An official website of the United States government
Bimetallic nanoparticles often show properties superior to their single-component counterparts. However, the large parameter space, including size, structure, composition, and spatial arrangement, impedes the discovery of the best nanoparticles for a given application. High-throughput methods that can control the composition and spatial arrangement of the nanoparticles are desirable for accelerated materials discovery. Herein, we report a methodology for synthesizing bimetallic alloy nanoparticle arrays with precise control over their composition and spatial arrangement. A dual-channel nanopipet is used, and nanofluidic control in the nanopipet further enables precise tuning of the electrodeposition rate of each element, which determines the final composition of the nanoparticle. The composition control is validated by finite element simulation as well as electrochemical and elemental analyses. The scope of the particles demonstrated includes Cu–Ag, Cu–Pt, Au–Pt, Cu–Pb, and Co–Ni. We further demonstrate surface patterning using Cu–Ag alloys with precise control of the location and composition of each pixel. Additionally, combining the nanoparticle alloy synthesis method with scanning electrochemical cell microscopy (SECCM) allows for fast screening of electrocatalysts. The method is generally applicable for synthesizing metal nanoparticles that can be electrodeposited, which is important toward developing automated synthesis and screening systems for accelerated material discovery in electrocatalysis.
more »
« less
Dynamic Ionic Environment Modulation for Precise Electrosynthesis of Heterostructured Bimetallic Nanoparticles
Bimetallic heterostructures, including core–shell and Janus configurations, often offer unique electrocatalytic properties compared to monometallic nanoparticles. However, achieving precise control over both elemental composition and spatial arrangement within these structures remains a challenge. Here, an electrosynthesis method is introduced that enables the fabrication of heterostructured bimetallic nanoparticles with precise, independent control of their elemental distribution. By leveraging dual‐channel scanning electrochemical cell microscopy (SECCM), the local ionic environment is dynamically modulated in situ, adjusting the deposition bias between channels to achieve selective electrodeposition. This approach allows temporal control over the solution conditions within the SECCM droplet, facilitating the synthesis of multi‐layer core–shell nanoparticles with tunable thickness, number, and sequence of layers. This technique is demonstrated with Pt–Cu and Pt–Ni systems, synthesizing arrays of Cu@Pt and Pt@Cu core–shell structures, which are then screened for catalytic activity in hydrogen evolution (HER) and oxygen reduction (ORR) reactions. The high spatial resolution and on‐demand control over the composition and structure make this method well‐suitable for creating arrays of complex, multi‐metallic heterostructures, which is expected to accelerate the discovery of advanced electrocatalytic materials, offering a platform for efficient and scalable electrocatalyst screening.
more »
« less
- Award ID(s):
- 2240113
- PAR ID:
- 10667305
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Advanced Science
- Volume:
- 12
- Issue:
- 17
- ISSN:
- 2198-3844
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
AgCu bimetallic materials have attracted significant interest as catalysts for selective oxidation reactions. Near‐surface alloys of Ag on Cu have been shown to activate O2 efficiently at exposed reverse‐segregated isolated Cu atoms within the surface Ag layers. This study focuses on the synthesis of nanoparticle analogs of these alloys and measurement of their performance for ethylene and propylene epoxidation. Supported Cu/SiO2 catalysts were prepared by strong electrostatic adsorption and partial galvanic replacement of Cu atoms with Ag cations in aqueous media, which led to bimetallic nanoparticles of 3–10 nm average size and 0.25–1.6 Ag:Cu atomic ratios. Galvanic exchange stoichiometry, elemental maps and UV–vis spectroscopy reveal coexistence of Ag and Cu in the nanoparticles. Diffuse reflectance infrared spectra of bound CO indicate the formation of nanoparticles with a Cu core and Ag shell when catalysts with high Ag:Cu ratios are reduced to metallic form. The bimetallic catalysts show improvement over monometallic Ag and Cu and their physical mixtures, exhibiting higher rates, higher initial selectivity than Ag, and resistance to secondary reactions that decrease the selectivity of Cu catalysts at higher alkene conversion. These results demonstrate a simple synthesis method of more selective bimetallic AgCu nanoparticles with core‐shell like structures, which may be of use in a variety of selective oxidation reactions.more » « less
-
Well-ordered nanoparticle arrays are attractive platforms for a variety of analytical applications, but the fabrication of such arrays is generally challenging. Here, it is demonstrated that scanning electrochemical cell microscopy (SECCM) can be used as a powerful, instantly reconfigurable tool for the fabrication of ordered nanoparticle arrays. Using SECCM, Ag nanoparticle arrays were straightforwardly fabricated via electrodeposition at the interface between a substrate electrode and an electrolyte-filled pipet. By dynamically monitoring the currents flowing in an SECCM cell, individual nucleation and growth events could be detected and controlled to yield individual nanoparticles of controlled size. Characterization of the resulting arrays demonstrate that this SECCM-based approach enables spatial control of nanoparticle location comparable with the terminal diameter of the pipet employed and straightforward control over the volume of material deposited at each site within an array. These results provide further evidence for the utility of probe-based electrochemical techniques such as SECCM as tools for surface modification in addition to analysis.more » « less
-
We report a versatile method based on seed-mediated growth for the facile synthesis of trimetallic Pd@PtxAu1−x core-shell nanocubes. By simply varying the feeding ratio between the Pt(II) and Au(III) precursors, the atomic ratio of Pt to Au in the shell and thereby the ensemble state of Pt atoms on the surface can be tuned to control the binding configuration of O2 molecules. Specifically, discrete Pt atoms on the surface promote the adsorption of O2 molecules in the Pauling configuration to enhance the catalytic selectivity of the nanoparticles toward H2O2 via the two-electron oxygen reduction reaction, with the Pd@Pt0.025Au0.975 nanocubes showing selectivity as high as 91% at 0.45 VRHE. This work offers a viable means to augment the electrocatalytic performance of alloy nanocrystals by controlling their surface compositions.more » « less
-
Nanoelectrode ensembles (NEEs), prepared by Au template synthesis, are presented as a proof-of-concept sample platform to study individual electrodeposited materials by scanning electrochemical cell microscopy (SECCM). With this platform, the non-conductive membrane support does not contribute to the electrocatalytic activity recorded at each electrode. Use of low-density template membranes results in electrodes that are isolated because initial membrane pores are typically separated by significant (microscale) distances. Electrodeposition of catalytic nanoparticles onto the electrodes of the array and observation of electrocatalytic activity are demonstrated to be suitable for correlative SECCM voltammetric mapping and electron microscopy. Suitability of NEEs for studies of surface Au oxidation, hydrazine oxidation, and hydrogen evolution (hydrogen evolution reaction, HER), and at Pt particles on NEEs (Pt-NEEs) for HER is demonstrated.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1002/advs.202415727
