Atomically Precise Ag ₄₂ 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 Ag 42 (SPhF 5 ) 24 (P(Ph- m -OMe) 3 ) 8 (denoted as Ag 42 ) NC, featuring a hollow Ag 12 core and an integrated Ag 30 S 24 P 8 outer shell. Ag 42 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 CHCl 3 (150 mg/L), significantly outperforming the classical [Ag 44 (SPhF 2 ) 30 ] 4– (denoted as Ag 44 ) with Δ T = 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 Ag 42 and its photophysical/structural consequences, including a high molar absorption coefficient (ε = 1.36 × 10 5 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.