Plasmonic damping and hot-carrier localization in Al-Pd/Pt nanostars

We investigate the plasmonic response of aluminum nanostars and their Pd- and Pt-functionalized derivatives using an atomistic fluctuating-charge and fluctuating-dipole electrodynamic framework. Full-resolution absorption spectra, near-field maps, induced charge densities, and hot-carrier proxies reveal clear composition-dependent trends. The pure Al nanostar supports a strong LSPR at 2.12 eV, while Pd and Pt decoration redshifts the resonance to 1.88 eV and 1.76 eV and increases damping due to transition-metal interband losses. Near-field and induced-density analyses show that Pd and Pt tips suppress coherent charge oscillations and redistribute hotspots toward the core-tip junctions. Hot-carrier proxies further indicate that transition-metal sites act as localized dissipative sinks. These results establish Al-Pd and Al-Pt nanostars as tunable mixed-metal antennas for UV plasmonics and photocatalysis, and highlight the importance of atomistic electrodynamics in capturing plasmon-interband hybridization in heterometallic nanostructures.