Atomically Precise Ag₄₂ Nanocluster: Shell Structure Modulation and Photothermal Conversion Properties

Understanding the impact of shell structure on the photothermal conversion properties remains a key challenge. Herein, we report the synthesis and characterization of Ag₄₂(SPhF₅)₂₄(P(Ph-m-OMe)₃)₈ (denoted as Ag₄₂) NC, featuring a hollow Ag₁₂ core and an integrated Ag₃₀S₂₄P₈ outer shell. Ag₄₂ exhibits remarkable photothermal performance, achieving a temperature rise of 22.4 °C and a photothermal conversion efficiency (PCE) of 75.27% under 450 nm light irradiation in CHCl₃ (150 mg/L), significantly outperforming the classical [Ag₄₄(SPhF₂)₃₀]^4- (denoted as Ag₄₄) with ΔT = 4.5 °C and PCE = 35.27%, while also maintaining higher stability under prolonged irradiation. This enhanced performance is associated with the shell modulation of Ag₄₂ and its photophysical/structural consequences, including a high molar absorption coefficient (ε = 1.36 × 10⁵ L·mol^-1·cm^-1), favorable metal-to-ligand charge transfer with metal-centered contribution, nearly negligible PLQY (∼0%), and enhanced shell rigidity. These findings provide new insights for designing more efficient photothermal materials.