Fig. 2.

Photothermal performance (a–d): (a) Temperature changes of TiO₂ nanostructures in air (power = 0.8 W cm⁻²); (b) Temperature changes of the TiO₂ nanostructures in water (power = 0.8 W cm⁻²); (c) Temperature rise and fall of the TiO₂ nanostructures in water when irradiation is turned on/off (power = 0.8 W cm⁻²); (d) Cooling profiles of the TiO₂ nanostructures in PBS after turning off the laser (power = 0.8 W cm⁻²). Detection of ROS upon irradiation with 808 NIR light at 0.8 W cm⁻² for 15 min(e-h): (e1) ¹O₂ and (e2) ⋅OH detected from the decay of DPBF and methyl violet of the TiO₂ nanostructures; (f1-h1) ¹O₂ detected from the decay of DPBF of Ti, NS4 and Na₂Ti₂O₅ nanorod arrays upon irradiation at different time, respectively; (f2-h2) ⋅OH detected from the decay of methyl violet of Ti, NS4 and Na₂Ti₂O₅ nanorod arrays upon irradiation at different time, respectively.