Kurosch Rezwan

This study presents the synthesis of ceramic open cell foams as a new platform for photothermal energy conversion based on the inert structural ceramic alumina and the plasmonic transition metal nitride TiN. TiO 2 precursor grains inside the mixed ceramic matrix are converted to TiN via the molten salt synthesis route. Photothermal measurements using an 850 nm LED as a light source show that the ceramic foams with only ≈5% TiN in the alumina matrix showed a 34% increased efficiency in converting light to heat compared to flat ceramic discs of the same composition. The TiN content in the flat discs does not affect the heat conversion efficiency, indicating that the available surface area and the material's ability to trap and direct light to the plasmonic nanostructures are the most important parameters for its photothermal activity. These results show the feasibility of synthesizing mixed ceramics based on inert materials like alumina and transition metal nitrides. Applications in solar heating, water evaporation, and related use cases of photothermal energy conversion can be realized with improved performance over 2D materials. Particularly processes that are based on continuous flow like solar thermal heating or photothermal catalysis will benefit from this new material platform.