AgI–Ag2S heterostructures for photothermal conversion and solar energy harvesting

Heterostructures are emerging as efficient optical absorbers for photothermal therapy and solar thermal applications because of their excellent photothermal properties. In the current work, AgI–Ag₂S heterostructures with enhanced and broadened optical absorption properties were prepared as photothermal materials. The synthesized AgI–Ag₂S heterostructures are more efficient than the corresponding AgI and Ag₂S nanopartilces and exhibit stronger absorption within the spectrum from 500 nm to 1100 nm. In comparison to the solar spectrum, the aqueous suspension containing 0.03 wt{0b7da518931e2dc7f5435818fa9adcc81ac764ac1dff918ce2cdfc05099e9974} AgI–Ag₂S heterostructures delivers a solar weighted absorption (A_m) value of 97.7{0b7da518931e2dc7f5435818fa9adcc81ac764ac1dff918ce2cdfc05099e9974} at a penetration distance of 1 cm, which means 97.7{0b7da518931e2dc7f5435818fa9adcc81ac764ac1dff918ce2cdfc05099e9974} solar energy has been absorbed. Under the illumination of an 808 nm laser at the power of 420 mW, the photothermal efficiency of the AgI–Ag₂S heterostructures is determined to be 52{0b7da518931e2dc7f5435818fa9adcc81ac764ac1dff918ce2cdfc05099e9974}. For the solar simulation experiment, the solar thermal efficiency of the suspension is evaluated to be 97{0b7da518931e2dc7f5435818fa9adcc81ac764ac1dff918ce2cdfc05099e9974}. The results of the current work provide a solid evident that heterostructures without metal nanoparticles can also have superior photothermal properties than the corresponding single component nanoparticles. It is also evident that AgI–Ag₂S heterostructures have potential applications in photothermal therapy and solar energy harvesting.