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Atomically precise nanoclusters of coinage metals in the 1–3 nm size regime have been intensively pursued in recent years. Such nanoclusters are attractive as they fill the gap between small molecules (<1 nm) and regular nanoparticles (>3 nm). This intermediate identity endows nanoclusters with unique physicochemical properties and provides nanochemists opportunities to understand the fundamental science of nanomaterials. Metal nanoparticles are well known to exhibit plasmon resonances upon interaction with light; however, when the particle size is downscaled to the nanocluster regime, the plasmons fade out and step-like absorption spectra characteristic of cluster sizes are manifested due to strong quantum confinement effects. Recent research has revealed that nanoclusters are commonly composed of a distinctive kernel and a surface-protecting shell (or staple-like metal–ligand motifs). Understanding the kernel configuration and evolution is one of the central topics in nanoscience research. This Review summarizes the recent progress in identifying the growth patterns of atomically precise coinage nanoclusters. Several basic kernel units have been observed, such as the M 4 , M 13 and M 14 polyhedrons (where, M = metal atom). Among them, the tetrahedral M 4 and icosahedral M 13 units are the most common ones, which are adopted as building blocks to construct larger kernel structures via various fusion or aggregation modes, including the vertex- and face-sharing mode, the double-strand and alternate single-strand growth, and cyclic fusion of units, as well as the fcc-based cubic growth pattern. The identification of the kernel growth pathways has led to deeper understanding of the evolution of electronic structure and optic properties. 

Abstract This work investigates the critical factors impacting electrochemical CO₂reduction reaction (CO₂RR) using atomically precise Au nanoclusters (NCs) as electrocatalysts. First, the influence of size on CO₂RR is studied by precisely controlling NC size in the 1–2.5 nm regime. We find that the electrocatalytic CO partial current density increases for smaller NCs, but the CO Faradaic efficiency (FE) is not directly associated with the NC size. This indicates that the surface‐to‐volume ratio, i.e. the population of active sites, is the dominant factor for determining the catalytic activity, but the selectivity is not directly impacted by size. Second, we compare the CO₂RR performance of Au₃₈isomers (Au₃₈Q and Au₃₈T) to reveal that structural rearrangement of identical size NCs can lead to significant changes in both CO₂RR activity and selectivity. Au₃₈Q shows higher activity and selectivity towards CO than Au₃₈T, and density functional theory (DFT) calculations reveal that the average formation energy of the key *COOH intermediate on the proposed active sites is significantly lower on Au₃₈Q than Au₃₈T. These results demonstrate how the structural isomerism can impact stabilization of reaction intermediates as well as the overall CO₂RR performance of identical size Au NCs. Overall, this work provides important structure–property relationships for tailoring the NCs for CO₂RR.