Atomically precise Cu14 and Cu13 nanoclusters for the oxygen evolution reaction: one additional Cu atom matters

Abstract

Atomically precise coinage metal nanoclusters have been widely explored as model catalysts to study structure–performance relationships, yet single atom addition to the metal core to tailor the catalytic properties remains challenging. Herein, we report a pair of atomically precise Cu nanoclusters, namely [Cu₁₄(Fur)₃(PPh₃)₈H₁₀]⁺ and [Cu₁₃(Nap)₃(PPh₃)₇H₁₀]⁰ (hereafter referred to as Cu₁₄ and Cu₁₃; Fur: 2-methyl-3-furanthiolate and Nap: 1-naphthalene thiolate), which exhibit an astonishingly high degree of structural similarity, differing merely by the addition of a single Cu atom, yet possessing drastically different catalytic performance toward the oxygen evolution reaction (OER). Specifically, in 1 M KOH solution, Cu₁₄ has a much lower overpotential than Cu₁₃ (306 mV vs. 382 mV) to afford a current density of 10 mA cm⁻², a smaller Tafel slope and a lower charge transfer resistance. Density functional theory calculations were employed to further identify the catalytically active site, confirming that the additional Cu atom in Cu₁₄ is the key catalytic site, which can significantly lower the energy barrier of the rate-determining step in the OER. This study highlights the crucial role of single-atom addition in modulating the properties and functionalities of atomically precise metal nanoclusters, shedding light on future catalyst design.