Effect of Ni-Doping on the Optical, Structural, and Electrochemical Properties of Ag₂₉ Nanoclusters

Atomically precise metal nanoclusters (NCs) can be compositionally controlled at the single-atom level, but understanding structure-property correlations is required for tailoring specific optical properties. Here, the impact of Ni atom doping on the optical, structural, and electrochemical properties of atomically precise 1,3-benzene dithiol (BDT) protected Ag₂₉ NCs is studied. The Ni-doped Ag₂₉ (NiAg₂₈(BDT)₁₂) NCs, are synthesized using a co-reduction method and characterized using electrospray ionization mass spectrometry (ESI MS), ion mobility spectrometry (IMS), and X-ray photoelectron spectroscopy (XPS). Only a single Ni atom doping can be achieved despite changing the precursor concentration. Ni doping in Ag₂₉ NCs exhibits enhanced thermal stability, and electrocatalytic oxygen evolution reaction (OER) compared to the parent NCs. Density functional theory (DFT) calculations predict the geometry and optical properties of the parent and NiAg₂₈(BDT)₁₂ NCs. DFT is also used to study the systematic single-atom doping effect of metals such as Au, Cu, and Pt into Ag₂₉ NCs and suggests that with Ni and Pt, the d atomic orbitals contribute to creating superatomic orbitals, which is not seen with other dopants or the parent cluster. The emission mechanism is dominated by a charge transfer from the ligands into the Ag core cluster regardless of the dopant.