the potential to become the new generation candidates for applications in catalysis, electronics, optoelectronics, biosensors and also for surface-enhanced Raman Spectroscopy (SERS). The bimetallic nanocrystals offer additional properties over the single metal components such as improved electromagnetic properties and corrosion protection. This work presents a simple and inexpensive method to fabricate large area biplasmonic (bimetallic) substrates, employing DC magnetron sputtering, picosecond laser pulses and a digital galvanometric scanner. The aim of this study was to achieve large area homogeneous substrates while having a good and predictable signal amplification by SERS effect. Gold thin films with 200 nm thickness were deposited on optical polished substrates and then irradiated in atmospheric air with λ = 1064 nm wavelength laser pulses with 8 ps pulse duration and 500 kHz fixed repetition rate. Various laser fluences and laser irradiation speeds were employed in order to optimize the Laser-Induced Periodic Surface Structures (LIPSS) formed on the substrate. The results are presented comparatively for the standalone Cu substrates and for the Cu-Au substrates using Raman spectral analysis on a single signal peak of a Rhodamine 6G solution.

Effects of Strain and Kinetics on the H2O2-Assisted Reconstruction of Ag-Au-Ag Nanorods.

Morphology of Ag nanocrystals (NCs) is essential to the NC application in catalysis, optics, and as antibacterial agents. Therefore, it is important to develop synthetic methods and understand the evaluation of NC morphology in different chemical environments. In this study, we report interesting findings of the morphological change of fivefold-twinned Ag–Au–Ag nanorods (NRs) under the effect of H2O2 both as an oxidant (etchant) and a reductant. At low H2O2 concentration, the reconstruction of Ag–Au–Ag NRs was dominated by the growth along the longitudinal direction of NRs. With the increase of H2O2 concentration, the reconstruction also occurs in the transverse direction, and a clear change in particle morphology was observed. We further systematically studied the mechanism of the reaction. The results showed that the transition of the morphology was a two-step process: (1) the etching of Ag on the seeds and (2) the reduction of Ag2O. In the second step, the reaction kinetics was highly affected by H2O2 concentration. At low H2O2 concentration, the growth mainly occurs along ⟨110⟩. However, at high H2O2 concentration, the reduction of Ag was not facet-selective. Using the developed method, we can prepare various bimetallic NCs (high aspect ratio NRs with abundant pinholes, nanoplates, and other NCs). The effect of the reconstruction process on the surface-enhanced Raman scattering (SERS) performance of NCs was investigated.

Establishing Flask-Relevant Reaction Conditions for Imaging Bimetallic Nanocrystal Formation with Liquid Phase Transmission Electron Microscopy

Establishing Flask-Relevant Reaction Conditions for Imaging Bimetallic Nanocrystal Formation with Liquid Phase Transmission Electron Microscopy