Enhancement of photo-thermal performance using hole plasmonic nanofluids

A single nanoparticle with broadband and strong optical absorption property has great significance for expanding its utilization and saving cost in various fields. This work utilizes the near-spherical nanocavities distributed on the surface of a single nanoparticles (named as "hole nanoparticles") to optimize the optical absorption performance and to reduce the material cost, especially for plasmonic materials. The cavity effect and the localized surface plasmon resonance effect of the hole plasmonic nanofluids can effectively regulate the absorption band to match the solar spectrum and enhance optical absorption property. Apart from gathering the incident light, the cavity effect can enhance the surface resonance effect, then further enhances the optical absorption. Based on the finite-difference time-domain method, the results show that the photothermal conversion efficiency of silver hole nanofluid and titanium nitride hole nanofluid with a cavity size of 10 nm, a cavity depth of 18 nm, and a cavity number of 49 can separately reach 89.1 % and 91 % at just 10 ppm, among which the silver hole nanofluids have higher photothermal conversion efficiency by 15.4 % than the corresponding solid nanofluids. This work provides an efficient strategy to achieve the broadband-spectrum utilization of the single nanoparticle with the low material usage.