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Colloidal hybrid nanoparticles contain multiple nanoscale domains fused together by solid-state interfaces. They represent an emerging class of multifunctional lab-on-a-particle architectures that underpin future advances in solar energy conversion, fuel-cell catalysis, medical imaging and therapy, and electronics. The complexity of these ‘artificial molecules’ is limited ultimately by the lack of a mechanism-driven design framework. Here, we show that known chemical reactions can be applied in a predictable and stepwise manner to build complex hybrid nanoparticle architectures that include
M–Pt–Fe O 3 ( 4 M = Au, Ag, Ni, Pd) heterotrimers, M S–Au–Pt–Fe x O 3 ( 4 M = Pb, Cu) heterotetramers and higher-order oligomers based on the heterotrimeric Au–Pt–Fe O 3 building block. This synthetic framework conceptually mimics the total-synthesis approach used by chemists to construct complex organic molecules. The reaction toolkit applies solid-state nanoparticle analogues of chemoselective reactions, regiospecificity, coupling reactions and molecular substituent effects to the construction of exceptionally complex hybrid nanoparticle oligomers. 4
Figures at a glance
Figure 1: Stepwise construction of M–Pt–Fe O 3 heterotrimers ( 4 M = Ag, Au, Ni, Pd).
a, Schematic showing the multistep synthesis of M–Pt–Fe O 3 heterotrimers, along with the most significant possible products and their observed frequencies (expressed as the percentage of observed heterotrimers, not total yield). Representative TEM images show 4 Pt nanoparticle seeds ( b), Pt–Fe O 3 heterodimers ( 4 c) and Au–Pt–Fe O 3 ( 4 d), Ag–Pt–Fe O 3 ( 4 e), Ni–Pt–Fe O 3 ( 4 f) and Pd–Pt–Fe O 3 ( 4 g) heterotrimers. All scale bars are 25 nm. h, Photographs of a vial that contains Au–Pt–Fe O 3 heterotrimers in 4 hexane (left), which responds to an external Nd–Fe–B magnet, the same vial with Au–Pt–Fe O 3 heterotrimers in a larger volume of hexanes (middle) and the same vial after precipitation of the heterotrimers with 4 ethanol (right). The precipitated heterotrimers collect next to the external magnet.
Figure 2: Characterization data for M–Pt–Fe O 3 heterotrimers ( 4 M = Au, Ag, Ni, Pd).
a, Powder XRD data for all of the M–Pt–Fe O 3 heterotrimers and of the Pt–Fe 4 O 3 heterodimer for comparison. 4 b, EDS spectra for all of the M–Pt–Fe O 3 heterotrimers. For the Au–Pt–Fe 4 O 3 and Ag–Pt–Fe 4 O 3 samples, a Ni TEM grid was used and the Ni and Cu signals originated from this grid. For the Ni–Pt–Fe 4 O 3 and Pd–Pt–Fe 4 O 3 samples, a Cu TEM grid was used and the Cu signal originated from this grid. 4 c, SAED patterns for all of the M–Pt–Fe O 3 heterotrimers show distinct diffraction spots or rings for each of the components. 4 d, UV-vis absorption spectra for the Au–Pt–Fe O 3 and Ag–Pt–Fe 4 O 3 heterotrimers, and also reference spectra for 4 Au and Ag nanoparticles and the Pt–Fe O 3 heterodimers. a.u. = arbitrary units. 4
Figure 3: Chemoselective nucleation in the Ag–Pt–Fe O 3 heterotrimer system. 4
a– d, TEM images and corresponding schematics showing a series of control experiments, all carried out under the same reaction conditions and designed to probe the chemoselectivity of heterogeneous nucleation in the prototype Ag–Pt–Fe O 3 system: nucleation of Ag on 4 Fe nanoparticles ( O 3 4 a), nucleation of Ag on Pt nanoparticles ( b), nucleation of Ag on both Fe and O 3 4 Pt nanoparticles that are present as a physical mixture ( c) and nucleation of Ag exclusively on the Pt domain of Pt–Fe O 3 nanoparticles that are present as interconnected dimers with a solid-state interface ( 4 d). The insets in ( b) and ( c) show enlarged views of the regions indicated by boxes to highlight the lower-contrast Ag regions that nucleate on the higher-contrast Pt particles. The scale bars in the main panels correspond to 20 nm and those in the insets correspond to 5 nm. e, Pt XPS spectra for Pt–Fe 4 f O 3 heterodimers and the corresponding 4 Pt seeds, which indicate a decreased binding energy in the heterodimers.
Figure 4: Stepwise construction of M S x –Au–Pt–Fe y O 3 heterotetramers ( 4 M = Cu, Pb).
a, Schematic showing the stepwise construction of M S x –Au–Pt–Fe y O 3 heterotetramers, along with the most significant possible products and their observed frequencies (expressed as the percentage of observed heterotetramers, not total yield). 4 b, c, Representative TEM images of Cu S 9 –Au–Pt–Fe 5 O 3 heterotetramers, with enlarged regions in ( 4 c) showing lattice fringes that correspond to the Fe (311), Cu O 3 4 S 9 (200), Cu 5 S 9 (111), 5 Au (111) and Pt (111) planes. d, e, Powder XRD data for the Cu S 9 –Au–Pt–Fe 5 O 3 ( 4 d) and PbS–Au–Pt–Fe O 3 ( 4 e) heterotetramers, along with a pattern for Cu S 9 –Au heterodimers in ( 5 d) for comparison. f, A representative TEM image of the PbS–Au–Pt–Fe O 3 heterotetramers. 4 g, The composite EDS element map for a single PbS–Au–Pt–Fe O 3 heterotetramer particle includes an overlay of Fe (red), Pt (green), Au (blue) and Pb (orange). 4 h– m, A STEM image of a single Cu S 9 –Au–Pt–Fe 5 O 3 heterotetramer ( 4 h), along with the corresponding EDS element maps for Fe ( i), Pt ( j), Au ( k), Cu ( l) and superimposed Fe, Pt, Au and Cu ( m). The scale bars correspond to 25 nm ( b), 5 nm ( c, h) and 10 nm ( f).
Figure 5: Higher-order hetero-oligomers based on the Au–Pt–Fe O 3 heterotrimer building block. 4