skip to main content


Title: Synthesis of Core@Shell Cu‐Ni@Pt‐Cu Nano‐Octahedra and Their Improved MOR Activity
Abstract

Fabrication of 3dmetal‐based core@shell nanocatalysts with engineered Pt‐surfaces provides an effective approach for improving the catalytic performance. The challenges in such preparation include shape control of the 3dmetallic cores and thickness control of the Pt‐based shells. Herein, we report a colloidal seed‐mediated method to prepare octahedral CuNi@Pt‐Cu core@shell nanocrystals using CuNi octahedral cores as the template. By precisely controlling the synthesis conditions including the deposition rate and diffusion rate of the shell‐formation through tuning the capping ligand, reaction temperature, and heating rate, uniform Pt‐based shells can be achieved with a thickness of <1 nm. The resultant carbon‐supported CuNi@Pt‐Cu core@shell nano‐octahedra showed superior activity in electrochemical methanol oxidation reaction (MOR) compared with the commercial Pt/C catalysts and carbon‐supported CuNi@Pt‐Cu nano‐polyhedron counterparts.

 
more » « less
NSF-PAR ID:
10224314
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Angewandte Chemie
Volume:
133
Issue:
14
ISSN:
0044-8249
Page Range / eLocation ID:
p. 7753-7758
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    Fabrication of 3dmetal‐based core@shell nanocatalysts with engineered Pt‐surfaces provides an effective approach for improving the catalytic performance. The challenges in such preparation include shape control of the 3dmetallic cores and thickness control of the Pt‐based shells. Herein, we report a colloidal seed‐mediated method to prepare octahedral CuNi@Pt‐Cu core@shell nanocrystals using CuNi octahedral cores as the template. By precisely controlling the synthesis conditions including the deposition rate and diffusion rate of the shell‐formation through tuning the capping ligand, reaction temperature, and heating rate, uniform Pt‐based shells can be achieved with a thickness of <1 nm. The resultant carbon‐supported CuNi@Pt‐Cu core@shell nano‐octahedra showed superior activity in electrochemical methanol oxidation reaction (MOR) compared with the commercial Pt/C catalysts and carbon‐supported CuNi@Pt‐Cu nano‐polyhedron counterparts.

     
    more » « less
  2. Abstract

    Copper indium sulfide (CIS) colloidal quantum dots (QDs) are a promising candidate for commercially viable QD‐based optical applications, for example as colloidal photocatalysts or in luminescent solar concentrators (LSCs). CIS QDs with good photoluminescence quantum yields (PLQYs) and tunable emission wavelength via size and composition control are previously reported. However, developing an understanding and control over the growth of electronically passivating inorganic shells would enable further improvements of the photophysical properties of CIS QDs. To improve the optical properties of CIS QDs, the focus is on the growth of inorganic shells via the popular metal‐carboxylate/alkane thiol decomposition reaction. 1) The role of Zn‐carboxylate and Zn‐thiolate on the formation of ZnS shells on Cu‐deficient CIS (CDCIS) QDs is studied, 2) this knowledge is leveraged to yield >90% PLQY CDCIS/ZnS core/shell QDs, and 3) a mechanism for ZnS shells grown from zinc‐carboxylate/alkane thiol decomposition is proposed.

     
    more » « less
  3. Abstract

    Engineering the crystal structure of Pt–M (M = transition metal) nanoalloys to chemically ordered ones has drawn increasing attention in oxygen reduction reaction (ORR) electrocatalysis due to their high resistance against M etching in acid. Although Pt–Ni alloy nanoparticles (NPs) have demonstrated respectable initial ORR activity in acid, their stability remains a big challenge due to the fast etching of Ni. In this work, sub‐6 nm monodisperse chemically orderedL10‐Pt–Ni–Co NPs are synthesized for the first time by employing a bifunctional core/shell Pt/NiCoOxprecursor, which could provide abundant O‐vacancies for facilitated Pt/Ni/Co atom diffusion and prevent NP sintering during thermal annealing. Further, Co doping is found to remarkably enhance the ferromagnetism (room temperature coercivity reaching 2.1 kOe) and the consequent chemical ordering ofL10‐Pt–Ni NPs. As a result, the best‐performing carbon supportedL10‐PtNi0.8Co0.2catalyst reveals a half‐wave potential (E1/2) of 0.951 V versus reversible hydrogen electrode in 0.1mHClO4with 23‐times enhancement in mass activity over the commercial Pt/C catalyst along with much improved stability. Density functional theory (DFT) calculations suggest that theL10‐PtNi0.8Co0.2core could tune the surface strain of the Pt shell toward optimized Pt–O binding energy and facilitated reaction rate, thereby improving the ORR electrocatalysis.

     
    more » « less
  4. Abstract

    Reconfigurable hybrid nanoparticles made by decorating flexible polymer shells on rigid inorganic nanoparticle cores can provide a unique means to build stimuli‐responsive functional materials. The polymer shell reconfiguration has been expected to depend on the local core shape details, but limited systematic investigations have been undertaken. Here, two literature methods are adapted to coat either thiol‐terminated polystyrene (PS) or polystyrene‐poly(acrylic acid) (PS‐b‐PAA) shells onto a series of anisotropic gold nanoparticles of shapes not studied previously, including octahedron, concave cube, and bipyramid. These core shapes are complex, rendering shell contours with nanoscale details (e.g., local surface curvature, shell thickness) that are imaged and analyzed quantitatively using the authors' customized analysis codes. It is found that the hybrid nanoparticles based on the chosen core shapes, when coated with the above two polymer shells, exhibit distinct shell segregations upon a variation in solvent polarity or temperature. It is demonstrated for the PS‐b‐PAA‐coated hybrid nanoparticles, the shell segregation is maintained even after a further decoration of the shell periphery with gold seeds; these seeds can potentially facilitate subsequent deposition of other nanostructures to enrich structural and functional diversity. These synthesis, imaging, and analysis methods for the hybrid nanoparticles of anisotropically shaped cores can potentially aid in their predictive design for materials reconfigurable from the bottom up.

     
    more » « less
  5. Abstract

    The nanoscale integration of copper metal, frequently with semiconductor heterostructure interfaces, is a promising route for fabricating new micro‐/nanoelectronic devices. Synthesizing such systems using wet‐chemistry methods requires stabilization of nano‐Cu against corrosion/oxidation, which has proven to be challenging. Here we report a methodology for the facile preparation of Cu@TiO2core‐shell nanowires (NWs). The synthesis combines redox formation of Cu NWs with kinetically controlled hydrolysis of a titania precursor in a single‐pot microwave reaction. The final core‐shell NWs can be precisely tailored with 20‐nm to 140‐nm Cu core diameters, aspect ratios >250, and a 10‐nm porous titania shell. This metal/semiconductor heterojunction is particularly important for its excellent photocatalytic activity. The rapid microwave‐assisted synthesis provides a potentially generalizable paradigm for the rational design of heterogeneous nanostructures with metals and oxides.

     
    more » « less