Fig. 2

a FTIR spectra of AIPH, PDA, AP, PVP-CuS and APCZ. b UV–vis–NIR spectra of PVP-CuS, AIPH, AP and APCZ in DI water. c UV–vis–NIR spectra of aqueous APCZ dispersions at different concentrations. d Photothermal curves of aqueous APCZ dispersions at different concentrations exposed to a 1064 nm laser (1.0 W cm⁻², 10 min). e Photothermal curves of aqueous APCZ dispersion (200 µg mL⁻¹) exposed to a 1064 nm laser with different power densities (0.5, 1.0 and 1.5 W cm⁻²) for 10 min. f Photothermal response of aqueous APCZ dispersion (200 µg mL⁻¹) with (first 10 min) and without (next 10 min) exposure to a 1064 nm laser (1.0 W cm⁻²). g Linear fitting for time and − ln θ. h Photothermal response of aqueous APCZ dispersion (200 µg mL⁻¹) for four successive on/off cycles under 1064 nm laser (1 W cm⁻², 10 min) irradiation. i Corresponding infrared thermal images for aqueous APCZ dispersions in d after laser irradiation for 10 min