Atom-Precise Low-Nuclearity Cluster Catalysis: Opportunities and Challenges

Abstract

Supported low-nuclearity cluster catalysts (LNCCs, for example, the number of metal atoms is 2 ≤ n ≤ 10), between single atoms and nanoclusters in size, possess not only maximum atom efficiency but also highly tunable structures, including nuclearity, composition, local chemical environment, and quantum electronic structures, holding great promise for advanced catalysis in terms of high activity, high selectivity, and high stability at low cost. In contrast to single-atom catalysts, LNCCs can provide multiple adsorption sites and initiate atom−atom synergies within clusters, offering great possibilities to remarkably boost the catalytic reactivity. The electronic structures and catalytic performance of LNCCs can be highly atom dependent. The synthesis of atom-precise LNCCs is vital for catalytic performance optimization and the understanding of structure−activity relationships but remains greatly challenging. This perspective first summarizes the atom-controlled synthetic strategies for atomprecise LNCCs, including size-selected cluster deposition, selected-multinuclear precursor grafting, and atomic layer deposition, and then discusses the state-of-the-art techniques for the statistical structural characterization of atom-precise LNCCs and their atomdependent catalytic properties. Therein, we emphasize the essential roles of prominent electronic and geometric effects as well as atom−atom synergies in the atom-by-atom controlled catalytic performance, particularly activity and stability. Finally, we discuss the opportunities and challenges of LNCCs in heterogeneous catalysis.

Precise control of the catalyst interface at the atomic level

“…122,137,138 Therefore, more detailed characterization is needed, which includes ex situ electron microscopy and extended X-ray absorption spectroscopy, to examine the role of each component. 126,139,140…”

Engineering the spin configuration of electrocatalysts for electrochemical renewable conversions

“…Clusters are aggregates of atoms or molecules, whose structures are between those of discrete atoms and the bulk materials. 170 Compared with the SACs catalysts, the electronic structures of clusters can be approximated as molecular orbitals formed by the hybridization of multiple atoms, which may be a favorable model to study the electronic spin states and electrocatalytic properties. 171,172 Among d-metal clusters, electrons occupy partially filled d-orbital energy levels.…”

Dynamic Behavior of Platinum Atoms and Clusters in the Native Oxide Layer of Aluminum Nanocrystals

“…Controlling the nuclearity, uniformity, and local environment of active metal sites is critical for tuning the reactivity and selectivity of heterogeneous catalysts. Recent efforts have focused on developing synthetic approaches for preparing atomically dispersed and size-controlled precious metal species on oxide support with uniform coordination environments. − One particular challenge that has stimulated keen interest is the control of the distribution of coordination environments in supported metal catalysts. This is crucial for elucidating structure–function relationships and understanding how reaction environments influence metal active site local coordination. , In this context, it is important to investigate how specific chemical environments may be used to control the nuclearity of exposed metal sites.…”