Photothermal Heating and Real‐Time In Situ Luminescent Thermometry with Iron Oxide Core‐Silica Shell Nano‐Objects

Abstract In a world increasingly focused on precision and efficiency, achieving reliable nanoscale thermal feedback in nanoparticle‐assisted heating presents significant challenges. It requires meticulous control over the morphology of nano‐objects and the precise spatial arrangement of the heater and the local temperature probe, both of which are critical for accurate surface temperature readouts. In this work, real‐time nanoscale temperature measurements are presented during the nanoparticle‐assisted photothermal heating by using new nano‐objects consisting of single iron oxide nanoparticles encased in stellate‐like silica shells, loaded with a luminescent coordination compound, namely [(Tb/Eu) ₉ (acac) ₁₆ (μ ₃ ‐OH) ₈ (μ ₄ ‐O)(μ ₄ ‐OH)]. These multifunctional nano‐objects act as efficient light‐triggered nano‐heaters and as ratiometric luminescent thermometers operating between 20–65 °C in water with excellent cyclability and good maximum relative thermal sensitivity of 0.75 ± 0.02% °C ⁻¹ at 65 °C and thermal uncertainty of 1 °C. Real‐time in situ temperature monitoring via the Tb ³⁺ /Eu ³⁺ luminescence intensity ratio during photothermal heating under 808 nm irradiation demonstrates reproducibility and reliable thermal feedback, highlighting its potential for advanced temperature‐responsive applications.