Mn5Si3@SiO2 Nanowires as Reusable High-Temperature Photothermal Nanoheaters

Abstract

High-performance photothermal conversion materials are important to light-operated heating, detection, and imaging. Except for the requirement of high efficiency, availability in severe conditions stands as another essential for extensive applications. Herein, with Mn₅Si₃ cores as the heating medium and dielectric SiO₂ shells to optimize energy utilization (promoting light absorption and reducing heat loss), Mn₅Si₃@SiO₂ nanowires output a photothermal conversion efficiency of ∼60.12% that can work stably at a temperature of >460 °C (980 nm laser excitation). Microscopic thermal imaging reveals a well-controllable power-temperature dependence with rapid response (<100 ms). A coil of Mn₅Si₃@SiO₂ nanowires succeeds in igniting sucrose crystals, melting metal tin in an air environment, and achieving a laser-driven large-scale hydrothermal synthesis of self-assembled ZnO nanorods. These experiments confirm the availability of a complex physical and chemical environment for micro- and macroscale photothermal applications.