On the Structural Origin of the Catalytic Properties of Inherently Strained Ultrasmall Decahedral Gold Nanoparticles

Abstract

A new mechanism for reactivity of multiply twinned gold nanoparticles resulting from their inherently strained structure provides a further explanation of the surprising catalytic activity of small gold nanoparticles. Atomic defect structural studies of surface strains and quantitative analysis of atomic column displacements in the decahedral structure observed by aberration corrected transmission electron microscopy reveal an average expansion of surface nearest neighbor distances of 5.6%, with many strained by more than 10%. Density functional theory calculations of the resulting modified gold d-band states predict significantly enhanced activity for carbon monoxide oxidation. The new insights have important implications for the applications of nanoparticles in chemical process technology, including for heterogeneous catalysis.

A Highly Active Star Decahedron Cu Nanocatalyst for Hydrocarbon Production at Low Overpotentials

“…We determined the stacking sequence by assigning one layer as A and the subsequent layers as B, C, and so forth. [45,46] The single TB shows the highest tension strain (+1.128%) and the strains tend to decrease with bands of thin twin defects and with stacking faults, consistent with the stress release mechanism. All measured strains near the edge of the SD-Cu NPs show tension strains while strains near the center of the SD-Cu show compression strains except for the case of a single TB (location 3), which is consistent with measured strains in the 2D projection TEM reported for gold decahedron NPs.…”

Less Noble or More Noble: How Strain Affects the Binding of Oxygen on Gold

“…[11] Thea dsorption of oxygen species on gold is of interest in this context, in part because the impact of strain may contribute to the unexpected reactivity of gold surfaces when in the form of small clusters or nanoporous materials. [12][13][14][15] Ab initio density functional theory indicates that an increase in the in-plane lattice parameter makes Au surfaces bind oxygen more strongly;inother words,tensile tangential strain makes Au less noble. [16] Experiments have confirmed this prediction, both through ad irect measurement of the shift in the electrode potential with strain during oxygen species electrosorption on Au, [17] and more indirectly through the observation that surface stress becomes more negative when oxygen species adsorb on the highly curved surfaces of nanoporous Au.…”

Synthesis and Structural Characterization of Ferromagnetic Au/Co Nanoparticles

“…The decahedral nanostructure presents very interesting phenomena as explained in previous reports. 19,20 Figure 2a shows the same decahedron structure presented in Figure 1b, each tetrahedron (R1, R2, R3, R4 and R5) is separated by arrows as shown in Figure 2a. The Zcontrast image showed different contrasts for Au and Co, revealing the possible atom reach positions in the nanostructure.…”