DFT Study of Structural, Chemical, and Optical Properties in Cu_n and PdCu_n-1 Clusters (n = 3-20)

Bimetallic nanoclusters exhibit catalytic activity and electronic properties susceptible to single-atom changes. Previous theoretical studies on Pd-doped copper clusters have focused on narrow size ranges or magic numbers of atoms (e.g., 13, 38, 43, and 55), limiting comprehensive understanding and experimental comparison. We employ a growth-pattern algorithm to explore the potential energy surface of the Cu_n and PdCu_n-1 clusters (n = 3-20), identifying new putative global minima for PdCu₇ and PdCu_9-11. For both systems, we analyze their structural, electronic, chemical, and optical properties as a function of size. Structural analysis shows that progressive Cu addition stabilizes Pd in apical positions, reducing electron acceptance barriers and enhancing nucleophilicity compared to its pure copper counterpart. Concurrently, Cu addition induces a blueshift in UV-Vis absorption spectra, indicating increased electronic transition energies. These findings suggest promising applications for these bimetallic clusters in catalysis and electronic sensing.