Strong interaction between plasmon and topological surface state in Bi ₂ Se ₃ /Cu _{2- <i>x</i>} S nanowires for solar-driven photothermal applications

Developing high-performance photothermal materials and unraveling the underlying mechanism are essential for photothermal applications. Here, photothermal performance improved by strong interaction between plasmon and topological surface state (TSS) is demonstrated in Bi₂Se₃/Cu_2-<i>_x</i>S nanowires. This hybrid, which Cu_2-<i>_x</i>S nanosheets were grown on Bi₂Se₃ nanowires, leverages the plasmon resonance and TSS-induced optical property, generating wide and efficient light absorption. A series of tests reveals the strong resonance coupling, TSS-induced hot electron injection, and plasmon-induced hot hole relaxation within the hybrids, endowing the Bi₂Se₃/Cu_2-<i>_x</i>S with excellent photothermal performance. By integrating the hybrids into a hydrogel with a thermoelectric module, the Bi₂Se₃/Cu_2-<i>_x</i>S evaporator achieves a remarkable water evaporation rate of 3.67 kilograms per square meter per hour with a solar-to-vapor efficiency of 95.2%, and a maximum output power of 1.078 watts per square meter under simulated sunlight irradiation. Moreover, a conical mirror was introduced to the device, which greatly enhances the evaporation rate and maximum output power without additional energy input.