• • Au@TiN core-shell nanostructures enable precise LSPR tuning from 550 to 900 nm by varying Au core diameter (20–80 nm) and TiN shell thickness (5–20 nm), as confirmed by single-particle scattering spectroscopy.
• • Photothermal conversion efficiency reaches 78.5% under 808 nm laser irradiation, a 1.74-fold improvement over pure TiN nanoparticles (45.2%), attributed to plasmon hybridization and enhanced absorption.
• • Experimental scattering spectra match finite-difference time-domain (FDTD) simulations with <5% deviation in peak position, validating the plasmon hybridization model for core-shell geometry.
• • The nanostructures exhibit excellent structural stability: no significant spectral shift (<2 nm) after 10 heating-cooling cycles (25–100°C) in aqueous media, indicating robustness for photothermal applications.