Solar steam generation on scalable ultrathin thermoplasmonic TiN nanocavity arrays

Plasmonic-based solar absorbers exhibit complete light absorption in a sub-?m thickness, representing an alternative to mm-thick carbon-based materials most typically employed for solar-driven steam generation. In this work, we present the scalable fabrication of ultrathin plasmonic titanium nitride (TiN) nanocavity arrays that exhibit 90% broadband solar light absorption within - 250 nm from the illuminated surface and show a fast non-linear increase of performance with light intensity. At 14 Suns TiN nanocavities reach - 15 kg h?1 m?2 evaporation rate and - 76% thermal efficiency, a steep increase from - 0.4 kg h-1 m? 2 and - 20% under 1.4 Suns. Electromagnetic, thermal and diffusion modeling of our system reveals the contribution of each material and reactor component to heat dissipation and shows that a quasi-two-dimensional heat dissipation regime significantly accelerates water evaporation. Our approach to ultrathin plasmonic absorbers can boost the performance of devices for evaporation/desalination and holds promise for a broader range of phase separation processes.