Atomically Precise Platinum Nanoclusters: History and Recent Advances in Synthesis, Structure, and Properties

Platinum is a cornerstone catalyst for various chemical and electrochemical transformations. Atomically precise platinum nanoclusters, located at the transition stage between smaller platinum-ligand coordination molecules (<∼1 nm) and larger platinum colloidal nanoparticles (>∼3 nm), can combine the advantages of both homogeneous and heterogeneous catalysts, serving as model systems for understanding catalytic processes. However, compared to significant advances in coinage metal nanoclusters, atomically precise platinum nanoclusters remain largely unexplored. Here, we introduce the rich history and highlight the recent renaissance of atomically precise Pt clusters, focusing on their synthesis, structures, and properties. We discuss (i) how the sizes can be precisely controlled through the redox chemistry of one-dimensional platinum carbonyl clusters, (ii) how the core structures can be diversified in three-dimensional Pt_n(CO)_m clusters, (iii) how the surface properties can be tailored by using various types of ligands, and (iv) recent progress in evaluating these clusters in electrochemical and thermal catalytic reactions. By bridging the gaps among conventional coordination, cluster, colloidal, and catalytic chemistry, we expect to provide some fundamental insights that are crucial for designing more efficient platinum cluster catalysts with atomic precision.