Programmable kernel structures of atomically precise metal nanoclusters for tailoring catalytic properties

Abstract

The unclear structures and polydispersity of metal nanoparticles (NPs) seriously hamper the identification of the active sites and the construction of structure-reactivity relationships. Fortunately, ligand-protected metal nanoclusters (NCs) with atomically precise structures and monodispersity have become an ideal candidate for understanding the well-defined correlations between structure and catalytic property at an atomic level. The programmable kernel structures of atomically precise metal NCs provide a fantastic chance to modulate their size, shape, atomic arrangement, and electron state by the precise modulating of the number, type, and location of metal atoms. Thus, the special focus of this review highlights the most recent process in tailoring the catalytic activity and selectivity over metal NCs by precisely controlling their kernel structures. This review is expected to shed light on the in-depth understanding of metal NCs' kernel structures and reactivity relationships.

Keywords: atomically precise nanocluster; catalysis; kernel structure; structure‐reactivity relationships.

FIGURE 1

Schematic illustration of the evolution of size‐determined nanoparticles (red: nonmetallic or excitonic, yellow: transition state, blue: metallic or plasmonic). Adapted under the terms of the Creative Commons CC BY license.^{[ 52 ]} Copyright 2016, Springer Nature.

FIGURE 2

(A) Au₂₅ (top), Au₃₈ (middle), and Au₁₄₄ (bottom). (B) Free energy diagrams (ΔG) of the CO₂ reduction to CO. The inset indicated a possible active site. (C) ΔG of the H⁺ reduction to H₂. (D) Illustration of the CO₂ adsorption on the intact and dethiolated Au₂₅ NCs. (E) Projected density of states of the sp‐states (dashed lines) and d‐states (solid lines) of the staple Au in the Au₂₅(SCH₃)₁₈ (black) and Au₂₅(SCH₃)₁₃ (red) NCs. Adapted with permission.^{[ 48 ]} Copyright 2021, Wiley‐VCH. (F) Schematic diagram of Au _n (SG) _m NCs as a catalyst for catalyzing the hydrogenation of 4‐nitrobenzaldehyde. Adapted with permission.^{[ 59 ]} Copyright 2014, American Chemical Society. (G) ln k vs overpotential plots of Au₂₈ (red), Au₃₆ (green), Au₁₃₃ (blue), and Au₂₇₉ (orange). Adapted under the terms of the Creative Commons CC BY license.^{[ 60 ]} Copyright 2018, American Chemical Society.

FIGURE 3

The Au₃₀ kernel and the staple motifs in (A) Au₃₈‐T and (B) Au₃₈‐Q; (C) catalytic activities of Au₂₅, Au₃₈‐T, and Au₃₈‐Q; (D) UV–vis‐NIR spectrum in toluene. Inset: Thin‐layer chromatography of Au₃₈‐T before and after the transformation. Adapted under the terms of the Creative Commons CC BY license.^{[ 70 ]} Copyright 2015, Springer Nature.

FIGURE 4

(A) Structures of Au₂₅ sphere‐ and rod‐shape. (B) Structures of Au₂₅ with the NH₄ ⁺ and SbF₆ ^‒ as counterions. The proposed active sites of ligand removal are circled in black. ΔG values for removal of the ligand (C) and CO₂ reduction to CO (D). Adapted with permission.^{[ 49 ]} Copyright 2018, American Chemical Society.

FIGURE 5

(A) The proposed active sites of NCs structures are circled in black. ΔG for electrochemical (B) CO₂RR and (C) Hydrogen evolution reaction at U = 0 V vs RHE. Adapted with permission.^{[ 93 ]} Copyright 2020, American Chemical Society.

FIGURE 6

(A) Optimized structures of [MAu₂₄(SCH₃)₁₈] ^q clusters. (B) Volcano relation between U _L and ΔG _*OOH for NCs. (C) Volcano plot correlation of the limiting potential as a function of ΔG _*OH. Adapted with permission.^{[ 95 ]} Copyright 2021, American Chemical Society.

FIGURE 7

Structural analysis of (A) Au₄₄(DMBT)₂₈ and (B) Au₃₈Cd₄(DMBT)₃₀ with the Au₂₆ kernels and various motifs. UV–vis‐NIR spectra of (C) Au₄₄(DMBT)₂₈ and (D) Au₃₈Cd₄(DMBT)₃₀. Molecular orbital energy level diagrams for (E) Au₄₄(DMBT)₂₈ and (F) Au₃₈Cd₄(DMBT)₃₀. Adapted under a Creative Commons Attribution 3.0 unported license. Copyright 2021, The Royal Society of Chemistry.

FIGURE 8

(A) Structures analysis of Pt₂Cu₁₈, Cu₁₆(PET)₂₂Cl₄, and Pt₂Cu₃₄ NCs. (B) Catalytic oxidation of silane to silanol (top). Compared to the TiO₂ support at 25°C, catalytic activity enhancement of Cu₃₂@TiO₂ and Pt₂Cu₃₄@TiO₂. Adapted with permission.^{[ 106 ]} Copyright 2021, American Chemical Society.

FIGURE 9

(A) Atomic structures, (B) catalytic performance, and (C) activity reversible behavior of Au₂₄ and Au₂₅. Adapted with permission.^{[ 109 ]} Copyright 2019, Wiley‐VCH. Intramolecular cyclization of (D) 5‐hexyn‐1‐amine and (E) 2‐ethnylaniline over the Au₂₄ and Au₂₅. Adapted with permission.^{[ 50 ]} Copyright 2019, The Royal Society of Chemistry. The catalytic activity of CO₂ hydrogenation over (F) Au₂₄/SiO₂ and (G) Au₂₅/SiO₂ catalysts. Adapted with permission.^{[ 110 ]} Copyright 2020, American Chemical Society.

FIGURE 10

(A,B) Atomic structures of Au_{8 n +4}(SR)_{4 n +8} NCs; (C) Au with (111) (green) and (100) (pink) faces. (D) Catalytic performances of the Au_{8 n +4}(SR)_{4 n +8} catalysts for the hydration of phenylacetylene, Adapted with permission.^{[ 112 ]} Copyright 2019, Wiley‐VCH; and (E) CO₂ hydrogenation. Adapted with permission.^{[ 113 ]} Copyright 2020, Springer Nature.

FIGURE 11

(A) Structure comparison of the Au₂₅(SR)₁₈ ^q . (B) Catalytic performances of the Au₂₅(SR)₁₈ ^q catalysts for intramolecular hydroamination of 2‐ethynylaniline. (C) Recyclability of the spent catalysts in N, N‐dimethylformamide (DMF) in turnover frequency. Adapted with permission.^{[ 119 ]} Copyright 2020, Wiley‐VCH. TOL, toluene; PX, paraxylene.