At present, fabrication methods of selective solar absorbers (SSAs) are costly, involving, vacuum micro-nano processing technology, such as magnetron sputtering and evaporation. To push wider commercialization and larger-scale deployment of SSAs, utilization of economically scalable methods is preferable. This work demonstrates the fabrication of large-area all-ceramic plasmonic SSAs, where both the solar absorbing layer of titanium nitride nanoparticles and polysilazane-derived anti-reflection layer are deposited by ultrasonic spray coating (USC) under ambient conditions. Through careful optimization, the key parameters in fabricating high-performance SSAs by USC are identified: the substrate surface energy, solution concentration, and deposition flow rate. The coatings are optimized...[ Read more ]

At present, fabrication methods of selective solar absorbers (SSAs) are costly, involving, vacuum micro-nano processing technology, such as magnetron sputtering and evaporation. To push wider commercialization and larger-scale deployment of SSAs, utilization of economically scalable methods is preferable. This work demonstrates the fabrication of large-area all-ceramic plasmonic SSAs, where both the solar absorbing layer of titanium nitride nanoparticles and polysilazane-derived anti-reflection layer are deposited by ultrasonic spray coating (USC) under ambient conditions. Through careful optimization, the key parameters in fabricating high-performance SSAs by USC are identified: the substrate surface energy, solution concentration, and deposition flow rate. The coatings are optimized by monitoring their optical spectra and surface morphology. The large-area SSA’s solar absorptance and infrared emittance are 90% and 2%, respectively, resulting in solar-thermal conversion efficiency of 89% on copper substrate. This is a comparable performance to commercially available SSAs, such as black chrome (efficiency of 87%) and cermet-based TiNOX (efficiency of 91%). The laboratory-scale cost of the SSAs on aluminium substrate is down to 4.78 USD/m². USC also has an advantage of wide compatibility with substrates, and this is demonstrated through fabrication of photothermal textile and deicing coating on power lines. Moreover, the application of SSA is showcased in solar desalination. The SSA coating was used to make a flat plate collector, which was then coupled to vacuum membrane distillation. In a closed feed loop design, higher flow rate resulted in higher feed temperature and thus higher permeate flux. The achieved average permeate flux was 29.4 L m^-2 h^-1 under 1 sun, showing great promise in applying solar heat for desalination.