Ligand-regulated copper nanoclusters: atomic-precision synthesis, structural evolution, and catalytic function in...

Atomically precise copper nanoclusters (Cu NCs) have emerged as molecularly defined platforms that bridge coordination chemistry and heterogeneous catalysis. Owing to the earth abundance of copper, rich redox chemistry, and highly tunable ligand environments, Cu NCs offer attractive alternatives to noble-metal nanoclusters and provide powerful models for correlating atomic structure with catalytic function. In this review, we summarize recent advances in ligand-regulated Cu NCs, focusing on three interconnected aspects including ligand-directed synthesis, atomic-scale structural evolution, and catalytic applications in photocatalysis and electrocatalysis. We discuss how representative ligand systems, including phosphines, thiolates, alkynyls, calixarenes, and chiral ligands, regulate cluster nuclearity, surface coordination, electronic structure, and active-site accessibility. Particular emphasis is placed on how ligand-defined structures influence catalytic performance in two key areas, namely photocatalytic reactions including CO₂ reduction and light-driven C-C/C-N bond formation, and electrocatalytic reactions including CO₂ reduction, oxygen reduction and evolution, hydrogen evolution, and nitrate reduction. Rather than presenting a descriptive catalogue of reported Cu NCs, this review aims to establish a ligand-structure-function framework that clarifies how ligand coordination controls cluster formation, structural evolution, and catalytic behaviour. These insights may guide the rational design of Cu NC catalysts with improved activity, selectivity, and stability.